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The shock-to-detonation transition properties of the triaminotrinitrobenzene based PBX 9502 high explosive (HE) are experimentally and computationally explored in extremely high input pressure conditions. These include both slightly sub-Chapman–Jouguet and overdriven input pressure conditions, namely, ∼ 25 and ∼ 31 GPa, respectively. Our experiments capture the transient buildup of a shock-induced reaction via measurement of HE and polymethyl methacrylate window interface particle velocity profiles for a variety of sample thicknesses for this insensitive HE. These observations necessitate extremely thin explosive samples, and the high rates of reaction provide a considerable challenge to optical diagnostics. Samples at these thicknesses also provide an opportunity for evaluation of potential micro-structure effects on the resulting shock-to-detonation-transition measurements. To address this, the thin samples are also characterized via x-ray micro-computed tomography. Finally, a pair of previously established continuum-level detonation performance modeling approaches for PBX 9502 were used to analyze the experiments. The employed model variants crucially differ in their definition of each model's empirical reaction rate functional form, utilization of shock state quantities, and local flow variable dependencies. As a result, the present experiments provide a novel platform to evaluate the quantitative and qualitative consequences stemming from these modeling choices in a challenging initiation scenario, largely beyond the chosen calibration range of either model. This new experimental information will provide a platform for both improved physics and model parameterizations for this well-studied explosive. [ABSTRACT FROM AUTHOR]

The plastic flow of ultra-high molecular weight polyethylene (UHMWPE) at a frictional interface, which is critical to the wear behavior, was investigated by reactive molecular dynamics simulations. The UHMWPE substrate was found to experience various deformations during the friction process. First, some polyethylene (PE) chains could detach from the substrate because of their rapid movement. Second, the frequent motion of PE chains also resulted in the intermittent formation and breaking of cavities between intermolecular PE chains. These deformations were more obvious on a surface with a convex protrusion, where the plowing effect exacerbated the cavitation and elastic deformation of PE chains. Correspondingly, the plastic flow in turn reconstructed the convex protrusion by displacing the surface atoms on the Fe slab. The plastic flow of PE chains broke the C–C bonds, and the carbon moieties were then chemically bonded onto the metal surface. A rapid change of atomic charge, hence, happened when the bonds broke. Meanwhile, PE chains release short alkyl radicals gradually after bond breakage, indicating gradual wear of the substrate during friction. This work provides molecular insight into the evolution of interfacial microstructure under plastic flow on a UHMWPE substrate. [ABSTRACT FROM AUTHOR]

K‐feldspar, which constitutes about 60%$\%$ of the Earth's crust, is crucial for understanding electrical conductivity in porous rocks. Its electrical properties are vital for applications in ceramics, electrical insulation and conductive polymers. In this work, we study the time evolution of electrical conductivity of K‐feldspar‐rich rocks with varying temperatures, at high and low pH, which has been studied through simulation using time domain random walk. Random walkers, mimicking ions in transport, move in accordance with appropriate hydrodynamic equations, dissolution and precipitation kinetics. Electrical conductivity has been calculated considering variations in the parameters of temperature, fluid pH and the abundance of K‐feldspar in rocks. Electrical conductivity is found to increase with temperature up to a critical value, after which it decreases. The sharpness of the rise and fall in electrical conductivity is quantified through a measure defined as the conductivity quality factor Qσ$Q_{\sigma }$. We find that Qσ$Q_{\sigma }$ increases with a decrease in the availability of K‐feldspar mineral. Our simulated results of electrical conductivity show a good match with the experimental trends reported. [ABSTRACT FROM AUTHOR]

The chemistry mechanism has great significance in the simulations of supersonic combustion flow. A pre-partitioned adaptive chemistry with pre-exponent adjustment (PPAC-PEA) method has been proposed to develop an efficient and accurate reaction mechanism for simulating supersonic hydrogen combustion. The main idea is to adjust the pre-exponents of reactions based on the local gas state, minimizing the error in ignition delay time between a simplified mechanism and a detailed one. The PPAC-PEA method reproduced the detailed mechanism's ignition delay time with errors less than 0.08 orders of magnitude across a wide range of 900–1800 K temperatures and 0.5–10 atm pressures. Importantly, the PPAC-PEA mechanism achieves significant computational speedups of 3.77 to 5.91 times in several cases while maintaining excellent accuracy. In the case of the 2D oblique detonation, the PPAC-PEA mechanism shows only a 2.2% deviation in detonation wave position. These promising results demonstrate the PPAC-PEA method as an attractive solution for efficient and accurate numerical simulations of supersonic reactive flows. [Display omitted] • A PPAC-PEA method for efficient and accurate supersonic combustion simulations. • The magnitude of average ignition delay time error decreases from above 0.31 to below 0.08. • 2.2% deviation in the detonation wave position for a 2D oblique detonation simulation. • The optimized mechanism achieves speedups of 3.77 to 5.91 times compared to the detailed mechanism. [ABSTRACT FROM AUTHOR]

Recent studies of the Cretaceous lower arc crust exposed in Fiordland, New Zealand, conclude that shear zones are sites of melt migration and mass transfer through the deep crust. Here, we investigate the 4–10 km‐wide George Sound Shear Zone, which cuts the Western Fiordland Orthogneiss, comprising two main rock types: two‐pyroxene gneiss and hornblende gneiss. Previous studies infer a predominantly igneous origin for the two types of gneiss. However, this study finds that melt‐rock interaction within the George Sound Shear Zone formed the hornblende gneiss from the precursor two‐pyroxene gneiss. Petrographic analyses of samples collected in transects across the shear zone show hydration reaction textures ranging from rims of hornblende + quartz around pyroxene grains to complete replacement of pyroxene grains. Plagioclase is recrystallized and partially replaced by clinozoisite. Additionally, biotite mode increases towards the higher strain rocks in the shear zone. Backscatter images and polarized light microscopy show microstructures indicative of former melt‐present deformation, including (a) interconnected mineral films of quartz and K‐feldspar along grain boundaries, (b) grains that terminate with low apparent dihedral angles, (c) interstitial grains, with some (d) undulose extinction in plagioclase and (e) serrated grain boundaries. In addition, zircon microstructures are consistent with Zr mobility, further supporting the former presence of melt; geochemical data show enrichment of Zr in the hornblende gneiss as compared to the two‐pyroxene gneiss. From the above observations, it is inferred that a felsic to intermediate hydrous melt migrated through the George Sound Shear Zone reacting with the host two‐pyroxene gneiss of the Western Fiordland Orthogneiss. Melt migration along grain boundaries was deformation assisted, (i) causing hydration of pyroxene to hornblende + quartz, and plagioclase to clinozoisite, (ii) increasing proportions of biotite within the shear zone and (iii) causing depletion of Cr + Ni and Zr enrichment in the hydrated rock. Our interpretation is supported by published observations of pegmatite dyke swarms that intruded into the George Sound Shear Zone, the P‐T conditions of deformation and characterization of microstructures that contrast sharply with those typically found in mylonitic rocks formed under solid‐state metamorphic conditions. Our results confirm that hydrous shear zones within otherwise anhydrous country rock are retrogressive and may represent evidence of melt migration through zones of deformation. [ABSTRACT FROM AUTHOR]

