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The free-surface vortex at the end of tundish casting sequence induces slag carryover into the mold, which can induce reduction in metal yield, deterioration in billet quality, and disruption to production. In this paper, the results of multiphase flow behavior in both tundish and mold during the formation process of free-surface vortex calculated by large eddy simulation (LES) model the RNG k-ɛ model were firstly compared, then the effect of rotating speed of stopper-rod on vortex and mold was numerically investigated based on the LES model. The results showed that the LES model offers a more precise simulation of multiphase flow, providing a better representation of tundish swirl evolution, fluctuations at the steel/slag interface, and slag phase motion. When the rotating speed of stopper-rod is 60 r/min, the fluctuation of mold flux is minimized, with a maximum surface velocity of 0.12 m/s, a slag carryover velocity of 0.122 kg/s at the moment of vortex penetration, and the amount of residual steel is reduced by about 600 kg, the critical height of the 1st and 2nd strands is reduced by 13.5 mm and 15.5 mm, respectively, which performs clear advantage over the schemes of 0, 30, and 90 r/min. The present study can offer theoretical guidance on suppressing free-surface vortex in tundish on the premise of improving the multiphase flow in mold. [ABSTRACT FROM AUTHOR]

In the current study, a three-dimensional mathematical model was established, integrating with the large eddy simulation (LES) turbulent model, the volume of fluid (VOF) multiphase model, and the magnetohydrodynamics (MHD) model to investigate the influence of the mold electromagnetic stirring (M-EMS) on the multiphase flow field in a slab continuous casting mold. The results indicated that the application of M-EMS altered the flow pattern of molten steel in the mold, thereby intensifying the meniscus fluctuation. Moreover, it increased the probability of the slag entrainment, elevating the net slag entrainment rate by nearly ten times. With the increase in current intensity, the stirring effect of M-EMS not only intensified the meniscus fluctuation but also increased the net slag entrainment rate. A user-defined function (UDF) was employed to quantify the number, size, and spatial distribution of entrained slag droplets. The increase in current intensity led to an increase in the number of large-size entrained slag droplets. The greater stirring intensity at a current intensity of 600 A led to the fragmentation of the larger entrained slag droplets into several smaller droplets, thus the proportion of large-size entrained slag droplets was reduced. The stirring effect of the electromagnetic force led to the formation of numerous vortices along the centerline of the mold thickness. Consequently, this phenomenon led to an increase in the occurrence and probability of slag entrainment along the centerline of the mold thickness. Under the influence of M-EMS, the effect of slag viscosity on the multiphase flow field appeared to be less significant, while an increase in viscosity reduced the slag entrainment rate. The submerged entry nozzle angle directly influenced the flow field in the upper circulation, consequently affecting the slag entrainment rate. The size distribution of entrained slag droplets remained unaffected by the slag viscosity and the nozzle angle. [ABSTRACT FROM AUTHOR]

The flow, level fluctuation, and initial solidification in a 1248 × 200 mm2 slab mold of stainless steel under the bifurcated SEN with diverse divergent angle, inclination angle, and immersion depth were numerically discussed and compared in this paper, and the simulation results of flow patterns and level fluctuations were validated by water model experiments. The research outcome indicated that the flow field and level fluctuation obtained through numerical simulation are generally in line with the outcomes observed in water model experiments. When the inclination angles are 0, 8, 12, and 15 deg, the level fluctuations in the mold are 8.18, 15.60, 12.19, and 11.56 mm, while the solidified shell thickness at mold outlet is 12.76, 13.08, 7.24, and 13.96 mm, respectively. When the divergent angle increases range from 0 to 15 deg, the level fluctuation in mold decreases by 5.72 mm, while the shell thicknesses at impact area and mold outlet of the narrow side increase by 3.89 and 2.87 mm, without negative adverse impact on the shell and temperature on the wide face. The SEN immersion depth has minimal infection on the level fluctuation and shell growth in the mold. As the immersion depth increases by 40 mm, the level fluctuation at the steel/slag interface and the shell thickness at the mold outlet decrease by 0.85 and 0.8 mm, respectively. The research outcomes can offer theoretical direction for optimization of level fluctuation and initial solidification behavior in stainless steel slab mold with upward bifurcated SEN. [ABSTRACT FROM AUTHOR]

Strand electromagnetic stirring (SEMS) is widely applied in thin-slab continuous casting to promote the equiaxed crystal ratio (ECR). However, the effects of alternate electromagnetic stirring on the evolution of solidification macrostructure and ECR remain poorly understood. And the formation of the equiaxed crystal region beneath the stand and equiaxed-to-columnar transition (ECT) have been overlooked in most previous models. This study first introduces a novel equiaxed-columnar solidification model to comprehensively analyze the effects of alternate electromagnetic stirring in thin-slab continuous casting. A complete macrostructure feature of the slab, including the equiaxed crystal region beneath the strand, ECT, well-developed columnar dendrites, columnar-to-equiaxed transition, and center equiaxed crystal zone, could be simulated accurately. The multiphase model was validated by the measured ECR and columnar growing direction from a pickling corrosion experiment. Results showed that alternate stirring could improve the ECR effectively. The ECR was increased by 26 pct compared to the one-way stirring when the switching period of alternate stirring was 8–12 seconds. A multi-vortex flow structure was observed in the secondary cooling zone, which could increase the residence time of the molten steel and the nucleation rate. Furthermore, the vortex-shedding behavior of the upper recirculation alleviated the remelting of equiaxed crystals during the sedimentation. The behavior of multiphase flow under alternate SEMS is a novel finding. These preliminary results are encouraging and should be validated in other continuous casting processes. [ABSTRACT FROM AUTHOR]

To achieve the scale development of rare earth electrolytic cells and to improve their current efficiency and life cycle, a bottom cathode rare earth electrolytic cell was put forward. The flow fields of a conventional vertical cathode rare earth electrolytic cell (CVCEC) and a bottom cathode rare earth electrolytic cell (BCEC) were simulated by a multiphase flow model. The VOF model was used to simulating the flow fields of the two types of cells. The simulation results indicate a strong fluid circulation flow between the cathode and anode in the CVCEC, which enhances the convective mass transfer and also affects the trajectory of rare earth metals. The fluid flow between the cathode and anode is relatively gentle for the BCEC, and the possibility of secondary oxidation of rare earth metals is very low. It is speculated that the electrolytic current efficiency of the BCEC is higher. To prove the speculation based on the flow field simulation results, electrolysis experiments were carried out on two types of electrolytic cells. The results show that the current efficiency of the BCEC is about 10 pct higher than that of the CVCEC, which confirms that the BCEC can significantly improve the current efficiency. [ABSTRACT FROM AUTHOR]

