Search

We consider the effect that an upstream cylinder has on the effective inertial collection efficiency of a downstream cylinder. We consider an initially uniform distribution of particles moving past a cylindrical fiber in a potential crossflow and numerically calculate the resulting particle distribution far downstream of the fiber using finite differences. We then investigate the effect that the downstream distribution of particles has on the effective inertial collision efficiency of a downstream test cylinder oriented parallel to the first. We show that the effective collision efficiency of the test cylinder depends on its relative offset in the transverse direction (normal to the flow) with respect to the upstream cylinder. For relatively small offsets there is complete shielding, and no particles collide with the test cylinder. As the offset increases, a growing effective collision efficiency is observed leading to a significant enhancement relative to the collision efficiency of an isolated cylinder for intermediate offsets and Stokes numbers close to unity. Importantly, we observe relative gains in effective collision efficiency above 100% for a range of Stokes number and offset values. For larger offsets and Stokes numbers, the effect of the upstream cylinder on the effective collision efficiency of the test cylinder decreases and eventually becomes negligible. Detailed results are provided for Stokes drag acting on the particles and we also show that a non-linear drag has negligible effect on the observed trends for the conditions relevant to filtration systems. These results suggest that the arrangement of fibers has a substantial effect on inertial particle impaction even when neighboring fibers do not alter the flow field around each individual collector. Moreover, periodic arrangements with specific orientations with respect of the flow could lead to a significant enhancement of the inertial collision of particles on an array of collectors, thus contributing towards a better filtration performance.

A novel tribologic system was developed in which volatile lubricants (carbon dioxide-CO2 or nitrogen-N2) were used as a substitute for mineral oil-based lubricants in deep drawing processes. This process allows an intermediate medium to be introduced into the tool contact surfaces under high pressure by flow-optimized, laser-drilled microholes. This eliminates the need for subsequent cost-intensive cleaning processes as volatile lubricants evaporate while expanding to ambient pressure without leaving any residue. This article gives an overview of the current findings to enable and characterize the novel tribologic system. The areas of microhole laser drilling by ultrashort pulsed laser radiation, characterization of the novel tribologic system and realization of the system using a prototype tool will be described., Deutsche Forschungsgemeinschaft, Projekt DEAL

Particle Impact Drilling (PID) is a new technology to effectively improve the rate of penetration (ROP) for oil and gas drilling in hard and strongly abrasive formations. In this paper, numerical simulation method is used to analyse the motion characteristics and the modulation method of particle swarm in high-pressure tank for the particle injection system based on differential pressure ejection in PID. The numerical simulation results show that: when there is no modulation elements, the motion of particle swarm in the high-pressure tank follows an asymmetric funnel flow with pulsating state, which could be divided into vertical flow domain, fast flow domain, slow flow domain and stagnation domain. The unstable dynamic arching effect of the funnel flow, the viscous effect of the liquid bridge force and the collapsing effect of the particle swarm could probably lead to the blockage of the discharge port of the high-pressure tank. When the semiapex angles of the high-pressure tank decreases, the volume flow rate of particles increases and the stagnation domain becomes smaller, but it becomes easier to form arching and blockage. The modelling results indicate that the pulsation of the funnel flow is minimum when the semiapex angle is 45° without the mutilation element, which means the funnel flow of the particle swarm is relatively stable. By introducing a conical modulating element above the discharge port, the unstable funnel flow of the particle swarm could be transformed to an overall uniform flow. The modelling results indicate that the installation height of the modulation element has the greatest influence on the pulsation degree. The optimized parameters for the conical modulation element based on numerical modelling tests are 70° for the vertex angle, 35 mm for the length of the flank and 70 mm for the installation heigh.