Bioconvection in hybrid nanofluids refers to the phenomenon where biological microorganisms such as algae or bacteria exhibit collective movement or pattern formation in a suspension containing nanoparticles. This phenomenon has significance in various fields, including biology, nanotechnology, and engineering. The current investigation emphasizes the bioconvective flow of a water (H2O)−ethylene glycol (C2H6O2)-based hybrid nanofluid flow by a curved stretched sheet. Copper (Cu) and silver (Ag) nanoparticles are suspended in the base fluid. The thermal field is analyzed in the presence of heat generation, dissipation, Joule heating, and the impact of thermal radiation. Binary reactions associated with Arrhenius energy are accounted in the modeling of mass concentration. The phenomenon of bioconvection is considered to regulate the random movement of tiny solid particles within the flow. Boundary layer constraints are implemented to eliminate ineffective terms from modeling. The transformation procedure is adopted to obtain the flow governing system of ODEs. The built-in code of Mathematica (NDSolve) is implemented to obtain the graphical and numerical results. The results show that the velocity field decreases with increasing porosity variable and Hartmann number. An opposite impression of the Eckert number and Schmidt variable on the thermal field is noticed. Bioconvection Peclet and Lewis numbers have a direct relationship with motile density. [ABSTRACT FROM AUTHOR]

Road lighting is one of the most important services provided by public entities. Entities providing such a service are interested in providing it with the lowest possible financial outlays. When planning modernization, unfortunately, one forgets about hidden operating costs, which are caused by, among others, the flow of reactive energy in the circuit. The use of modern light sources also involves the use of electronic systems in their accessories, which makes these electrical energy receivers capacitive. This is due to the lack of use of individual compensation systems in the luminaires themselves. Due to the above, the costs of capacitive reactive energy flow also increase. Newly designed road lighting installations, as well as modernized ones, are equipped with electronic systems enabling their effective control. The operation of such systems also causes fluctuations in the reactive power value, which must be compensated. Commonly used compensation choke systems also introduce additional active power losses, which makes the expected savings lower than expected. In the article, the authors presented selected results of measurements of the electrical parameters of LED luminaires, carried out both in the laboratory and in used road lighting circuits. The determined amounts of active power losses caused by the installation and operation of additional equipment in the road lighting installation, such as compensating chokes, are presented. The calculations were made based on the example of a selected fragment of the audit of this installation. On this basis, modernization was carried out and measurements of current electricity quality parameters were carried out. [ABSTRACT FROM AUTHOR]

Recycling production waste in the reactive injection molding (RIM) process is a step towards sustainability and efficient material usage. The recycled thermoset composite (RTC) material obtained by shredding the production waste is reused with a virgin thermoset composite (VTC). This study presents a mold-filling simulation approach considering this polydisperse suspension of RTC and VTC. Mold-filling simulations can assist in predicting processability and assessing the impact of reinforced RTC on the final part of production. State-of-the-art mold-filling simulations use the Cross–Castro–Macosko (CCM) model or anisotropic fiber-orientation-dependent viscosity models. The rheological parameters are determined either for the VTC or neat resin. However, these models do not account for changes in viscosity due to the reinforcing of fillers such as RTC. An effective viscosity model is developed by extending the CCM model using the stress–strain amplification approach to overcome this gap. This model is implemented in the computational fluid dynamics code OpenFOAM, and simulations are performed using an extended multiphase solver. To validate the simulations, experimental trials were executed using a two-cavity mold equipped with pressure sensors. Molding compounds with different compositions of VTC and RTC were injected at different speeds. Reinforcing VTC with RTC increases the viscosity. Results demonstrate that RTC-reinforced compounds require higher injection pressure for mold filling than VTC alone. The qualitative agreement of pressure profiles from simulations and experiments for different proportions of reinforcing RTC and different injection speeds shows that the implemented viscosity model can reproduce the experimental mold-filling behavior. [ABSTRACT FROM AUTHOR]

The power factor (PF) plays a crucial role in determining the quality of energy produced by grid-connected photovoltaic (PV) systems. When irradiation levels are high, typically during peak sunlight hours, the PV panels generate more electricity. In this scenario, the PF tends to be higher because the real power output closely matches the apparent power drawn from the grid. Whereas, when irradiation levels are low, such as during cloudy weather or nighttime, the PV panels produce less electricity. In these conditions, the power factor may decrease because the real power output diminishes compared to the apparent power drawn from the grid. This could be due to reduced efficiency or increased reactive power flow. PF decreases linearly at solar irradiance values lower than 220 (W/m2). At the same time, it approaches unity at higher solar irradiance values than 220 (W/m2). In this study, the variation of the power coefficient of the grid-connected PV solar system depending on solar irradiation was modeled and analyzed using MATLAB/Simulink 41016490. The analytical expression of the power factor depending on the change in solar irradiation was found using the curve fitting method. [ABSTRACT FROM AUTHOR]

Experimental and numerical simulation of launcher base flows are crucial for future launcher design. In experiments, exhaust plume simulation is often limited to cold or slightly heated gases. In numerical simulations, multi-species reactive flow is often neglected due to limited resources. The impact of these simplifications on the relevant flow features, compared to real flight scenarios, needs to be characterized in order to enhance the design process. Experimental and numerical investigations were carried out within the framework of the SFB/TRR 40 Collaborative Research Centre to study the impact of plume and wall temperature on the base flow of a generic small-scale launcher configuration. Wind tunnel tests were performed in the Hot Plume Testing Facility (HPTF) at DLR, Cologne, using subsonic ambient flow and pressurized air or hydrogen–oxygen combustion as exhaust gases. The tests were numerically rebuilt using the DLR TAU code employing a scale-resolved IDDES approach, including thermal coupling and detailed chemistry. The paper combines the experimental and numerical findings from the SFB/TRR 40 base flow studies and highlights the most prominent influences on the mean flow field, the pressure field, the dynamic wake flow motion, and the resulting aerodynamic forces on the nozzle. High-frequency pressure measurements, high-speed schlieren recordings, and time-resolved CFD results are evaluated using spectral and modal analysis of the one- and two-dimensional flow field data. [ABSTRACT FROM AUTHOR]

The present study introduces a rapid and accurate customized solver on the OpenFOAM platform for large-scale industrial computations. Specifically, a sparse analytical Jacobian approach utilizing the SpeedCHEM library was implemented to enhance the efficiency of the ordinary differential equation solver. The dynamic load balancing code was used to distribute computational workloads uniformly across multiple processes. Optimization continued with open multi-processing to improve parallel computing efficiency and the local time stepping scheme to maximize individual cell time steps. The effectiveness and robustness of the customized solver were first validated using Sandia flames D–F as benchmarks. The results showed that the customized solver exhibited better strong scaling characteristics and led to a speed increase of up to 30 times for two-dimensional Sandia flame D calculations. The numerical predictions for temperature and species distribution closely matched the experimental trends, confirming the accuracy of the solver. Subsequently, a three-dimensional numerical study on a 10 kW ammonia co-combustion furnace was conducted, exploring the performance of the solver in large-scale reactive simulations. Results analysis indicated that the acceleration capability was reduced due to increased communication overhead between processors, achieving up to 7.06 times speed-up. However, as the size of the reaction mechanism increases, better acceleration capabilities can be demonstrated. The numerical predictions could closely replicate experimental trends, effectively predicting NO emission trends within the combustion furnace. This study offers one viable solution for rapid and accurate calculations in the OpenFOAM platform, which could be applied in the subsequent ammonia industrial combustion processes. [ABSTRACT FROM AUTHOR]