An 1/4 ladle water model is build, a differential flow bottom blowing method with different flow ratios is proposed, and an Eulerian multiphase flow model which coupling of the Eulerian model and the Volume of Fluid (VOF) interface tracking method was established to study the flow field, mixing time, slag eyes area and its fluctuation in ladle water model. The result shows that the mixing time increases first and then decreases with the increase of bottom blowing ratio. The mixing time is longest in single nozzle and reaches its shortest at ratio of 2:1. Compared to equal flow and single nozzle, using differential flow can reduce the slag eyes area. The calculated results of mixing time and slag eyes area agree well with the experimental results. Compared to the traditional equal flow bottom blowing method and single nozzle, using the differential flow with a flow ratio of 2:1 can reduce the stirring consumption caused by the collision between two streams, and the range of low-speed eddy current is reduced. The volume average values of turbulent kinetic energy and viscosity under equal flow and 2:1 differential flow are relatively close; after 2:1, they will significantly decrease with increasing bottom blowing ratio, reaching the minimum value during single nozzle. The model has a good capture effect on the sharp interface between water and oil. [ABSTRACT FROM AUTHOR]

A new two-way coupled magnetohydrodynamic (MHD) model considering the dynamics change of electromagnetic force at steel–slag interface was established to investigate the multiphase flow and slag entrapment in slab continuous casting under mold electromagnetic stirring (EMS). The transient turbulent flow and the steel–slag interface behavior were described by solving the large eddy simulation (LES) model and volume of fluid (VOF) model. The level fluctuation, the location, and net mass of slag entrapment were quantitatively evaluated. By comparing the predicted level height within the in-situ measurement, the results show that the two-way coupled MHD model can better reveal the multiphase flow under EMS. The type of slag entrapment is closely related to the flow pattern, the vortex formation is predominant under the lower EMS current, while it changes to the shear-layer instability under the relatively high EMS current, the proportion of vortex formation slag entrapment decreases to 30.7 pct under the EMS current is 600 A. The tendency of net slag entrapment rate is the same as that of level fluctuation, with the increase of EMS current and casting speed, both the level height and net slag entrapment rate decrease firstly and then increase. Therefore, it is necessary to match the casting speed and EMS current to avoid the slag entrapment in actual production. The net slag entrapment rate is 0.034 kg/s, under the condition of 1.2 m/min casting speed and 600 A EMS current. [ABSTRACT FROM AUTHOR]

The lattice‐Boltzmann method (LBM) is becoming increasingly popular for simulating multi‐phase flows on the microscale because of its advantages in terms of computational efficiency. Many applications of the method are restricted to relatively simple geometries. When a more complex geometry is considered—circular and inclined microchannels—some important physical phenomena may not be accurately captured, especially at low capillary numbers. A Y‐Y micro‐fluidic channel, widely used for a range of applications, is an example of a more complex geometry. This work aims to capture the various flow phenomena, with an emphasis on parallel flow and leakage, using the Rothman–Keller (RK) model of the LBM. To this purpose, we modify the forcing term to implement the surface tension for use at low capillary numbers. We compare the simulation results of the RK model with and without the force modification with experiments, Volume of Fluid and the phase field method and observe that the modified forcing term is an improvement over the current RK model at low capillary numbers, and it also captures parallel flow and leakage more accurately than the other simulation techniques. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

It is more difficult to accurately control the cycle fuel mass of a gasoline engine as the injection pressure increases, and the difference in the injection mass flow will become intense due to the machining error of GDI injector structural parameters. In order to guarantee the uniform cycle fuel mass of the GDI injector, this paper investigates the effect of the inlet orifice on the injection mass flow and the sensitivity of inner-flow characteristics in the GDI injector nozzle to the inlet orifice radius by the single factor analysis method. The results show that the local resistance of the injector nozzle will decrease and the discharge coefficient will rise due to the increase in the inlet orifice radius; the sensitivity of cycle fuel mass to the inlet orifice radius is most strong at r = 0.02 mm, and its accuracy should be improved when grinding the chamfer of the nozzle inlet; the sensitivity coefficient of the inlet orifice radius will rise up, and the machining accuracy of the inlet orifice radius should be improved as there is an increase in injection pressure. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Numerical analysis of the sediment erosion of the balance valve in a buoyancy regulation system was performed. A numerical model for the two-phase flow inside the balance valve was constructed based on the discrete phase model. The sediment erosion rate on the balance valve was discussed, and the effects of five parameters were considered. The effects of the sediment concentration and valve opening were found to be significant, while the effects of the pressure difference, sediment density, and size were found to be moderate. The erosion rate, according to the numerical results, increased linearly with the sediment concentration, so long-term operation of a buoyancy regulation system in high-concentration areas should be avoided. The erosion rate was the highest when the valve opening was 46.3%, so half-open operating conditions are not recommended. The erosion rate was proportional to the square root of the pressure difference. However, adjusting the pressure difference may not be an effective method for regulating the total erosion. The superposition of the secondary flow and the main stream caused particles to spiral along with the fluid, resulting in asymmetric erosion at the working edge. The erosion rate on the working edge decreased with the increase in the sediment size. Conversely, the erosion rate on the valve ball surface increased with the sixth power of the sediment size. Considering that large particles are more likely to cause a blockage, it is recommended to install a seawater pretreatment device at the inlet to prevent large sediments from entering the valve and to improve the working life of the buoyancy regulation system. [ABSTRACT FROM AUTHOR]

To investigate the flow characteristics of sieve tray columns with circular downcomers, the Euler–Euler gas–liquid two‐phase flow model is used to simulate a three‐dimensional sieve tray column. Each phase is regarded as an interpenetrating continuum with independent transport equations. The velocity distribution, clear liquid height, and foam layer height are predicted by the model. The correlation is established for predicting the clear liquid height on the sieve tray. The results show the following: (1) The sensitivity of the clear liquid height to the gas phase load is greater than that of the liquid phase load. (2) When the gas–liquid distribution is stable, the flow on the round sieve tray column presents a piston flow pattern. (3) The average liquid holdup of the circular downcomer of the three heights all showed a slow decrease at first, and then an inflection point appeared near the height of 0.02 m, after which the liquid holdup dropped sharply. (4) The established correlation has good predictive performance for calculating the clear liquid height in the column, and the relative error between the calculated value and the actual value is less than 10%. [ABSTRACT FROM AUTHOR]