This paper deals with the exergy analysis of two experimental prototypes consisting of indirect evaporative cooling systems with different constructive characteristics. Both prototypes have been designed and manufactured in the Thermal Engineering Laboratory of the University of Valladolid. They are made of polycarbonate hollow panels of different cross section and connected into a heat recovery cycle. Each prototype has been tested at 4 levels of outdoor air volume flow (from 125 to 400 m3·h−1) and 4 levels of dry bulb temperature (from 25 to 40 °C). For each of the 16 different operating conditions the exergy destructed by each prototype has been calculated. Results show that the higher the dry bulb temperature at the primary air inlet, the higher the exergy destruction and the exergy losses. The exergy destruction increases when the wet bulb depression temperature of the secondary air inlet decreases, leading to more inefficient configurations. The value of the exergetic efficiency is in the order of 2–12 %. The optimum combination of operating conditions at any inlet temperature of the primary air can be proposed as: 300 m3h−1 and 200 m3h−1. for the wide and narrow plates prototype, respectively.

Located in Baoding, northern China’s Hebei Province, the Daqing River Basin faces a nonnegligible problem: the prevention and control of ice damage in the South-to-North Water Diversion Project (SNWDP) during the ice period. This paper sorts out the observation data on the ice conditions in river sections of the Daqing River Basin in winter, 1994–1997, and calculates the roughness of the water transmission sections, through mathematical calculation and inverse computation. On this basis, the authors analyzed the influence of ice caps on the flow capacity of river channel, and discussed the effects of water level variation on ice cap stability. The results show that, during the ice period, the ice caps in the upstream of the water transmission channel in the river basin are rougher than those in the downstream. In the same river section, the ice caps are rougher in the initial phase than the late phase. At the same water level, the flow capacity of different sections reduces by 40–61% under ice caps. For the entire river channel, the ice caps lower the flow capacity by 40–52%. The water level variation has a huge influence of ice cap stability. During the ice period, the flow should be maintained stable to transmit water under ice caps. This helps to stabilize water level, ensure the continuity and completeness of ice caps, and improve the water transmission efficiency in the ice period.

The demand of energy saving and loss mitigation in modern industry gives rise to drag reduction techniques such as micro groove/riblet ever since the last century. Plenty of studies are conducted under straight flow condition showing relevance between drag reduction and flow features. However, the same issue has not been studied adequately for rotational flows, which is typical in turbopumps. In this paper, two-dimensional numerical simulations of rotating disks are performed together with verification experiments to investigate drag reduction effect of micro riblet under rotational flow condition. The numerical results show that riblets with certain dimensions can lessen the resistant torque by a maximum of 8.46% and the drag reduction efficiency depends on rotational Reynolds number and riblet dimensions. Meanwhile, the distributions of static pressure and swirl velocity on surfaces are changed and near-wall turbulence intensity is tranquilized by riblets which are considered as the main reasons to the diminish of drag. Finally, the relevance of vortexes inside riblets to swirl wall shear stress and torque is demonstrated revealing that the configuration of riblets plays an important role in cutting resistance. The results of this paper can be a supplement for the investigation of micro groove/riblet drag reduction mechanism.

The chemical looping hydrogen production (CLHP) process is a new approach for hydrogen ( H 2 ) fuel production. The proposed process consists of three reactors which are air reactor (AR), fuel reactor (FR) and steam reactor (SR). In this study, the gas solid flow behaviour in a cold model of the proposed CLHP process was simulated using computational fluid dynamics (CFD) with kinetic theory of granular flow. The effect of drag coefficient models on the pressure profile of each reactor was investigated and the results from the modified Syamlal–O’Brien drag model agreed well with the experimental data. The model was further used to investigate effects of the operating parameters on the hydrodynamics profiles of each reactor. The solid flux increased with the increasing of inlet velocity of AR and FR but decreased with the increasing of the inlet velocity of SR. At the same time, the solid flux increased with the increasing of the solid inventory.