Due to the complexity and short timescale of detonation, it is usually difficult to capture its transient characteristics experimentally. Advanced numerical methods are essential for enhancing the understanding of the flow field structure and combustion mechanism of detonation. In this study, a density-based compressible reactive flow solver called CDSFoam is developed for simulating gas-droplet two-phase detonation combustion based on OpenFOAM. The primary feature of this solver is its implementation of two-way coupling between gas and liquid phases, utilizing the Eulerian–Lagrangian method. The key enhancement is an improved approximate Riemann solver used to solve the convective flux, reducing dissipation while ensuring robustness. Time integration is achieved through the third-order strong stability preserving Runge–Kutta method. Additionally, CDSFoam incorporates dynamic load balancing and adaptive mesh refinement techniques to mitigate computational costs while achieving high-resolution flow fields dynamically. To validate the reliability and accuracy of the solver, a series of benchmark cases are examined, including the multi-component inert and reactive shock tube, the stable diffusion process, the Riemann problem, the one-dimensional detonation, the two-dimensional detonation and oblique detonation, the droplet phase model, the two-dimensional gas–liquid two-phase detonation, and the two-phase rotating detonation. The results show that CDSFoam can well predict the shock wave discontinuity, shock wave induced ignition, molecular diffusion, detonation key parameters, detonation cell size, and the main characteristics of gas–liquid two-phase detonation. [ABSTRACT FROM AUTHOR]

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A novel technique is presented to improve the initialization of compressible combustion LES, DNS or URANS by numerically turning the flame into a damper to quickly remove (artificial) pressure fluctuations and acoustic energy from the system. This is achieved by modifying the pressure dependency of the heat release rate, effectively modifying the Rayleigh Integral to achieve negative values, so that the acoustic energy is quickly removed from the system. The technique can (a) reduce the cost of simulations (by shortening the initialization), (b) contribute to stabilize the simulation, (c) help to avoid unrealistic thermoacoustic modes and, (d) potentially, be modified to compensate for excessive numerical dissipation of acoustic energy. Examples from LES of a thermoacoustic test case are presented to demonstrate the effective stabilization achieved. [ABSTRACT FROM AUTHOR]

Flow behavior of nonlinear materials over magnetized and contracting and extending inclined surfaces is described specifically by Jeffery–Hamel type flow, where the flow is caused by a convergent/divergent channel with the appearance of a source or sink. The role of the conversion of more than one species to more than every other species is significant in the flow conduct of such types of nonlinear materials. However, for the desired higher thermal conductivity, the Brownian motion and thermophoretic forces are incorporated in this particular work. Moreover, the impacts of first‐order chemical reaction and slips on the velocity, thermal, and concentration distributions, respectively presented to portray the importance of the entire study. The liquid motion on such surfaces is further addressed with the involvement of viscous dissipation and solar radiation. The newly mathematically formulated work is then approximated via one of the built‐in approaches based on collocation methods. The key findings are determined through graphical illustration. The physically interesting growing velocity of the liquid motion is noticed with variation in the slippery motion parameter during the convergent channel case. The opposite trend is noted for the divergent channel case. Furthermore, the Brownian motion‐related parameter escalated the temperature of the liquid, and the reverse status of the liquid concentration is determined with variation in the same parameter. The mass fraction is determined in a declining conduct with the ascending variation in first‐order chemical reaction factor. At the end of the work, a comparison with existing results is provided with excellent agreement. [ABSTRACT FROM AUTHOR]

The structure of the lithosphere and the associated magmatic systems found in different locations along slow‐spreading ridges can vary dramatically, from melt‐starved to magmatically robust segments. A growing number of studies suggest that the evolution of the magmatic crust being governed solely by fractional crystallization is too simplistic. Reactions between migrating melts and their surroundings play a key role during accretion, yet the full extent of their impact is still to be resolved. We present here the results of a petrological, microstructural, and in situ geochemical study of two drilled sequences from the Kane Megamullion and Atlantis Massif oceanic core complexes. We show that melt‐mush reactions generate locally strong textural and/or geochemical heterogeneity at the cm‐scale, but their impact can also be identified at the 100 m‐scale. We found evidence for assimilation at various degrees of primitive lithologies of potential mantle origin within the gabbroic sequence at both locations, in addition to typical melt‐mush reactions previously described in other slow‐spread magmatic systems. Observations and numerical modeling confirm the similarity of the reactions impacting both sequences. However, the regime of the reactions (ranges of assimilation to crystallization ratios) seems to vary between Kane Megamullion and Atlantis Massif, variations which likely result from differences in melt fractions present during melt‐mush reactions. We infer relying on our observations and previous studies that the regime of the reactions is most likely controlled by the melt flux during the formation of the two sections. Key Points: Kane Megamullion and Atlantis Massif oceanic core complexes record widespread melt‐mush reactions at different scalesIn addition to typical melt‐mush reactions, assimilation of primitive (mantle?) lithologies is observed within gabbro sequencesDiscrepancies in the melt‐mush reaction signatures of the two sequences reveal variable melt dynamics during accretion [ABSTRACT FROM AUTHOR]

The article presents a solution to a complex problem involving a transient MHD‐free convective chemically reactive flow. The flow involves a viscous incompressible electrically conducting non‐Gray optically thick fluid moving past a semi‐infinite vertical plate that has suddenly started but is temporarily accelerated. The plate has nonlinear parabolic ramped conditions, and the flow is exposed to thermal radiation, heat absorbing sink, and diffusion‐thermo effect. For the current study, the model fluid being used is moist air. The governing equations are obtained using the Laplace transform technique with the help of the Heaviside step function. This study is the first to consider parabolic ramped motion, temperature and concentration simultaneously. Effects of the pertinent parameters on the Sherwood number and Nusselt number are visualized using 3D surface plotting. Findings of the problem manifest that concentration, temperature, and velocity profiles in case of ramped conditions are less than in isothermal conditions. The rate of heat transfer of mercury is less than oxygen, air, water, and ethanol at a room temperature of 22°C–25°C. The ramped plate has the tendency to augment the heat transfer rate. The present study is of great interest in numerous fields of industry and machine‐building applications. [ABSTRACT FROM AUTHOR]

The influence of bioturbation induced by bottom‐dwelling macrozoobenthos on nitrogen dynamics in lotic stream sediments remains unclear. In this work, we advance the understanding of faunal bioturbation in lotic environments by developing a fully‐coupled flow and multicomponent reactive transport model and investigate the influence of sediment reworking and burrow ventilation processes on nitrogenous transformations. The model results indicate that sediment reworking and burrow ventilation significantly increase nitrate (NO3−) influx, penetration depth, and reaction rates in the streambed. Denitrification rates were observed up to three times higher in beds with U‐shaped burrows compared to flatbeds. The ratio of mound height to stream water depth ratio (h/H0) is a dominant control on determining the relative importance of the sediment reworking and burrow ventilation processes in modulating nitrogenous reactions. A power‐law scaling framework is ultimately proposed to predict NO3− removal efficiency based on the Damköhler number in bioturbated lotic streambeds. Plain Language Summary: The increase in nitrate (NO3−) levels can harm rivers by causing problems like eutrophication, toxic algal blooms, and low oxygen levels. Microbes, like those involved in denitrification, can help reduce NO3− levels in the riverbed, where surface water and groundwater mix. Creatures like macroinvertebrates that live in the riverbed also play a role in how NO3− moves and is used. We wanted to know if these creatures, by disturbing the sediment and irrigating it, change how NO3− behaves in the riverbed. Our computer modeling showed that having U‐shaped burrows in the sediment can enhance the rate at which NO3− is removed, up to three times more than in flatbed sediments. As the ratio of the mound height to the total depth becomes less than 0.1, the influence of sediment reworking on NO3− influx and consumption rates decreases, and burrow ventilation becomes more important. We also came up with a way to predict NO3− removal efficiency in bioturbated riverbeds under flowing water conditions. These findings underscore the significance of bioturbation in rivers with moving water and have important implications for managing and restoring rivers. Key Points: Developing a Navier‐Stokes‐Brinkman‐Darcy‐Reaction fully‐coupled approach to study interplay between nitrogen cycling and faunal bioturbationSediment reworking and burrow ventilation processes could significantly alter the nitrogenous transformations in low flow environmentsA power‐law scaling framework can be used to predict nitrate removal efficiency within the bioturbated sediments from the Damköhler number [ABSTRACT FROM AUTHOR]