This paper presents a numerical study of the complex multiphase flow of air, vapor, and particles in an innovative gas cyclone called CAP cyclone. The air–vapor flow is modeled as a mixture by the Reynolds‐averaged Navier‐Stokes equations with the mixture species transport and the Eulerian wall film model using FLUENT. Particle flow is modeled by the Lagrangian particle tracking method and the condensational growth of particle droplets is modeled via a user‐defined function. The model is validated by reaching good agreement with experimental results. Flow field analysis shows that the added vapor does not change the major vortex characteristics in the cyclone, but the vapor distribution is not uniform. The vapor concentration is much higher in the upper part than in the lower part of the cyclone, leading to insufficient condensational growth in the lower part. A secondary vapor injection is proposed to improve the vapor concentration in the lower part, which is shown to be effective in improving the collection efficiency. The model and the results are helpful to the understanding and optimization of the CAP cyclone technology, and also the vapor and particle droplet flow in turbulent flows. [ABSTRACT FROM AUTHOR]

Nowadays, almost all countries in the world are intensifying their search for locally available energy sources to become independent of external supplies. The production of alternative fuels from biomass and waste by thermal treatment or direct use in the combustion process is still the simplest method for fast and cheap heat production. However, the different characteristics of these fuels can cause problems in the operation of the plants, resulting in increased air pollution. Therefore, the analysis of the thermal treatment of solid fuels is still an important issue from a practical point of view. This work aimed to study biomass combustion in a small-scale reactor using the in-house Extended DEM (XDEM) method based on mixed Lagrangian–Eulerian approaches. This was provided by a novel, independently developed coupling computational interface. This interface allows for a seamless integration between CFD and DEM, improving computational efficiency and accuracy. In addition, significant advances have been made in the underlying physical models. Within the DEM framework, each particle undergoes the thermochemical processes, allowing for the prediction of its shape and structural changes during heating. Together, these changes contribute to a more robust and reliable simulation tool capable of providing detailed insights into complex multi-phase flows and granular material behavior. Numerical results were obtained for a non-typical geometry to check the influence of the walls on the distribution of the parameters in the reactor. The results show that XDEM is a very good tool for predicting the phenomena during the thermal treatment of solid fuels. In particular, it provides information about all the moving particles undergoing chemical reactions, which is very difficult to obtain from measurements. [ABSTRACT FROM AUTHOR]

Multiphase fluids are common in many industries, such as oil and petrochemical, and volume fraction measurement of their phases is a vital subject. Hence, there are lots of scientists and researchers who have introduced many methods and equipment in this regard, for example, photon attenuation sensors, capacitance-based sensors, and so on. These approaches are non-invasive and for this reason, are very popular and widely used. In addition, nowadays, artificial neural networks (ANN) are very attractive in a lot of fields and this is because of their accuracy. Therefore, in this paper, to estimate volume proportion of a three-phase homogeneous fluid, a new system is proposed that contains an MLP ANN, standing for multilayer perceptron artificial neural network, a capacitance-based sensor, and a photon attenuation sensor. Through computational methods, capacities and mass attenuation coefficients are obtained, which act as inputs for the proposed network. All of these inputs were divided randomly in two main groups to train and test the presented model. To opt for a suitable network with the lowest rate of mean absolute error (MAE), a number of architectures with different factors were tested in MATLAB software R2023b. After receiving MAEs equal to 0.29, 1.60, and 1.67 for the water, gas, and oil phases, respectively, the network was chosen to be presented in the paper. Hence, based on outcomes, the proposed approach's novelty is being able to predict all phases of a homogeneous flow with very low error. [ABSTRACT FROM AUTHOR]

Advancing the modeling of evaporation and salt precipitation is essential in CO2 storage processes in aquifers. OpenFOAM provides a platform for computational fluid dynamics (CFD) modeling with its open-source C++ object-oriented architecture that can especially be used in the development of fluid flow models in porous media. Some OpenFOAM packages have been developed in this area, and their codes are available for use. Despite this, the existing OpenFOAM literature does not include a model that incorporates multicomponent interactions in multi-phase flow systems, referred to as compositional modeling, at the Darcy scale. This existing gap is addressed in this paper, where a new simple model in OpenFOAM is introduced that aims to model the interaction of CO2 and H2O components in CO2 storage processes in aquifers at the Darcy scale. The model, named compositionalIGFoam, incorporates a compositional solver by extending the impesFoam solver of the porousMultiphaseFoam package, while assuming some simplifications, to account for CO2/water mutual dissolution, relevant to carbon capture and storage (CCS) processes in aquifers. The functionality of the compositionalIGFoam solver was assessed by showcasing its ability to reproduce the outcomes of existing examples. In addition to that, the process of gas injection into a water-saturated core sample was simulated using the developed model to mimic CO2 injection into aquifers. The CMG-GEM commercial compositional simulator was used to compare its results with the coreflood model of this study. Phenomenal agreement was achieved with the GEM model, showing only 1.8% and 0.4% error for both components. This confirms the accuracy and reliability of the developed model. In conclusion, this study enhances the state of the art in porous media modeling using OpenFOAM 10, providing a valuable tool for examining fluid interactions in subsurface environments, especially within the context of CCS processes. [ABSTRACT FROM AUTHOR]

This study presented a comprehensive computational fluid dynamics-based model for fused filament fabrication (FFF) three-dimensional (3D) printing multiphase and multiphysics coupling. A model based on the framework of computational fluid dynamics was built, utilizing the front-tracking method for high precision of multiphase material interfaces, a fully resolved simulation at the mesoscale explores the underlying physical mechanism of the self-supported horizontal printing. The study investigated the influence of printing temperature and velocity on the FFF process, exhibiting a certain self-supporting forming ability over a specific range. The results indicated that during the printing of large-span horizontal extension structures, the bridge deck material transitions from initial straight extension to sagging deformation, ultimately adopting a curved shape. The straight extension distance is inversely proportional to the depth of the sagging deformation. Additionally, the study revealed that printing temperature primarily affected the curing time of the molten material, while printing velocity fundamentally affected the relaxation time of both thermal and dynamic characteristics of the material. [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]