Nanofluids are expected to be utilized in more efficient based processes. Such nanofluids are employed in cancer therapy, computer electronics, food packaging, and physical sciences, etc. The study focuses on the influence of bioconvection Carreau nanoliquid transport passing via a moving surface. Furthermore, the major properties of the Lorentz force and the magnetic field in Carreau nanoliquid transport are explored. The system of governing PDEs is turned into ODEs by using the appropriate transformation method and then solved by employing the bvp4c technique in computational MATLAB software (Lobatto IIIa formula). The contribution of several key numbers against the velocity profile, concentration profile, temperature profile, and microorganisms’ profile are monitored, and the findings are represented by graphs and numerical data.

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2021-12-24, PA2210037000

This paper presents the flow fields and aerodynamic loading of a two bladed H‐type vertical axis wind turbine with active variable pitch for load and circulation control. Particle Image Velocimetry is used to capture flow fields at six azimuthal positions of the blades during operation, three upwind and three downwind. Flow phenomena such as dynamic stall and tower shadow are captured in the flow fields. The phase‐averaged velocity fields and their time and spatial derivatives are used to calculate the normal and tangential loading at each position for each pitching configuration using the Noca formulation of the flux equations. The results show the effect of load shifting from the upwind to downwind region of the actuator using pitch and the effects of dynamic stall on the blades. The results also provide an unique database for model validation.

Geological disasters such as slope failure and landslides can cause loss of life and property. Therefore, reproducing their evolution process is of great importance for risk assessment and mitigation. The recently developed SIMSAND critical state sand model combined with the smoothed particle hydrodynamics (SPH) method is adopted in this work to study slope failure under large deformations. To illustrate the efficiency and accuracy of the SIMSAND-SPH approach, a series of slope collapse studies using the discrete element method (DEM) considering various particle shapes (i.e. spherical, tetrahedral and elongated) is adopted as benchmarks. The parameters of the SIMSAND model are calibrated using DEM triaxial tests. In comparison to the DEM simulations, the runout distance and final slope height are well characterized with the SIMSAND-SPH approach with less computational cost. All comparisons show that the SIMSAND-SPH approach is highly efficient and accurate, which can be an alternative numerical tool to simulate real scale granular flow.

Structured grids have drawbacks such as cell distortion and artefacts leading to numerical accuracy reduction during simulations. Spatial support size had proven its importance in various estimation, and this is where unstructured grid comes into action. Performing geostatistical simulation on unstructured grid requires accounting of support size effect. In this article, two methods have been used for accounting the support size effect, one is the classical fine-scale simulation approach and the other approach is using Discrete Gaussian Model (DGM). Each method is applied to generate simulated Digital Elevation Model (DEM) (as used in this study) and the resultant DEMs are studied to understand the effect of spatial support size on surface flow estimation of water. It was observed that due to regularisation in the data of unstructured grid the flow velocity and water surface elevation of the unstructured DEM gave a similar behaviour than the structured DEM. The minimum RMSE for water surface elevation is 0.83 m for unstructured DEM while the minimum RMSE for flow discharge is 0.38 m3/s. The maximum coefficient of determination of flow channel velocity and water surface elevation is 0.709 and 0.86 respectively. The results suggested that the unstructured DEM generated using DGM approach shows a high correlation to reference DEM used in this study than the simulated structured DEM. The surface flow output it was inferred the flow variation in both structured and unstructured DEM is affected not only by the vertical resolution of DEM but also by the horizontal resolution.

The novel autonomous rolling performance is realized by the pair of pectoral fins of a three-dimensional(3-D) bionic dolphin in this paper numerically. 3-D Navier-Stokes equations are employed to simulate the viscous fluid around the bionic dolphin. The effect of self-rolling manoeuvrability is explored using the dynamic mesh technology and user-defined function (UDF). By varying the parameter ratios, the interaction of flexible pectoral fins is divided into two motion modes, amplitude differential and frequency differential mode. As the primary driving source, the differential motion of a pair of pectoral fins can effectively provide the rolling torque, and the trajectory of the entire rolling process is approximately the clockwise spiral. The results demonstrate that the rolling angular velocity and driving torque in the steady state can be improved by increasing parameter ratios, and the rolling efficiency can reach the maximum under the optimal parameter ratio. Meanwhile, different parameter ratios do not affect the rolling radius of the self-rolling dolphin. The evolution process around the pair of pectoral fins is shown by the flow structures in self-rolling swimming, reasonably revealing that self-rolling locomotion is produced by the pressure and wake vortices surrounding the pair of pectoral fins, and the wake structure depends primarily on the variation of parameter ratio. It properly turns out that the application of the pair of pectoral fins can realize the self-rolling performance through parameter differential modes.