Medium-voltage (MV) distribution networks that are spread through larger territory and threatened by extreme weather conditions are sometimes formed by very long underground cable lines. In such circumstances, a significant amount of capacitive reactive power flow can be generated. If, concurrently, there is low power demand in the network, it can result in significant reverse reactive power flows and voltage rise issues. This paper proposes a general approach for analyzing and mitigating voltage rise issues and demonstrates it using an example of a real distribution network that operates under the described conditions. Previous studies that dealt with this problem did not include the allocation of multiple shunt reactors in a larger distribution network, modeling a high number of lines that create reverse reactive power flows, and modeling the main distribution transformers, which are the locations where voltage rise predominantly occurs. In this paper, we demonstrate that precise allocation and placement of multiple shunt reactors in a fully modeled, larger distribution system, including transformer models, can reduce reverse reactive power flows, thereby improving voltage in the distribution system. If hourly control of the power factor from the distributed generation unit is also implemented, the voltage can be further improved. [ABSTRACT FROM AUTHOR]

Geological carbon sequestration in jointed reservoirs will require the use of fracture network for the flow of CO2 plumes. However, acidic solution formed at the interface between brine and CO2 can cause chemical erosion of the local rock mass, especially in rocks with high carbonate content. The use of the water alternating gas technique for injection stimulation can exacerbate this issue, as the water–CO2 interface occurs in areas near the injection point. As a result, acidic flow can impact the surrounding rock mass, particularly around the main flow paths where fracture network conductivity is much higher than matrix permeability. To investigate the impact of acidic flow on fracture conductivity, we conducted an experiment on a fractured sandstone sample that was exposed to CO2-saturated water. Our findings revealed a nearly ten-fold increase in post-experimental water-relative permeability, and restriction of flow within established flow channels, which consist one third of the fracture surface. In conclusion, our study sheds light on the dynamic behavior of fractured sandstone under the influence of CO2–H2O flow, revealing significant changes in transmissivity and fracture geometry. These findings contribute to a better understanding of the hydraulic performance of fractures in the context of geological carbon sequestration. [ABSTRACT FROM AUTHOR]

Reservoir modeling consists of two key components: the reproduction of the historical performance and the prediction of the future reservoir performance. Industry-standard reservoir simulators must run fast on enormous and possibly unstructured grids while yet guaranteeing a reasonable representation of physical and chemical processes. However, computational demands limit simulators in capturing involved physical and geochemical mechanisms, especially when chemical reactions interfere with reservoir flow. This paper presents a mathematical workflow, implemented in IORSim, that makes it possible to add geochemical calculations to porous media flow simulators without access to the source code of the original host simulator. An industry-standard reservoir simulator calculates velocity fields of the fluid phases (e.g., water, oil, and gas), while IORSim calculates the transport and reaction of geochemical components. Depending on the simulation mode, the geochemical solver estimates updated relative and/or capillary pressure curves to modify the global fluid flow. As one of the key innovations of the coupling mechanism, IORSim uses a sorting algorithm to permute the grid cells along flow directions. Instead of solving an over-dimensionalized global matrix calling a Newton–Raphson solver, the geochemical software tool treats the species balance as a set of local nonlinear problems. Moreover, IORSim applies basis swapping and splay tree techniques to accelerate geochemical computations in complex full-field reservoir models. The presented work introduces the mathematical IORSim concept, verifies the chemical species advection, and demonstrates the IORSim computation efficiency. After validating the geochemical solver against reference software, IORSim is used to investigate the impact of seawater injection on the NCS Ekofisk reservoir chemistry. Article Highlights: The IORSim sorting algorithm decouples the nonlinear geochemical reaction calculations into recurring one-dimensional problems to assure numerical stability and computation efficiency. To the best of our knowledge, this work presents the mathematical concept, implementation, and application of topological sorting for the first time on (industry) field-scale problems. IORSim combines topological sorting with basis swapping and splay trees to significantly reduce computation times. Moreover, a high-speed forward simulation mode was developed to allow the post-advection of chemical components to visualize species distribution, water chemistry, and mineral interactions. If the geochemical reactions interfere with the fluid flow, the IORSim backward mode uses relative permeability curves to update the global fluid flow at each time step. We validate the implemented topological scheme on a reservoir grid, show the computation efficiency, and compare the impact of explicit, implicit, and grid refinement on numerical dispersion. The decoupled flow simulator and geochemical reaction calculations allow seamless integration of full-field reservoir models that contain complex geological structures, a large number of wells, and long production histories. The computation capabilities of IORSim are demonstrated by simulating and reproducing the impact of seawater injection in the southern segment of the giant Ekofisk field (more than 50 years of injection and production history). IORSim shows that seawater injection changed the Ekofisk mineralogy and impacted the produced water chemistry. In the investigated Ekofisk case, seawater promoted calcite dissolution and led to the precipitation of magnesite and anhydrite. Moreover, surface complexation modeling revealed that sulfate is adsorbed on the calcite surface. [ABSTRACT FROM AUTHOR]

To overcome the major challenge of reactive flow simulation for chemical kinetics dominated flame dynamics in supersonic combustion, on-the-fly mechanism reduction for high fidelity simulation of scramjet becomes mandatory. For dynamic adaptive chemistry (DAC) methodology, there are three major factors controlling the accuracy and efficiency of the overall simulation, namely, the mechanism reduction method, error threshold value $${\varepsilon _{DAC}}$$ ε DAC , and search initiating species (SIS). In the present work, systematic investigations of the three influential factors were conducted for large eddy simulation of ethylene-fueled supersonic combustion within a unified DAC framework. The results show that all the four mechanism reduction methods, i.e., DRG, DRGEP, PFA, and DAC-L, are adequate for the combustor's global performance prediction regarding the wall pressure, stable combustion productions, and temperature. However, for intricate flame stabilization characteristics, the DRG, DRGEP, and DAC-L methods yield comparable prediction accuracy in radical distributions, whereas the PFA method leads to relatively large discrepancies compared to direct integration with the detailed mechanism. The DRGEP method obtains the best balance between numerical accuracy and computational efficiency among the four methods, while the PFA method is the most computationally demanding one. Regarding the mechanism reduction error threshold value, the relative errors in physical property predictions increase as the relaxation of the error threshold value. And the comparative study suggests that the $${\varepsilon _{DAC}}$$ ε DAC should not exceed $${10^{- 4}}$$ 10 − 4 for high fidelity simulations of supersonic combustion. Furthermore, the stable species combination, namely, fuel, O2, and N2 incurs larger relative errors in radical mass fraction prediction than the combination including fuel and intermediate species HO2 and CO. Nevertheless, the latter is less computationally efficient than the former as it requires 15% more CPU time to solve the stiff ODE system of the resultant skeletal mechanism. It should be noted that the computational overheads for mechanism reduction under various $${\varepsilon _{DAC}}$$ ε DAC values and SIS combinations are almost the same, and the overall computational efficiency is mainly determined by the CPU time for solving the stiff ODE system of the size-reduced skeletal mechanisms. [ABSTRACT FROM AUTHOR]