Particle diameters and jet pressure in abrasive water jet (AWJ) are significant jet properties which deserve a better understanding for improving AWJ machining performance. Some influence factors have been verified regarding nozzle wear in abrasive water jet polishing application. A three-dimensional model of a nozzle is established to analyze the influence of internal multi-phase flow field distribution, which is based on Euler-Lagrange methodology. With the increase of jet pressure, the erosion rate decreases; with the increase of the diameter and mass flow rate of the erosion particles, the erosion speed increases as well. When the diameter of the outlet is worn to 1.6 mm, the pressure on the work piece caused by the abrasive water jet increases by more than double compared to the non-worn nozzle; when the diameter of the nozzle outlet is worn to 1.6 mm, the shear force is 2.5 times higher than the shear force when the diameter is 1.0, which means that the jet force is divergent when the diameter is 1.6 mm, and the damage of the work piece is very serious. The obtained results could improve polishing efficiency on the work piece, extend nozzle lifetimes, and guide the future design of AWJ nozzles. [ABSTRACT FROM AUTHOR]

The cellular Ti(C,N)-based cermets were prepared by multiphase flow agglomeration and subsequent vacuum sintering. By precisely controlling the vacuum degree and temperature, the fine particles collided and then agglomerated together through the surface tension of bubbles generated by the dissolved gas in the slurry, forming a multiphase flow with the liquid medium as the slurry dried. Subsequently, the dried powder mixture containing the agglomerates was subjected to pressing and vacuum sintering to obtain cellular cermets. The cellular cermets were analyzed using DSC, XRD, SEM, TEM, and EDS. During the solid-phase sintering stage, the agglomerates were relatively loose and easily to be destroyed, showing large gaps with the matrix, while the gaps gradually decreased and the density slightly increased as the temperature increased. During liquid phase sintering, the grains in agglomerates were further dissolved to gain fully fine-grained agglomerates, and the interface between the agglomerates and the matrix became clear. Finally, a dense sintered body with cellular structure in which agglomerates were dispersed in the matrix was formed. Furthermore, agglomerates were mainly composed of grains with black core-gray rim and grains without obvious core/rim structure, forming distinct interfaces with the coarse-grained matrix. The cellular Ti(C,N)-based cermets exhibited superb mechanical properties, with TRS of 2184 ± 30 MPa, fracture toughness of 9.01 ± 0.3 MPa m1/2, and hardness of 93.4 ± 0.2 HRA, making them superior to traditional Ti(C,N)-based cermets. [ABSTRACT FROM AUTHOR]

Aerosol jet printing offers high resolution, broad materials compatibility, and digital patterning for flexible, conformal, and hybrid electronics. However, limited throughput, instability, and complex optimization requirements inhibit translation to industrial applications. An in‐line heater integrated on a custom printer is demonstrated to modulate droplet evaporation in the aerosol phase, thereby decoupling the deposition rate of functional solids and liquid ink to enable taller, narrower features with aspect ratios reaching 0.29 for a single line. Heating the printhead from room temperature to 80 °C reduced the sensitivity of resolution to deposition rate by ≈90%, improving reliability. With this strategy, increasing the linear deposition rate by 10x results in a modest increase of 27% in line width, compared to a four‐fold increase without heating, permitting higher throughput without sacrificing print quality. Providing a control for in‐line drying independent of ink formulation enables rapid, straightforward design of new materials and processes. This ability to engineer drying of droplets prior to impingement provides a versatile tool to meet complex fabrication challenges, as demonstrated here for both high aspect ratio printing and conformal patterning on rough and three‐dimensional surfaces. [ABSTRACT FROM AUTHOR]

In this paper, a numerical framework for modelling multiphase flows with interface correction is proposed. In original Volume-of-Fluid method, the interface smearing may appear since the interface profile deviates from its equilibrium state, especially in the simulations of complex interface deformation. To solve this problem, a novel correction step is introduced into the procedure after solving the volume fraction transport equation, and this step just works on the region of phase interface. The difference between the current method and the previous work is that the correction coefficient can be adjusted adaptively with the gradient of normal velocity at the interface, which is strongly correlated to the intensity of interface smearing and changes with the computational time and interface position. The validation computations are performed for bubble deformation (initial shapes of two-dimensional four-lobed-star and three-dimensional (3D) box with holes), bubble rising in a channel and Rayleigh–Taylor instability problems (Reynolds number of 100 and 1000). The obtained results show that the unphysical phenomenon of interface smearing is suppressed effectively, and the interface sharpness is improved greatly by the present method. In addition, the mass of bubble deformation by the original method will decrease by 13.3%. While these results obtained by the present method are in good agreement with the analytical solutions or published data. [ABSTRACT FROM AUTHOR]

Reservoir simulation is crucial for understanding the flow response in underground reservoirs, and it significantly helps reduce uncertainties in geological characterization and optimize methodologies for field development strategies. However, providing efficient and accurate solutions for the strong heterogeneity remains challenging, as most of the discretization methods cannot handle this complexity. In this work, we perform a comprehensive assessment of various numerical linearization techniques employed in reservoir simulation, particularly focusing on the performance of the nonlinear solver for problem dealing with fluid flow in porous media. The primary linearization methods examined are finite difference central (FDC), finite forward difference (FDF), and operator-based linearization (OBL). These methods are rigorously analyzed and compared in terms of their accuracy, computational efficiency, and adaptability to changing reservoir conditions. The results demonstrate that each method has distinct strengths and limitations. The FDC method is more accurate particularly in complex simulations where strong heterogeneity are introduced but is generally slower in convergence. The OBL on the other hand, is more efficient and converges quickly, which makes it suitable for scenarios with limited computational resources and simple physics, while the FDF method provides a balanced combination of precision and computational speed, contingent upon careful step size management of the derivative estimations. This paper aims to guide the selection of appropriate linearization techniques for enhancing nonlinear solvers' accuracy and efficiency in reservoir simulation. [ABSTRACT FROM AUTHOR]