In this study, a free energy model of the Lattice Boltzmann Method (LBM) is performed to simulate the motion, deformation, and decomposition of a droplet in the presence of electrohydrodynamic flow in porous media. To simulate the multi-phase flow in the presence of dielectric current by using the LBM, three distribution functions are used. To implement the free energy mode of HCZ, two equilibrium distribution functions are considered, one for solving the Navier-Stokes equation and the other for solving the Cahn-Hillard equation. Initially, the ability of the code to apply surface tension is tested by using the Laplace law and the droplet release test. Results show that there is a linear relation is between surface tension and κ which is a parameter in the HCZ model. The results show that the present numerical program is capable of modeling the regulated surface tension force as well. Then, the Rayleigh–Taylor instability simulation is used to evaluate the code's ability to apply volume forces. Also, the obtained results of the written numerical program are in good agreement with the numerical results of other valid references. Obtained results show that the difference between droplet deformation measured by numerical method and Taylor function is less than 2%. After modeling the droplet motions to investigate the droplet deformation, two electric fields are inserted into the droplet with reverse directions of each other. Then, by various tests, it is shown that at a given potential difference the droplet breaks down after much deformation and is divided into smaller droplets. The decomposition of droplets in a pre-mixed emulsion is a common technique to produce the monodisperse droplets. The presence of monodisperse droplets in an emulsion improves the physical properties of polymer from the science expert's perspective. The results of this study are used to improve the quality of polymer components.

This paper presents a numerical investigation of two-phase natural circulation flows established when external reactor vessel cooling is applied to a severe accident of the APR1400 reactor for the in-vessel retention of the core melt. The coolability limit due to external reactor vessel cooling is associated with the natural circulation flow rate around the lower head of the reactor vessel. For an elaborate prediction of the natural circulation flow rate using a thermal-hydraulic system code, MARS-KS1.5, a three-dimensional computational fluid dynamics (CFD) simulation is conducted to estimate the flow rate and pressure distribution of a liquid-state coolant at the brink of significant void generation. The CFD calculation results are used to determine the loss coefficient at major flow junctions, where substantial pressure losses are expected, in the nodalization scheme of the MARS-KS code such that the single-phase flow rate is the same as that predicted via CFD simulations. Subsequently, the MARS-KS analysis is performed for the two-phase natural circulation regime, and the transient behavior of the main thermal-hydraulic variables is investigated.

In the geological repository of radioactive nuclear waste, anaerobic corrosion can generate hydrogen, and may conservatively lead to the production of hydrogen-air layer. The accumulated hydrogen may cause a hazardous flame propagation resulting from any potential ignition sources. This study numerically investigates the processes of ignition and flame propagation in the layered mixture. Simple geometry was chosen to represent the geological repository, and reactive flow simulations were performed with different ignition power, energy, and locations. The simulation results revealed the effects of power and energy of ignition source, which were also analyzed theoretically. The mechanism of layered flame propagation was suggested, which includes three stages: propagation into the hydrogen area, downward propagation due to the product gas, and horizontal propagation along the top wall. To investigate the effect of the ignition source location, simulations with eight different positions were performed, and the boundary of hazardous ignition area was identified. The simulation results were also explained through scaling analysis. This study evaluates the potential risk of the accumulated hydrogen in geological repository, and illustrates the layered flame propagation in related ignition scenarios.