Calculating the composition of the combustion products serves as the starting point for the high-area ratio (HAR) rocket nozzle. The HAR rocket nozzle finds application in next-generation hypersonic vehicles and missiles. The gas dynamics, gas radiation, and turbulence-chemistry interactions (TCI) play a crucial role in simulations of hypersonic turbulent reactive flows through a rocket nozzle. The interaction of turbulence and chemistry leads to random species mixing and enhanced heat transfer. The k-omega shear stress transport (SST) model is employed to calculate the average flow fields. The eddy dissipation concept (EDC) with reduced chemistry is applied to capture the TCI in the nozzle. The spectral properties of H 2 O are calculated using the full spectrum k -distribution (FSK) model in conjunction with the first-order spherical harmonics method. The mass fractions of combustion products obtained from Particle Swarm Optimization (PSO) and Monte Carlo (MC) methods agree well with the Chemical Equilibrium with Applications (CEA) code. The flow fields obtained with the current solver are validated with the published experimental data. A significant rise and fall of 7–8% have been observed in the centerline flow properties when not including the TCI models in the flow solver. The centerline flow fields obtained with different discretization schemes are in good agreement. The radiative heat flux from the H 2 O species is more dominant than the convective. • Calculate the chemical equilibrium composition of product species for the H 2 –O 2 combustion using the Monte Carlo and PSO methods. • Modeling of the hypersonic turbulent reacting flow of a high-area-ratio (HAR) rocket nozzle in OpenFOAM. • Developed and implemented a spectral model to calculate the radiative properties of H 2 O gas in OpenFOAM. • Effects of turbulence-chemistry interactions (TCI) on the flow fields are analyzed. • Radiative and convective heat transfers are more significant near the throat area. [ABSTRACT FROM AUTHOR]

A non-isothermal physicochemical model of reactive sputtering is extended in this work. The new version is used in this work to simulate reactive sputtering of a sandwich target with two plates of different metals located on the same axis. The external plate contains cut-outs through which the internal plate is sputtered. The main independent process parameters are the reactive gas flow introduced into the vacuum chamber, the discharge current density, and the total area of cut-outs in the external plate. The physical model of the process is described by a system containing 14 algebraic equations. Only its numerical solution is possible, which allows studying the sputtering process in detail. The model can be used to estimate the conditions that ensure the deposition of a compound film in a real technological process. The model was used to analyze sputtering of a target with internal titanium and external tantalum plates in oxygen. Application of the model in particular cases of sputtering of single targets showed that it is adequate. [ABSTRACT FROM AUTHOR]

State estimation stands as one of the most crucial applications in energy management systems of control centres, ensuring the secure operation of the power system. The real‐time availability of accurate system variables, including voltages, currents, and power flows, presents an excellent opportunity to consider the actual network characteristics, including imbalances. This paper presents a linear and non‐iterative method to solve the three‐phase state estimation problem in transmission systems with unbalanced loading. The method utilises supervisory control and data acquisition measurements obtained from remote terminal units. The formulation is based on complex variables derived from traditional supervisory control and data acquisition measurements, with assumptions made regarding the availability of certain three‐phase bus voltages, as well as a number of three‐phase currents and active and reactive power flows. The proposed algorithm employs the classical weighted least squares technique for solving the three‐phase state estimation problem. Due to its straightforward and linear nature, the method ensures no convergence issues. To validate its effectiveness, the proposed method is validated on a three‐bus network and the IEEE 39‐bus network simulated using the three‐phase model within the DIgSILENT Power Factory environment. [ABSTRACT FROM AUTHOR]

The single-phase dual active bridge (DAB) DC/DC converter is a vital component in modern power electronics systems, facilitating efficient bidirectional power transfer between various energy sources and loads. One of the critical aspects in the design of such converters is the selection of an appropriate leakage inductance, as it significantly affects the circulating power within the converter. This study investigates the influence of inductance on the reactive power flow and introduces an analytical formula for calculating the necessary leakage inductance based on the specified rated power of the DAB converter. By employing the inductance values determined through the proposed formula, the developed power control-based modulation method, implemented in discrete time, successfully achieves zero reactive power caused by the first harmonic components under all load conditions. This selection of leakage inductance optimizes the performance of the converter ensuring efficient power delivery across various applications. The applicability of this method extends to various DAB applications, including electric vehicles, integration with asynchronous microgrids, and aerospace systems. [ABSTRACT FROM AUTHOR]

In recent years, the atmospheric pressure plasma jet (APPJ) has gained considerable attention in the field of optical fabrication because the chemical etching approach offers the advantage of avoiding mechanical damage to workpieces. This paper presents the development of an atmospheric pressure plasma machining system with a ring-ring typed APPJ, which exhibits several favorable characteristics. It has a relatively low processing temperature, no electrode corrosion, no plasma contamination, and a long discharge plume, etc. Optimization of the dimensional parameters and analysis of reactive gas flow rate are conducted through experimental investigations. Comparative experiments are carried out with the commonly used needle-ring typed APPJ, revealing significant improvements of the ring-ring typed APPJ, i.e., a fourfold increase in machining distance, a tenfold increase in machining efficiency, and a 58% enhancement in the stability of the material volumetric removal rate. Furthermore, on-line temperature monitoring of the footprint has been achieved due to the specific traits of the extended discharge plume. Fabrication experiments are conducted to demonstrate the significant correlation between the temperature and material removal rate, which shows the possibility of improving the accuracy of optical fabrication based on the ring-ring typed APPJ. • A ring-ring typed atmospheric pressure plasma jet (APPJ) is proposed for optical fabrication, which has a relatively low processing temperature, no electrode corrosion, no plasma contamination, and a long discharge plume. • Optimization of the dimensional parameters and analysis of reactive gas flow rate are conducted through simulations and experimental investigations. • Comparative experiments are carried out with the commonly used needle-ring typed APPJ, revealing significant improvements of the ring-ring typed APPJ, i.e., a fourfold increase in machining distance, a tenfold increase in machining efficiency, and a 58 % enhancement in the stability of the material volumetric removal rate. • On-line temperature monitoring of the footprint has been achieved and the significant correlation between the temperature and material removal rate has been demonstrated. • Fabrication of continuous phase plate is conducted to validate the capability of the ring-ring typed APPJ in machining the sophisticated surface. [ABSTRACT FROM AUTHOR]

A novel volume of fluid method is presented for mineral precipitation coupled with fluid flow and reactive transport. The approach describes the fluid-solid interface as a smooth transitional region, which is designed to provide the same precipitation rate and viscous drag force as a sharp interface. Specifically, the governing equation of mineral precipitation is discretized by an upwind scheme, and a rigorous effective viscosity model is derived around the interface. The model is validated against analytical solutions for mineral precipitation in channel and ring-shaped structures. It also compares well with interface tracking simulations of advection-diffusion-reaction problems. The methodology is finally employed to model mineral precipitation in fracture networks, which is challenging due to the low porosity and complex geometry. Compared to other approaches, the proposed model has a concise algorithm and contains no free parameters. In the modeling, only the pore space requires meshing, which improves the computational efficiency especially for low-porosity media. [ABSTRACT FROM AUTHOR]