Bubble curtains are linear multiphase plumes that are used in industry and engineering to reduce diffusive flows between two zones. The circulating shear flow generated by the bubble plume can effectively create a particle barrier in the water; thus, it is also widely used to suppress the diffusion of suspended particles during dredging operations. To clarify the interaction mechanism between the bubble curtain and suspended particles under pressure-driven flow, experimental studies and numerical simulations were conducted to investigate the particle dynamics in the flow field around the bubble curtain. In this study, we established a formal analogy between a bubble curtain and an air curtain and qualitatively identified four typical distribution zones of the particles in the flow field. Based on the quantitative measurements and theoretical considerations, the optimal operating conditions and the upper limit of effectiveness of the bubble curtain were determined. In addition, the blocking behavior and efficiency of bubble plumes on particles with different R e U and F r U g numbers and different particle properties were simulated via the computational fluid dynamics discrete element method (CFD DEM) numerical simulation method. [ABSTRACT FROM AUTHOR]

In the numerical simulations of multi-phase flow using Volume-of-Fluid (VOF) method, the calculation of the interface normal is a crucial point. In this paper, a machine learning method is used to develop an artificial neural network (ANN) model to make more accurate prediction of the local normal vector from neighboring volume fractions. Spherical surfaces with different radii are intersected with a structural background grid to generate 84328 groups of data: 3×3×3 neighboring volume fractions are used as input, and normal vector as output. Using 90% data as training dataset, the ANN model is well trained by optimizing the number of hidden layers and the number of neurons on each layer. Using the remaining 10% data, normal predictions are made using ANN-VOF and the most used YOUNG and HEIGHT-FUNCTION methods. The RMSE of the ANN-VOF/YOUNG/ HEIGHT-FUNCTION methods are 0.008/0.022/0.045 respectively. In the reconstruction of a sinusoidal surface, the MSE of the ANN-VOF/YOUNG/ HEIGHT-FUNCTION methods are 0.008/0.018/0.041. It is demonstrated that the ANN-VOF method has better performance for interface normal prediction. The proposed method has a simple computational logic and does not need to deal with complex geometric topology, which lays the foundation for application in other more complex grids. [ABSTRACT FROM AUTHOR]

Understanding droplet sizes is crucial for modeling gas–liquid annular flow and has many applications across various industries. This paper presents a comprehensive review and analysis of experimental data on droplet-size characteristics in gas–liquid annular flow from the open-source literature. The existing models for droplet-size predictions are evaluated against experimental data. Based on the data analysis, we propose two new correlations to predict the maximum droplet diameter and Sauter mean droplet diameter. Model evaluation and parametric study show that the new correlations capture the effects of fluid properties and flowing conditions on the droplet diameters well, outperforming other existing models. The average absolute relative errors are reduced to 14.8% and 29% for the maximum droplet diameter and the Sauter mean droplet diameter, respectively. [ABSTRACT FROM AUTHOR]

To design the two-dimensional structural parameters of the core throttling component, i.e., the perforated plate for a liquid nitrogen (LN2) balanced flowmeter, this paper presented an orthogonal experiment scheme with three parameters, three factors, and three interactions, combined with the three-dimensional CFD numerical simulation. The constructed mixture multi-phase flow numerical model considers the complex cavitation effect of LN2 with a thermal effect. A DN40 balanced flowmeter and an LN2 flowrate test setup based on a standard flowmeter were constructed, and the measured flowrate data were used to evaluate the CFD model. Based on the optimized two-dimensional structure and the validated numerical model, the influence of the three-dimensional thickness of the perforated plate on the flow and pressure drop coefficient was investigated. It was found that there are two throttling forms as the thickness increases, resulting in two pressure-changing characteristics. The formation mechanism was explained by analyzing the turbulence intensity distribution. Finally, the final flow coefficient, pressure drop coefficient, and upper limit of measurement due to the cavitation were analyzed and obtained. The results provide a feasible parameter design method for the cryogenic balanced flow meters. [ABSTRACT FROM AUTHOR]

In this paper, we present an efficient, robust, and unconditionally energy stable second-order scheme for solving the Cahn-Hilliard-Brinkman (CHB) model, which mathematically describes multiphase flow in porous media. Solving the CHB model is significantly challenging due to its high coupling and nonlinearity. Here, we utilize the scalar auxiliary variable (SAV) method to handle the nonlinear term in the Cahn-Hilliard system, followed by decoupling the model through the implicit-explicit (IMEX) Crank-Nicolson approach. Our constructed scheme employs an adaptive time step, enhancing the robustness of the scheme compared to a fixed time step. The unconditional energy stability of our scheme that integrates artificial stabilized term, is assured easily owing to the SAV method and is theoretically proven in the paper. Finally, numerical experiments employing the Fourier pseudo-spectral method to discrete the spatial variables were conducted in two-dimensional space to validate the numerical accuracy and efficiency of the proposed approach. [ABSTRACT FROM AUTHOR]

Aiming at the problem of start-up failure caused by icing during the cold start of proton exchange membrane fuel cell, COMSOL Multiphysics software is used to establish a cold start transient model of three-dimensional multiphase flow with multi-physics field coupling for proton exchange membrane fuel cell. Through the cold-start model simulation, the effects of the initial membrane water content on the current density, icing rate, temperature and other characteristics of the battery cold-start are investigated. The numerical results show that the higher the initial water content, the greater the initial current density and a faster temperature rises. However, it is accompanied by a larger icing rate and earlier icing time, which leads to a faster decline in battery performance. Lower initial water content is helpful to delay icing, and the battery temperature rises higher, which is more beneficial to cold start. [ABSTRACT FROM AUTHOR]

The heat transfer phenomenon on the multiphase flows plays an imperative role in several biological and industrial processes, like the oil production industries, catalytic reactors, energy losses in several thermal systems, energy storage, paper manufacture, and heat exchanger systems. Therefore, this study scrutinized the heat transfer characteristic between two uniform boundary layer shear flows with different strengths flowing in the same direction. This problem involves the simulation of the convergence of boundary layers with varying shear strengths. The nonlinear differential system is scrutinized and converted into dimensionless ordinary differential equations by employing appropriate dimensionless variables. The resulting set of highly nonlinear ordinary differential equations is resolved numerically utilizing the Matlab solver "bvp4c." The resulting numerical solutions are used to construct graphs that illustrate and elucidate the impact of numerous physical parameters on flow patterns. For both fluids, results for the Nusselt number and shear stress are also presented graphically for various parameters. The acquired results demonstrate that the velocity profile upsurges for both upper and lower fluids by enhancing the shear parameter. Furthermore, the number of streamlines is enhanced by augmenting the values of the viscosities ratio parameter. The present problem applies to the trailing edge flow over a thin airfoil with camber. [ABSTRACT FROM AUTHOR]