The Shell-and-tube type heat exchangers have long been widely used in many fields of industry. These types of heat exchangers are generally easy to design, manufacturing and maintenance, but require relatively large spaces to install. Therefore the optimization of such heat exchangers from thermal and economical points of view is of particular interest. In this article, an optimization procedure based on the minimum total cost (initial investment plus operational costs) has been applied. Then the flow analysis of the optimized heat exchanger has been carried out to reveal possible flow field and temperature distribution inside the equipment using computational fluid dynamics. The experimental results were compared with computational fluid dynamics analyses results. It has been concluded that the baffles play an important role in the development of the shell side flow field. This prompted us to investigate new baffle geometries without compromising from the overall thermal performance. It has been found that the heat exchanger with the new baffle design gives rise to considerably lower pressure drops in the shell side, which in turn reducing operating cost. The new baffle design is particularly well suited for shell-and-tube heat exchangers, where a viscous fluid flows through shell side with/out phase change.

The most popular mechanism of the critical heat flux (CHF) triggering is dry-out through bubble packing, which prevents the liquid inflow onto the heater. It is common knowledge that the generated upward bubble flow on the heater easily blocks a small flow path for the downward liquid inflow during pool boiling. This blocked hydrodynamic liquid flow path normally leads to dry-out and CHF on the heated surface. In the present study, we design a unique test section to assess the effect of a small flow path and the wall through the installation of a cylindrical wall close to the heater. We measure the CHF for various diameters and heights of the cylindrical wall and notice an interesting trend in the plots. Contrary to common knowledge, we find the CHF enhancement in a narrowed hydrodynamic flow path between the heater and cylindrical wall compared to the bare CHF performance. From this result, the enhancement mechanism is suggested based on the accelerated inflow bulk liquid and shortening period between growing and departing bubble by the confined wall effect. This is the first study to report on the relationship between the CHF and the diameter and height of the cylindrical wall.

In this study, a high-voltage heater system with a size of 310 mm × 210 mm × 60 mm has been numerically studied and experimentally verified to explore the influence of the cavity structure on the flow and heat transfer performance. the response surface model and analysis of variance are used to determine the influence of the length of the mainstream area of the inlet (Lin), the length of the mainstream area of the outlet (Lout), the length of the parallel flow channel (Lch) and the single channel width (W) on the flow heat transfer, and ultimately find the best structural plan. The results show that the structural parameters of the parallel flow channel are significantly more important than those of the mainstream area, with the width and length of the parallel single channel being the primary and secondary structural parameters, respectively. The optimization scheme obtained by the NGSA-II algorithm can simultaneously meet the requirements of heat transfer and flow uniformity. Specifically, compared with the original model, the flow distribution uniformity coefficient (S) and the inlet/outlet pressure drop (Ptotal) decreased by 53.49 and 19.52%, respectively, while the average heat transfer coefficient increased by 28.05%.

The evaporation demands upon a rock or soil surface can exceed the ability of the profile to bring sufficient amount of liquid water. A dry surface layer arises in the porous medium that enables just water vapor flow to the surface. The interface between the dry and wet parts of the profile is known as the evaporation front. The paper gives the exact definition of the evaporation front and studies its motion. A set of differential equations governing the front motion in space is formulated. Making use of a set of measured and chosen values, a problem is formulated that illustrates the obtained theory. The problem is solved numerically and the results are presented and discussed.