This paper presents and discusses the results obtained by the participants to the benchmark described in de Hoop et al, Comput. Geosci. (2024). The benchmark uses a model for CO2 geological storage and focuses on the coupling between two-phase flow and geochemistry. Several test cases of various levels of difficulty are proposed, both in one and two spatial dimensions. Six teams participated in the benchmark, each with their own simulation code, though not all teams attempted all the cases. The codes used by the participants are described, and the results obtained on the various test cases are compared, as well as the performance of the codes. It is shown that the results obtained are widely consistent, giving a good level of confidence in the outcome of the benchmark. The general complexity of two-phase flow coupled with chemical reactions altering porous media means that some differences between the codes remain. Besides, from the convergence study, it is clear that the two-dimensional problem has a relatively high sensitivity to a spatial resolution which adds to the complexity. [ABSTRACT FROM AUTHOR]

Various crustal processes shape both the lower oceanic crust and mid-ocean ridge basalts (MORBs). To better understand how these crustal processes influence MORB compositions, we conducted comprehensive petrographic and geochemical investigations on gabbroic rocks and erupted lavas dredged from a segment of the Central Indian Ridge (CIR) spanning from 7°50′S to 8°30′S. The petrographic and geochemical analyses of the gabbroic rocks revealed evidence of melt-rock reaction through reactive porous flow in olivine gabbro and gabbro. This process resulted in distinctive features in clinopyroxene, including disequilibrium textures with a troctolite/anorthosite matrix, complex variations in Mg#-Cr-Ti [Mg# = molar Mg/(Mg + Fe2+)] relationships, and considerable enrichment and fractionation of incompatible trace elements. A significant finding of our study is the close resemblance of trace element ratios in MORB and olivine-hosted melt inclusions to those of melts in equilibrium with clinopyroxene from olivine gabbro and gabbro with Sr anomaly (Sr/Sr* = SrN/sqrt[PrN*NdN]; N refers to chondrite-normalized values) greater than ~0.7. This observation strongly indicates that the composition of MORB is influenced by the melt-rock reaction taking place in the lower oceanic crust. Furthermore, our findings suggest that evolved melts in equilibrium with clinopyroxene having Sr/Sr* values lower than ~0.7 are less likely to erupt onto the seafloor and are instead trapped within the lower oceanic crust. Oxide gabbronorite is characterized by coarse-granular, pegmatitic textures and exhibits mineralogically and chemically more evolved characteristics compared to olivine gabbro and gabbro. It is inferred that the oxide gabbronorite formed through the in situ freezing of highly evolved melts within a melt-rich layer. Finally, we present a comprehensive model for melt evolution in the lower oceanic crust at the 7°50′S–8°30′S CIR by integrating all petrological and geochemical data obtained from gabbroic rocks, MORB, and olivine-hosted melt inclusions. This holistic model contributes to a better understanding of the intricate processes governing MORB composition in the context of the lower oceanic crust dynamics at slow-spreading ridges. [ABSTRACT FROM AUTHOR]

One of the most significant techniques of heat exchange in manufacturing appliances is convective heat transfer which can be enhanced by porous media and magnetic fields in various applications such as improving dramatically the different thermal equipment performance. This study investigates magnetohydrodynamic Maxwell nanofluid saturated in a porous medium towards convectively heated extending cylinder with higher-order chemical reactions. The ordinary differential equations resolved by using the optimal homotopy analysis method. The impact of various relevant factors on the schemes of velocity, energy, and concentration is drawn via diagrams and discussed physically through graphs, and discussions. The correlation between current and previously published findings is noted for accuracy. It is found that the heat transfer enhances when the Biot number and order of chemical reaction increase. When, the parameter of reaction, magnetic field, permeability and Eckert number increase, the heat transfer diminishes. The rising values of Joule heating, chemical reaction and Biot number rises the mass transfer, but in the opposite direction the mass transfer is reduced as the magnetic parameter, permeability and the order of chemical reaction grow. This study will be helpful in studying the movement of water or oil and gas through the cylindrical tanks. [ABSTRACT FROM AUTHOR]

This paper uses a reactive flow large eddy simulation (LES) and decomposition techniques to study combustion instabilities in a methane–oxygen combustor. This work examines two case scenarios to elucidate the significance of injector–chamber frequency coupling as the cause of thermo-acoustic instability. Initial investigation in a well-known benchmark case of the continuously variable resonance combustor (CVRC) reports the potential instability mechanisms and the role of injector–chamber frequency coupling in thermo-acoustic instability. Subsequently, the multi-element rocket combustor case study identifies the critical resonant modes and highlights potential frequency coupling between the injector and the chamber region. The interplay between longitudinal pressure oscillations in the oxidizer post and transverse pressure waves in the chamber is responsible for the enhanced pressure dynamics in the combustor. The present work uses the dynamic mode decomposition (DMD) technique to reveal the evolution of acoustic modes in the injector and the chamber for CVRC and multi-element combustor. The dominant pressure mode forms found by DMD analysis also showcase the role of injector–chamber frequency coupling in amplified combustion dynamics. The results demonstrate how the predominant cause of combustion instability in rocket combustors can be effectively determined using the high-fidelity LES framework in conjunction with the modal decomposition technique. [ABSTRACT FROM AUTHOR]

Multi‐scale modeling allows the description of real reactive systems under industrially relevant conditions. However, its application to rational catalyst and reactor design is hindered by the prohibitively high computational cost associated with the chemical kinetics on the catalyst scale. Here, the computational cost is drastically reduced by introducing goal‐oriented kernel models that serve as surrogates for the chemical kinetics. This special model type allows for automated training set design and reliable results, even outside the training region. Therefore, it can be envisioned as a plug‐and‐play solution for accelerating reactive flow simulations with guaranteed accuracy. [ABSTRACT FROM AUTHOR]

In today's context of power generation from wind, the demand for reliable and high-performing inverters is on the rise. The quasi-Z-source inverters (q-ZSI) are gaining attention in grid-tied wind power generation systems (WPGS) when compared to conventional inverters for their inherent capability of single-stage power conversion and maximum power point tracking (MPPT) performance. However, the erratic nature of wind speed creates a constant challenge for engineers seeking to optimize the performance of wind turbines (WT). Therefore, this paper suggests a new grey wolf-optimized MPPT (GWO-MPPT) controller for q-ZSI-based grid-tied WPGS, which holds great potential for maximizing the power output of WTs. The conventional MPPT controller used in q-ZSI-based WPGS cannot guarantee stable operation during large variations in wind speed. The GWO-MPPT controller can immediately respond during wind speed variations and trace the maximum power point (MPP) without fluctuations around it, thus improving the MPPT performance. The GWO algorithm estimates the optimum rectifier DC voltage for each wind speed to locate the MPP and subsequently determines the shoot-through duty ratio for the q-ZSI. In addition, this work introduces a decoupling current control strategy supported by dual frequency modulation (DFM) for managing the grid's active and reactive power flows. The functionality of the proposed controllers is rigorously examined using the MATLAB/Simulink tool through extensive simulations. Finally, their practicality is evaluated through an experimental hardware setup. This integrated approach thoroughly investigates the controllers' effectiveness and suitability for practical implementation in WPGS. [ABSTRACT FROM AUTHOR]