Stable-state numerical simulations of the condensation heat transfer properties of the novel refrigerant NCUR01 (R1234ze(E) and R152a in a mass ratio of 4:6) have been performed using the volume of fluid (VOF) multiphase flow model. The findings demonstrate that as mass flux rises, the working substance's fluid velocity increases at the same location within the tube, boosting the condensation heat transfer coefficient in the process. The condensation heat transfer force is strengthened by an increase in heat flux, which raises the condensation heat transfer coefficient. On the other hand, when the saturation temperature rises, the condensation heat transfer coefficient falls. [ABSTRACT FROM AUTHOR]

Inertial focusing in curved microfluidic ducts exploits the interaction of the drag force from the Dean flow with the inertial lift force to separate particles or cells laterally across the cross-section width according to their size. Experimental work has identified that using a trapezoidal cross section, as opposed to a rectangular one, can enhance the sized based separation of particles/cells over a wide range of flow rates. Using our model, derived by carefully examining the way the Dean drag and inertial lift forces interact at low flow rates, we calculate the leading order approximation of these forces for a range of trapezoidal ducts, both vertically symmetric and nonsymmetric, with an increasing amount of skew towards the outside wall. We then conduct a systematic study to examine the bifurcations in the particle equilbira that occur with respect to a shape parameter characterizing the trapezoidal cross section. We reveal how the dynamics associated with particle migration are modified by the degree of skew in the cross-section shape, and show the existence of cusp bifurcations (with the bend radius as a second parameter). Additionally, our investigation suggests an optimal amount of skew for the trapezoidal cross section for the purposes of maximizing particle separation over a wide range of bend radii. [ABSTRACT FROM AUTHOR]

For multiphase batch process, the characteristics of process data under various batches differ. Consequently, the soft sensor model built for a particular working condition is inapplicable to other working conditions. Besides, each batch can be divided into several phases whose characteristics are probably different. To address the above problems, a soft sensor model based on phase division and transfer learning strategy is proposed. First, transfer learning strategy is adopted to construct a soft sensor model applicable to various working conditions. Specifically, geodesic flow kernel based on linear local tangent space alignment (LLTSA-GFK) algorithm is designed. By projecting process data to the common manifold subspace, the distribution difference of data between various batches is reduced and the performance of the soft sensor model is enhanced. In addition, sequence-based fuzzy clustering and just-in-time learning (JITL) are adopted to solve the multistage characteristic for batch process. The root-mean-square error (RMSE), coefficient of determination (R 2) , and mean absolute error (MAE) are adopted to compare the conventional soft sensing approach (i.e., partial least-square regression based on JITL, support vector regression, and back propagation neural network) with the proposed approach. The superiority of the proposed model is verified by a fed-batch penicillin fermentation process. [ABSTRACT FROM AUTHOR]

Hydrate formation in foam drainage gas recovery wells and the shut in accidents caused by plugging have become an important problem that restricts the safe production of natural gas. The blockage and accumulation of hydrates is a gradual problem. This research goes beyond predicting the formation of hydrates and delves deeper into examining the rate of hydrate formation and the degree of pipeline blockage at different wellbore locations. First, the temperature model, pressure model, multiphase flow model, and hydrate plugging model of hydrate formation process are established from the equations of mass conservation, energy conservation, and momentum conservation. Second, an iterative approach is employed to solve the model, with a maximum error of 6.86% in model validation. Finally, sensitivity analysis shows that wellhead temperature, wellhead pressure, and foam viscosity have different effects on hydrate formation, maximum plugging position, and plugging degree. At the same time, combined with the actual drainage and gas production process, and the characteristics of hydrate blockage, proposed hydrate prevention measures can be taken to achieve safe production of natural gas. The research results indicate that a decrease in temperature signifies an increase in undercooling, resulting in an accelerated rate of hydrate formation and an elevated risk of hydrate blockage. The decrease in wellhead pressure leads to a decrease in the rate of hydrate formation and an increase in production, which is beneficial for the hydrate prevention. However, larger pressure differences and gas production rates will put higher requirements on equipment such as well control devices. An increase in foam viscosity will lead to increased pressure, foam compression, reduced drainage capacity, and intensified hydrate generation. Therefore, foam viscosity should be kept as small as possible to keep the foam stable. [ABSTRACT FROM AUTHOR]

Fluid dynamics models complement expensive experiments with limited measurement accuracy that investigate the mass transport in PEM water electrolysis. Here, a first-principle microscale model for oxygen transport is successfully validated that accounts for (1) uncertain transport processes in catalyst layers, (2) numerically challenging capillary-dominated two-phase flow and (3) bubble detachments in channels. We developed algorithms for the stochastic generation of geometries and for the coupling of flow and transport processes. The flow model is based on the volume of fluid method and reproduces experimentally measured pressure drops and bubble velocities within minichannels with a 30% and 20% accuracy, respectively, provided that the capillary number is above 2.1 × 10−7. At lower capillary numbers, excessive spurious currents occur. Correspondingly, two-phase flow simulations within the porous transport layers are stable at current densities above 0.5 A cm−2 and match operando gas saturation measurements within a 20% margin at relevant locations. The simulated bubble detachments occur at pore throats that agree with porosimetry and microfluidic experiments. The presented model allows explaining and optimizing mass transport processes in channels and porous transport layers. These were found to be negligibly sensitive to transport resistances within the catalyst layer, providing information on boundary conditions for future catalyst layer models. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Guangxi Normal University - Natural Science Edition is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soil salinization poses a significant threat to agricultural production in Portugal. Collaborative research spanning three decades with the U.S. Salinity Laboratory in Riverside, California, has been instrumental in advancing our understanding of this issue. This study provides a concise overview of the causes of soil salinization in Portugal, focusing on ongoing efforts to comprehensively address this challenge. Key advancements highlighted in this study encompass the meticulous characterization of soil hydraulic and solute transport parameters, the application of cutting‐edge modeling tools for water flow and solute transport in diverse agricultural systems, and the utilization of innovative proximal and remote sensing methods for mapping soil salinity. Noteworthy results and practical implications of these advancements underscore their relevance in real‐world scenarios. While celebrating these achievements, the study emphasizes the current nature of the ongoing research, highlighting the dynamic landscape of soil salinization. The study underscores the imperative need for further advancements to effectively cope with soil salinization, especially in anticipation of the intensification of agricultural practices and the looming impacts of climate change. This comprehensive overview not only encapsulates past achievements but also sets the stage for future research endeavors in mitigating the pervasive effects of soil salinization on agricultural sustainability in Portugal. Core Ideas: Three decades of studies on soil salinization in Portugal are reviewed, with an overview of the extent and causes.Studies were started by characterizing soil hydraulic and solute transport parameters of Portuguese soils. They then extended to water flow and multicomponent solute transport modeling using the HYDRUS software package.Mapping of soil salinity using proximal and remote sensing methods is the most recent advance.Several research developments are discussed as well as priorities for the coming years. [ABSTRACT FROM AUTHOR]