A bearing capacity evaluation for the surface strip foundation on a working platform modelled on a two-layered substrate is considered in the study. The upper layer is assumed as man-made and well-controlled and thus non-variable. The lower layer modelling natural cohesive soil is subjected to spatial variability of undrained shear strength. The random failure mechanism method (RFMM) is used to evaluate the bearing capacity. This approach employs a kinematic assessment of the critical load and incorporates the averaging of three-dimensional (3D) random field along dissipation surfaces that result from the failure geometry. A novel version of the approach considering an additional linear trend of undrained shear strength in the spatially variable layer is proposed. The high efficiency of the RFMM algorithm is preserved. The influences of foundation length, trend slope in the spatially variable layer, fluctuation scales, and thickness of the homogenous sand layer on the resulting bearing capacity evaluations are analysed. Moreover, for selected cases, verification of the RFMM based assessment obtained using random finite difference method (RFDM) based on 3D analysis is provided. Two types of analyses are performed using RFDM based on associated and non-associated flow rules. For associated flow rule which corresponds to RFDM, the RFMM is conservative and efficient and thus it seems preferable. However, if RFDM employs non-associated flow rule (much lower dilation angle for sand layer), the efficient RFMM is no longer conservative. For this situation, a combined approach that improves the efficiency of the numerical method is suggested.

An analysis related to the transport of nanofluid that is confined in a channel between two orthogonal permeable walls will be investigated with the help of two numerical techniques. With the aid of the reasonable similarity changeover; the said model will be shaped into the desired non-linear equation whose behavior will be explained analytically as well as graphically where the functioning of three disparate variables such as magnetic parameter, permeable Reynold number, and channel permeable ratio will be explained precisely. The said model has been controlled by the homotopy analysis method (HAM) and then, compared through an efficient numerical method named shooting method (ShM). The profiles show that increases in the magnetic parameter decline the nanofluid flow velocity, whereas magnitude-wise raise is shown in each axial velocity profile. The radial profile raises while getting variation in wall expansion parameter from negative to positive. For the entire domain, the rate of change in velocity description enhances at the center while reduces at the surfaces. And the outcomes disclose that the wall permeable ratio has a significant impact on the solutions. Since the zero value of wall ratio refers to the particular type that Terrill has discussed.

In this analysis, the modified nanofluid flow at a nonlinear stretching Riga plate is considered. The impacts of variable viscosity are considered. The modified nanofluid is the extended version of the hybrid nanofluid. This is the mixture of three nanoparticle and base fluid. The heat transfer rate depends on the thermal conductivity because heat transfer rate and thermal conductivity directly proportion which provided in the literature. The developed model solved through numerical technique. The basic achievement of this analysis is to explore about the heat transfer improvement that gains higher as compared to Hybrid nanofluid and nanofluid, (see Fig. 1 ). Heat transfer properties and modified nanofluid show exciting behavior which deserve further study on the modified nanofluid. The ϕ 3 disperse the energy in the shape of heat than the mixture of more nanoparticles may more exert energy in the form of heat.

In this article, the authors present a test of wake steering at a commercial wind farm. A single fixed yaw offset, rather than an optimized offset schedule, is alternately applied to an upstream wind turbine and the effect on downstream turbines is analyzed. This experimental design allows for comparison with engineering wake models independent of the controller's ability to track a varying offset and correctly measure wind direction. Additionally, by applying the same offset in beneficial and detrimental conditions, we are able to collect important data for assessing second-order wake model predictions. Results of the article from collected data show good agreement with the FLOw Redirection and Induction in Steady State (FLORIS) engineering model and offer support for the asymmetry of wake steering predicted by newer models, such as the Gauss-curl hybrid model.

The main aim of the research presented in the work was to assess the usefulness of the dynamic SWMM (stormwater management model) and the conceptual SBUH (Santa Barbara Urban Hydrograph) model for simulating and predicting flow hydrographs in a small urbanized catchment under conditions of controlled (using valves) outflow from stormwater retention tanks in response to rainfall events. Most of the analyzed catchment of the Służewiecki Stream consists of the area beneath F. Chopin International Airport in Warsaw. A further aim of the study was the development of method for indicating the concentration time for a given rainfall–runoff event, where the influence of delaying the outflow of stormwater from the catchment as a result of its retention in tanks on the value of this parameter will be accounted for. The values of the median of absolute errors, obtained in a simulation using the SWMM in relation to peak flows and hydrograph volumes for the analyzed events, were 15.4 and 18.4%, respectively. The adequate values of simulation errors, obtained in the SBUH model using concentration times determined according to the developed method, were 11.4 and 15.4%. Satisfactory results of simulations were received using both models. HIGHLIGHTS Development of a method for indicating the concentration time for a given rainfall–runoff event in an urbanized catchment.; Application of the dynamic SWMM and conceptual Santa Barbara Urban Hydrograph model for simulating flow hydrographs in a catchment under conditions of controlled (using valves) outflow from stormwater retention tanks.; Assessment of the usefulness of models belonging to different classes for simulating flow hydrographs.