In this work, a grid-connected hybrid energy system composed of wind/PV/FC/DG with a HESS based on a battery and supercapacitor. To protect the latter from deep discharge and enhance network flexibility, we use a diesel generator. The objectives of this research are: For generator-side control systems, we apply the TSR strategy for the wind power generator and the FLC strategy for the photovoltaic generator to achieve maximum energy operation. On the management side, we proposed and implemented a new hybrid intelligent energy management strategy based on the FLC-ANN to balance energy supply and demand and increase the life cycle of the proposed system. As for the grid side, the DPC-FLC was applied to control the flow of active and reactive power flowing in the grid. To evaluate the effectiveness of the proposed controllers under changing conditions in energy demand and climate, a simulation test of the proposed system was conducted using the Matlab-Simulink platform. Finally, the results obtained demonstrated the efficiency of the proposed system in terms of the feasibility and effectiveness of the proposed control techniques, in addition to the THD of the network current, which reached 0.34%, which contributes to improving the power quality of hybrid systems. [ABSTRACT FROM AUTHOR]

In recent years, economic and environmental issues have shown the need to enhance the performance of power systems in order to postpone expansion investments. These issues have motivated research studies and technology developments to control the power flow, which allows better use of the current structure. One of these technologies is the Thyristor Controlled Series Compensation (TCSC), which permits a smooth control of the power flow throughout the transmission lines. This paper aims to analyze the performance of a TCSC device in power systems on the optimal reactive power flow point of view. The method uses a genetic algorithm to enhance the performance of power systems by adjusting the voltage of the control buses and the TCSC compensation. The method was tested in two standard IEEE 14-bus and IEEE 118-bus systems in the base case and under contingencies. The results showed that the method improved system performance by decreasing the reactive power loss and enhancing the voltage profile, both in the base case and under contingencies. [ABSTRACT FROM AUTHOR]

Large eddy simulation (LES) coupled with Lagrangian particle simulation (LPS) is applied to investigate high‐speed turbulent reacting flows. Here, LES solves a velocity field while LPS solves scalar transport equations with notional particles. Although LPS does not require sub‐grid scale models for chemical source terms, molecular diffusion has to be modeled by a so‐called mixing model, for which a mixing volume model (MVM), that is originally proposed for an inert scalar in incompressible flow, is extended to reactive scalars in compressible flows. The extended model is based on a relaxation process toward the average of nearby notional particles and assumes a common mixing timescale for all species. LES/LPS with the MVM is applied to a temporally‐evolving compressible turbulent planar jet with an isothermal reaction and is tested by comparing the results with direct numerical simulation (DNS). The results show that LES/LPS well predicts the statistics of mass fractions. As the jet Mach number increases, the reaction progress delays due to the delayed jet development. This Mach number dependence is also well reproduced in LES/LPS. The mean molecular diffusion term of the product calculated as a function of its mass fraction also agrees well between LES/LPS and DNS. An important parameter for the MVM is the distance among particles, for which the requirement for accurate prediction is presented for the present test case. LES/LPS with the MVM is expected to be a promising method for investigating compressible turbulent reactive flows at a moderate computational cost. [ABSTRACT FROM AUTHOR]

We present a new pore‐scale model for multicomponent advective‐diffusive transport with coupled mineral dissolution and precipitation. Both dissolution and precipitation are captured simultaneously by introducing a phase transformation vector field representing the direction and magnitude of the overall phase change. An effective viscosity model is adopted in simulating fluid flow during mineral dissolution‐precipitation that can accurately capture the velocity field without introducing any empirical parameters. The proposed approach is validated against analytical solutions and interface tracking simulations in simplified structures. After validation, the proposed approach is employed in modeling realistic rocks where mineral dissolution and precipitation are dominant at different locations. We have identified three regimes for mineral dissolution‐precipitation coupling: (a) compact dissolution‐precipitation where dissolution is dominant near the inlet and precipitation is dominant near the outlet, (b) wormhole dissolution with clustered precipitation where dissolution generates wormholes in the main flow paths and precipitation clogs the secondary flow paths, and (c) dissolution dominant where all solid grains are gradually dissolved. In the three regimes, the proposed approach provides reliable porosity‐permeability relationships that cannot be described well by traditional macroscale models. We find that the permeability can increase while the overall porosity decreases when the main flow paths are expanded by dissolution and adjacent pore spaces are clogged by precipitation. Key Points: A new pore‐scale model is developed for multicomponent reactive flow with coupled mineral dissolution and precipitationThe proposed model is validated against analytical solutions and reference simulations, and then applied to realistic rocksThree dissolution‐precipitation coupling regimes with different flow patterns and porosity‐permeability relationships have been identified [ABSTRACT FROM AUTHOR]

The formation of new mineral phases in confined environments, especially in porous media, is crucial for various geological processes like mineralization and diagenesis. The nucleation and precipitation of minerals are initiated at the microscale through fluid‐rock interaction, where dissolution of primary phases leads to supersaturated conditions and nucleation and growth of secondary ones. Previous research has focused primarily on either precipitation or nucleation, without fully exploring their combined impact. Our study introduces a computational framework that integrates classical nucleation theory with the micro‐continuum method. We validated our model by comparing with experiments, and discovered that different surface nucleation rate changes the mode of precipitation from a preferential to uniform precipitate textures. Furthermore, our study uncovered that the conventional deterministic precipitation method tends to underestimate the permeability of the porous matrix. In contrast, the new framework significantly improves model accuracy by incorporating preferential precipitation and heterogeneous nucleation. Plain Language Summary: The formation of minerals in confined environments, especially in porous media, is important for both natural processes and industrial applications. The resulting solid phases can greatly affect the porosity and permeability of the porous structure. Many previous studies have focused on either nucleation or precipitation, we still have a limited understanding of how both processes interact at different scales. In this study, we integrated the Darcy‐Brinkman‐Stokes method and classical nucleation theory to investigate the interplay between nucleation, precipitation, species transport, and their impact on permeability. Our findings show that adjusting the surface nucleation rates can change the mode of mineral precipitation from preferential to uniform. We also found that the traditional deterministic precipitation method underestimates permeability in certain scenario. Therefore, considering probabilistic nucleation is crucial when there is preferential precipitation and heterogeneous nucleation on the interfaces between the minerals and surrounding liquid under reactive flow conditions. Key Points: The proposed computational framework focuses on investigating the heterogeneity of nucleation and its effects on mineral precipitationThe new model is validated by comparing with experimental data, demonstrating an agreement in both nucleation morphology and rateThe new model integrates probabilistic nucleation, resulting in a notable enhancement in the accuracy of permeability predictions [ABSTRACT FROM AUTHOR]

The deeper penetration of renewables in the energy mix is an intense requirement in order to reduce global carbon dioxide emissions. In addition, new technologies are being developed, such as electric mobility and Distributed Generation (DG) in urban areas. However, the unpredictable fluctuations in energy generation from roof-installed PVs and the switching operation of their inverters greatly aggravate the already-present grid quality problems. In this paper, the Smart Boiler (SB) concept for grid quality improvement is presented. Furthermore, its experimental verification is implemented on a flexible testbed that accurately emulates several realistic scenarios for the low voltage distribution grid, under complex operating conditions. The proposed low-cost electronic kit, which contains a converter of fairly simple topology and requires connection to the internet, is used to upgrade conventional domestic boilers to smart devices. The SB automatically regulate the local reactive power flow, helping to stabilize the voltage level and suppress the grid current harmonic content, with both services provided in a matter of seconds. The higher the active power consumed and the denser the SB cluster, the wider the beneficial impact on the affected network area. While this service is provided, excess energy generated by PVs is temporarily stored as heat in the boiler tanks, given the users' hot water consumption habits. The whole application, as a powerful demand-side management tool, proves beneficial for both the network operator and the end-user, especially when self-consumption is desirable in order to achieve a Nearly Zero Energy Building. [ABSTRACT FROM AUTHOR]