Jet fuel in aircraft fuel tanks moves due to acceleration resulting from maneuvers. The movement mentioned here directly impacts the Center of Gravity (CG). The aircraft's flight mechanics are significantly affected by the deviation of its CG on the aircraft body, and excessive deviation is undesirable. Preventing CG deviation is achieved by designing various baffles within the fuel tank. In this study, design details of the baffles were investigated with the help of an artificial neural network (ANN) model, 1D simulations, and computational fluid dynamics (CFD) calculations. The 1D simulations, which model the fuel movement, were used to understand the general behavior of the fluid in the tank. CFD calculations simulating turbulent fluid flow in three dimensions were used to confirm the results of the 1D simulations and provide more detailed information. A simulation set is created utilizing five parameters: barrier usage, volume fraction, cutout diameter, number of cutouts, and cutout location. Compared to the barrierless design, the barrier usage as a parameter changes either on baffle number 1, 3, and 6, or on baffle number 2, 4, and 7. The fuel volume fraction parameter accounts for 30%, 45%, and 60% of the interior volume. The diameters of the cutout holes vary between 30 mm and 156 mm and are used as categorized among the baffles. Cutout holes are applied on baffles in single, twin, and triplet forms and their locations are subjected to a divergence of either −20 mm or +20 mm from the z-axis. Based on these parameters, the maximum deviation and the retreat time of CG constitute the output parameters. The importance of the input parameters on the outputs was obtained with the help of an ANN algorithm created from the results of all possible combinations of a sufficient number of 1D simulations. To obtain more detailed results and confirm the importance of input parameters on outputs, selected cases were simulated with CFD. As a result of all analyses, it was revealed that barrier usage is the most dominant input parameter on CG deviation followed by volume fraction, cutout hole diameter, cutout divergence, and finally, the number of cutout holes. This study identifies the dominant input parameters to control fuel sloshing, specifically CG deviation and retreat time in the fuel tank, and proposes baffle designs to promote robust flight stability. [ABSTRACT FROM AUTHOR]

Simulation of subsurface energy system involves multi-physical processes such as thermal, hydraulical, and mechanical (THM) processes, and requires a so-called THM coupled modeling approach. THM coupled modeling is commonly performed in geothermal energy production. However, for hydrocarbon extraction, we need to consider multiphase flow additionally. In this paper, we describe a three-dimensional numerical model of nonisothermal two-phase flow in the deformable porous medium by integrating governing equations of two-phase mixture in the porous media flow in the reservoir. To account for inter-woven impacts in subsurface conditions, we introduced a temperature-dependent fluid viscosity and a fluid density along with a strain-dependent reservoir permeability. Subsequently, we performed numerical experiments of a ten-year water flooding process employing the open-source parallelized code, OpenGeoSys. We considered different well patterns with colder water injection in realistic scenarios. Our results demonstrate that our model can simulate complex interactions of temperature, pore pressure, subsurface stress and water saturation simultaneously to evaluate the recovery performance. High temperature can promote fluid flow while cold water injection under non-isothermal conditions causes the normal stress reduction by significant thermal stress. Under different well patterns the displacement efficiency will be changed by the relative location between injection and production wells. This finding has provided the important reference for fluid flow and induced stress evolution during hydrocarbon exploitation under the environment of large reservoir depth and high temperature. [ABSTRACT FROM AUTHOR]

A one‐dimensional (1D) multifluid population balance model approach is presented as a compromise between computational effort and accuracy. The approach is used to test process scenarios, perform sensitivity analysis, and provide a reliable reactor scale‐up and optimization tool. The article focuses on a mini‐plant batch bubble column, where the scale‐up behavior in terms of bubble column height, gas flux, and composition of the liquid phase is investigated. Although simplifications were made, the model requires calibration to experimental data using different calibration methods. An optimal calibration procedure is found that minimizes experimental effort while maximizing scalability. The model was tested on various liquid‐phase compositions, and it was found to reproduce experimental data accurately. However, the model cannot reproduce flow regime changes and does not perform well across substance systems. The study shows that the applied 1D multifluid population balance approach is a valuable and reliable tool in multiphase reactor scale‐up and optimization. [ABSTRACT FROM AUTHOR]

The purpose of this work was to test a new setup to pump water with entrained air for application in gas fermentation. A mixed flow, where gas is contained in a liquid to be pumped, rapidly reduces the efficiency of a conventional pump, due to the compressibility of the gas. It is not always possible to degas the fluid, for instance in gas fermentation, which is preferably carried out in tubular reactors (loop fermenters) to achieve a high conversion rate of the gaseous feedstocks. Method: In this work, a rim-driven thruster (RDT) was tested in a lab-scale, cold flow model of a loop reactor with 5–30% (by volume) of gas fraction (air) in the liquid (water) as alternative propulsion element (6 m total pipe length, ambient temperature and pressure). As a result, it was found that the RDT, in connection with a guiding vane providing swirling motion to the two-phase fluid, could pump a mixed flow with up to 25.7% of gas content (by volume) at atmospheric pressure and 25 °C and 0.5 to 2 m/s flow speed. In conclusion, an RDT is advantageous over a classic propulsion element like a centrifugal pump or axial flow pump for transporting liquids with entrained gases. This article describes the potential of rim-driven thrusters, as known from marine propulsion, in biotechnology, the chemical industry, and beyond, to handle multiphase flows. [ABSTRACT FROM AUTHOR]