Acid fracturing is an important means of reservoir stimulation, whose purpose is to form an incompletely closed acid-etched fracture as the flow channel for oil and gas during production. The length and conductivity of acid-etched fractures can be used to evaluate acid fracturing and directly impact production. To study their influence on the stimulation effect and final production, an acid fracturing coupling model including a fracture propagation model coupled with reservoir flow and temperature field models is established for the first time in this study based on an embedded discrete fracture model (EDFM), which can realize the coupling of fracture propagation and reservoir flow and simplify the solution of fracture and reservoir temperatures. The simulation results of the acid fracturing coupling model are introduced into the productivity model, which is also based on the EDFM to analyze and evaluate well productivity. The results show that: (1) the EDFM can easily couple fracture propagation and reservoir flow and can be used to rapidly solve the temperature fields in the fracture and reservoir successfully for the first time. (2) Reservoir flow impacts the propagation of fractures by increasing or decreasing the leak-off velocity of the working fluid. (3) Temperature diffusion is much weaker than pressure diffusion during acid fracturing and is limited near the acid fracture. The reaction between the acid and rock increases the local temperature around the acid fracture, and may even exceed the initial formation temperature. (4) Raising the injection rate reasonably enhances H+ diffusion, increases the effective length of acid-etched fractures, enlarges the drainage area of oil and gas, and benefits long-term well production.

Experiments were performed to examine the variations in flow turbulence with respect to sand and gravel bed channel. The 3D instantaneous velocity of water is measured by acoustic doppler velocimeter (ADV) at the test section, which will provide an important data related to the flow turbulence. The parameters of turbulence measured that the vertical profiles of longitudinal velocity in flows with a sand bed channel at the vicinity of the bed surface are higher by 2–6% than flow subjected to gravel bed channel, while away from the boundary surface, it decreases by 5–10%. The variations of Reynolds shear stress increase by 35–50% with gravel bed channel, indicating higher exchange of flow energy towards the boundary and vice versa. The higher value is obtained for shear velocities by 58.5% and the von Karman's constant with gravel bed channel. The gravel bed channel influenced the turbulence intensities with higher magnitude in the streamwise and vertical direction. The present study also analysed the flow anisotropy, correlations coefficient and turbulence diffusivity and compared the results. The outcomes of the current work are beneficial for civil and hydraulic engineers, since the data of turbulence will advance the management of bed materials present in the river. HIGHLIGHTS Water velocity is higher at the near bed in a sand bed channel.; A gravel bed channel increases the velocity fluctuations.; Flow momentum exchange is higher in a gravel bed channel.; Riverbeds are usually composed of sand and gravel, therefore analyzing the turbulent characteristics of flow is important.; There are benefits for the river engineer since the turbulence governs the morphological changes in the riverbeds.