Scramjet engines represent one of the most promising alternatives to power hypersonic vehicles, although the peculiarities of supersonic combustion raise many challenges. Computational Fluid Dynamics (CFD) simulations can be used to model highly turbulent reactive flows in such complex configurations and avoid expensive experimental campaigns. A particularly challenging aspect when dealing with numerical simulations of turbulent combustion is accurately modelling the interactions between chemistry and turbulence. These interactions can play a significant role in supersonic flows and require an appropriate closure since the conditions encountered in supersonic flows differ from those of conventional combustion devices. For this reason, an assessment of the role of turbulence-chemistry interactions in supersonic combustion is needed. This work evaluates the performance of the Partially-Stirred Reactor (PaSR) closure of the mean chemical source term by performing Reynolds-Averaged Navier–Stokes (RANS) simulations of two selected test cases, namely, the Burrows and Kurkov combustor and the German Aerospace Centre (DLR) scramjet. The PaSR approach requires the definitions of two important quantities: mixing and chemical time scales. While the chemical time scale is related to finite-rate chemistry, supersonic flow conditions can affect the most appropriate definition of the mixing time scale. For this reason, several formulations of the mixing time scale are tested in this work. The PaSR model is validated against experimental data and also compared to the finite-rate approach without turbulence-chemistry interactions (FR/No-TCI) and the Eddy Dissipation Concept (EDC). In the Burrows and Kurkov test case, the PaSR model can accurately predict the main quantities of interest (e.g., temperature and chemical compositions), showing better results than the FR/No-TCI and similar to the EDC model. The validation on the DLR case confirms these trends and highlights the importance of accounting for turbulence-chemistry interaction in supersonic combustion modelling. However, the EDC model is not able to predict a stable ignited flame in the DLR combustor. The presence of recirculation zones near the strut injector of the DLR scramjet can explain the better performance of the PaSR model versions employing the integral-based and geometric mean formulations, which estimate comparable values of the mixing time but higher than those of other time scale approaches considered in this work. • Supersonic combustion is characterised by similar chemical and mixing time scales. • The Partially Stirred Reactor model is suitable for RANS simulations of supersonic combustion. • The model performs better than a laminar finite-rate approach and Eddy Dissipation Concept. • The choice of the mixing time scale affects the Partially Stirred Reactor accuracy. • The most appropriate mixing time scale is selected for two scramjet combustion test cases. [ABSTRACT FROM AUTHOR]

In this article we explore (a) optical and (b) thermochemical properties of reactive hypersonic flows, with an emphasis on oxygen dynamics and time resolved measurement capabilities. First, we discuss experimental and numerical analysis of reactive hypersonic flows of an argon–oxygen mixture over a blunt wedge geometry. The experimental campaign for that geometry uses Michelson interferometry to determine the refractive index of the shock layer. Numerical analysis of these cases reveals that there is dissociation of molecular oxygen in the shock layer. Excellent comparison between numerically predicted and nanosecond sampled experimentally observed refractive index serve as verification of non-equilibrium refractive index theory and the thermochemistry models used in the simulation. Uncertainties and limitations of the interferometry technique are discussed. In addition, we perform subnanosecond sampled femtosecond/picosecond hybrid Coherent anti-Stokes Raman scattering (CARS) spectroscopy behind a hypersonic Mach stem configuration in a pure oxygen flow to demonstrate capabilities to enhance understanding of nonequilibrium vibrational mode contributions to the refractive index. Hybrid CARS gives instantaneous vibrational populations and relevant vibrational temperatures at specific locations downstream of the shock. [ABSTRACT FROM AUTHOR]

Nonlinear heterogeneous reactions are important for simulating dissolution as they involve reactant adsorption, reaction, and product desorption, leading to nonlinear behavior. This study proposes a new curved reaction boundary condition in general form in the lattice Boltzmann framework. This method calculates the unknown distribution functions and the interface concentration using extrapolated distribution functions on actual interface position. Various analytical benchmarks were used to compare this method's accuracy with two available schemes, including Kashani et al. and Huber et al. methods. According to the results, in the simulation of reactant transport on straight and curved surfaces with and without dissolution, errors obtained by the proposed method did not exceed 1.7% in different conditions, while errors of the two other methods were up to 50%. The convergence rate of different methods was determined, and based on the results, the convergence rate of the proposed method was second-order, while the corresponding values for the two other methods were only first-order. The results of different root-finding methods in the proposed method including Bisection, Newton-Raphson, and linear approximation were compared to determine the interface concentration. The results showed that Bisection errors did not exceed 1%. At the same time, using Newton-Raphson and linear approximation led to errors of 12.9% and 25.3%, respectively. The effect of reaction orders on an obstacle dissolved under reactive flows in a channel was investigated. According to the results, in each Damköhler number, increasing the reaction order decreased the dissolution rate; however, increasing the Damköhler number significantly restricted the effect of orders. [ABSTRACT FROM AUTHOR]

The reduction of carbon emissions has become a critical global issue, and the use of monoethanolamine (MEA) solution for CO2 absorption is prevalent in industry. To elucidate the mass transfer mechanisms in reactive multiphase flow, we employed high-speed photography and digital image processing to examine the dynamics and mass transfer behavior of CO2 bubbles in a Hele-Shaw cell. The results indicate that as the MEA solution concentration increases, oscillations during bubble ascent diminish, and the terminal velocity decreases. Based on changes in the mass transfer coefficient, the reaction process can be segmented into a phase of intensified mass transfer, marked by a rapid decrease in bubble equivalent diameter, and a phase of deteriorating mass transfer, where the diameter stabilizes. Additionally, we introduced a dimensionless mathematical model for the Sherwood number based on experimental findings, and its reliability was confirmed. [ABSTRACT FROM AUTHOR]

Background: The mixed convection flow of viscous fluid due to an oscillating plate is inspected. The external heating effects and chemical reaction assessment are predicted. Moreover, the flow applications of the entropy generation phenomenon are claimed. Results: The dimensionless system is expressed in partial differential forms, which are analytically treated with the Laplace scheme. The physical aspects of the flow model are graphically observed. The optimized phenomenon is focused on flow parameters. The results for the Bejan number are also presented. The dynamic of heat transfer and entropy generation phenomenon is observed with applications of Bejan number. Conclusions: It is claimed that an enhancement of entropy generation phenomenon is noticed due to heat and mass Grashof coefficients. The Bejan number declined due to mass Grashof number. Furthermore, the velocity profile boosted due to Grashof constant. [ABSTRACT FROM AUTHOR]

The main aim of this paper is to provide numerical simulation for viscous nanofluid by stretching cylinder using Buongiorno's model. Dissipation, Joule heating and magnetic impact with irreversibility analysis are examined. Furthermore, Brownian movement and thermophoresis diffusion effects are studied. Through constitutive relations, nonlinear equations are obtained. By adopting suitable variables, the partial differential equations are changed to ordinary differential equations. Entropy rate is calculated using thermodynamics second law. ND-solve technique in Mathematica is employed to tackle dimensionless ordinary differential equations. The behavior of flow controlling parameters is examined graphically. Physical quantities are discussed through tables. A decrement in velocity is seen through magnetic effect, while opposite impact is seen for entropy rate. A similar scenario is seen for thermal field through random and thermophoresis variables. Reduction in concentration is seen for reaction parameter and Schmidt number. Important findings are presented. [ABSTRACT FROM AUTHOR]