Accurately and instantly estimating the hydrodynamic characteristics in two-phase liquid–gas flow is crucial for industries like oil, gas, and other multiphase flow sectors to reduce costs and emissions, boost efficiency, and enhance operational safety. This type of flow involves constant slippage between gas and liquid phases caused by a deformable interface, resulting in changes in gas volumetric fraction and the creation of structures known as flow patterns. Empirical and numerical methods used for prediction often result in significant inaccuracies during scale-up processes. Different methodologies based on artificial intelligence (AI) are currently being applied to predict hydrodynamic characteristics in two-phase liquid–gas flow, which was corroborated with the bibliometric analysis where AI techniques were found to have been applied in flow pattern recognition, volumetric fraction determination for each fluid, and pressure gradient estimation. The results revealed that a total of 178 keywords in 70 articles, 29 of which reached the threshold (machine learning, flow pattern, two-phase flow, artificial intelligence, and neural networks as the high predominance), were published mainly in Flow Measurement and Instrumentation. This journal has the highest number of published articles related to the studied topic, with nine articles. The most relevant author is Efteknari-Zadeh, E, from the Institute of Optics and Quantum Electronics. [ABSTRACT FROM AUTHOR]

An algorithm based on continuous measurement of multiphase flows of oil well production has been designed to improve the efficiency of the technical control of oil production processes in the field. Separation-free, non-contact measurement of multiphase flows of oil well products allows increasing the efficiency of managing oil production processes in the field. Monitoring the current density using radioisotope measuring transducers (RMTs) allows obtaining information about the structure of the flow in the form of the distribution of gas inclusions and the speed of movement of liquid and gas in a two-phase flow. Fluid velocity measurement is based on digital processing of RMT signals, applying a continuous or discrete undecimated wavelet transform to them, and assessing the cross-correlation of wavelet coefficients in individual subspaces of the wavelet decomposition. The cross-correlation coefficients of two RMT signals located at a base distance, calculated in the subspaces of the wavelet decomposition, characterize the speed of movement of gas bubbles of different sizes in a vertical pipe. The measurement assumes that the velocity of the liquid phase of the oil flow in a vertical pipe mainly corresponds to the velocity of small bubbles. This speed should be determined by the maximum cross-correlation of wavelet coefficients in the corresponding decomposition subspace. Computer modeling made it possible to evaluate the characteristics of the algorithm for controlling the speed of liquid movement in the gas–liquid flow of oil well products and determine the mass flow rate of the liquid and the relative value of the gas content. The implementation of the algorithm in a multi-channel version of the device allows monitoring an entire cluster of wells in the field. [ABSTRACT FROM AUTHOR]

The side-blown smelting process is becoming popular in the modern metallurgical industry due to its large potential for dealing with complex materials. To further enhance its efficiency, it is essential to comprehensively understand the complex gas–liquid flow behavior in the smelting bath. In this study, the volume-of-fluid method is employed to establish computational fluid dynamics modeling on a 1:5 scaled model of a side-blown furnace. The simulation was validated against the experimental results. Notably, the influences of the nozzle's submerged depth, injection velocity, and angle were systematically investigated. The results show that increasing the injection velocity from 29.44 to 58.88 m/s resulted in 52.97%, 116.67%, 500.00%, and 5.88% increases in the interface area, liquid velocity, liquid turbulent kinetic energy, and gas penetration depth, respectively. The maximum gas–liquid interface area, gas penetration depth, velocity, and turbulence of the liquid were found at an injection angle of 30°. Furthermore, increasing the submerged depth increased the interface area and the velocity of the liquid but decreased the turbulent kinetic energy of the liquid. Overall, increasing the injection velocity is considered a more effective measure to strengthen the smelting intensity. [ABSTRACT FROM AUTHOR]

Amid the escalating global demand for raw materials, the gradual exhaustion of terrestrial mineral resources, and the rise in extraction costs and energy consumption, the development of deep-sea mineral resources has become a focal point of international interest. The pipeline lifting mining system, distinguished by its superior mining efficiency and minimized environmental impact, now accounts for over 50% of the total energy consumption in mining operations. Serving as the "heart" of this system, the deep-sea lifting pump's comprehensive performance (high pressure tolerance, non-clogging features, elevated lift capacity, wear resistance, corrosion resistance, and high reliability, etc.), is critical to transport efficiency, operational stability, and lifespan of the mining system. As a mixed transport pump for solid and liquid media under extreme conditions, its internal flow structure is exceedingly complex, incorporating gas–liquid–solid multiphase flow. A precise understanding of its internal flow mechanisms is essential for breaking through the design limitations of deep-sea lifting pumps and enhancing their operational stability and reliability under various working conditions and multiphase media, thereby providing technical support for advancing global marine resource development and offshore equipment upgrades. This paper comprehensively reviews the design theory, optimization methods, numerical simulations, and experimental studies of deep-sea lifting pumps. It discusses the application of various design optimization techniques in hydraulic lifting pumps, details the multiphase flow numerical algorithms commonly used in deep-sea lifting pumps along with their modified models, and summarizes some experimental methodologies in this field. Lastly, it outlines the forthcoming challenges in deep-sea lifting pump research and proposes potential directions to promote the commercial development of deep-sea mining, thereby offering theoretical and engineering support for the development of deep-sea mining slurry pumps. [ABSTRACT FROM AUTHOR]

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A 3D mathematical model was proposed to investigate the molten steel–slag–air multiphase flow in a two-strand slab continuous casting (CC) tundish during ladle change. The study focused on the exposure of the molten steel and the subsequent reoxidation occurrence. The exposure of the molten steel was calculated using the coupled realizable k–ε model and volume of fluid (VOF) model. The diffusion of dissolved oxygen was determined by solving the user-defined scalar (UDS) equation. Moreover, the user-defined function (UDF) was used to describe the source term in the UDS equation and determine the oxidation rate and oxidation position. The effect of the refilling speed on the molten steel exposure and dissolved oxygen content was also discussed. Increasing the refilling speed during ladle change reduced the refilling time and the exposure duration of the molten steel. However, the elevated refilling speed enlarged the slag eyes and increased the average dissolved oxygen content within the tundish, thereby exacerbating the reoxidation phenomenon. In addition, the time required for the molten steel with a high dissolved oxygen content to exit the tundish varied with the refilling speed. When the inlet speed was 3.0 m·s−1 during ladle change, the molten steel with a high dissolved oxygen content exited the outlet in a short period, reaching a maximum dissolved oxygen content of 0.000525wt%. Conversely, when the inlet speed was 1.8 m·s−1, the maximum dissolved oxygen content was 0.000382wt%. The refilling speed during the ladle change process must be appropriately decreased to minimize reoxidation effects and enhance the steel product quality. [ABSTRACT FROM AUTHOR]