The centerline streamwise and cross-sectional (x/Dh = 0.425) turbulence characteristics of a 2D planar space-filling square-fractal-grid (SFG) composed of self-similar patterns superimposed at multiple length-scales is experimentally unveiled via piezoelectric thin-film flapping velocimetry (PTFV). The fluid–structure-interaction between a flexible piezoelectric thin-film and SFG-generated turbulent flow at ReDh = 4.1 × 104 is investigated by analysis of the thin-film’s mechanical response. Measurements of the thin-film-tip deflection δ and induced voltage V demonstrate increasing flow fluctuation strength in the turbulence generation region, followed by rapid decay further downstream of the SFG. Interestingly, SFG-induced turbulence enables the generation of maximum centerline thin-film’s response (Vrms, δrms) and millinewton turbulence-forcing (turbulence-induced excitation force acting on the thin-film) Frms which are respectively, 7× and 2× larger than the classical square-regular-grid of similar blockage ratio. The low frequency, large-scale energy-containing eddies at SFG’s central opening plays a critical role in driving the thin-film vibration. Most importantly, the SFG-generated turbulence at (y/T = 0.106, z/T = 0.125) away from the centerline allows equivalent mechanical characteristics of turbulence generation and decay, with peak of 1.9× nearer from grid. In short, PTFV provides a unique expression of the SFG-generated turbulence, of which, the equivalent turbulence length-scale and induced-forcing deduced could aid in deciphering the flow dynamics for effective turbulence management.

Terrestrial groundwater discharge (TGWD) can be an important pathway for pollutants into coastal water bodies. Thus, a reliable way to quantify it is essential for efficient coastal management practices. This study evaluated the feasibility of using constant-density models for estimating TGWD amounts into the Indian River Lagoon, which is a variable-density estuarine environment. Constant-density models were developed using MODFLOW, while variable-density models were developed using SEAWAT. The numerical models were calibrated to match the field measured head data under the lagoon. The amounts of TGWD into the IRL and hydraulic head distributions calculated by the two codes were compared over eight pairs of numerical experiments. Two of those numerical experiments used the calibrated model and field measured conditions, while the rest of them used modified versions of the calibrated models, including variable anisotropy ratio k, variable lagoon salinity LS, and increased water table elevation by 5%. The results showed that the constant-density model is fairly accurate in estimating TGWD and head distributions at the calibrated k in the range of 1000-20,000 with an error not exceeding 9.4% under the actual measured field conditions. Even when LS was assumed to increase to ocean salinity value of 1.0, a case that rarely occurs in IRL, the calibrated constant-density model’s accuracy was not affected substantially. However, the constant-density model failed to represent the physics of the variable-density environment at k values lower than 1000, where the error exceeded 129%. Generally, the accuracy of the constant-density model was found to increase substantially at lower LS and higher water table elevations.

To evaluate the long-term performance of bioretention cell (BRC), a study was undertaken to assess the flow distribution and conductivity. Despite initial conductivity of the original medium being the common predictor of hydraulic performance, most of the BRCs are affected by conductivity variations during actual operation. This happen due to the fact that microbial behavior plays an important role in the conductivity variations. This linkage may occur when bacteria as inert colloids transports between particles and biodegrades dissolved pollutants, either promoting or retarding flow distribution and conductivity in BRC. Flow distribution was determined by numerical simulation and tracer test, and the correlation between conductivity and flow distribution was revealed by conductivity experiment coupled with flow distribution analysis. Results revealed a non-uniform flow distribution in BRC, and seepage flow in submerged zone was virtually impossible push flow. Conductivity had an inversely proportional relationship with hydraulic efficiency where hydraulic efficiency reached the highest value (0.297) under a low hydraulic conductivity (0.000107 m/s, approximately K/Kini = 0.79). Primary cause of hydraulic capacity reduction was the initial permeability decrease due to medium structure changes. Results revealed a sharp upward trend followed by a slight decrease, and then, stabilized to a stable infiltration stage. Permeation process of sewage influent was similar to the one of potable water where the permeability reduced to 0.000102 m/s after 450 h and declined continuously. Thus, it is clear that flow distribution and conductivity in bioretention must be estimated more accurately on a microscopic scale.

In this new-fangled research, the mixed convective stagnation point flow of a hybrid nanofluid over a yawed cylinder with radiation impact is considered. In reality, the perception of mixed convection in the study of yawed cylinder rises in heat exchangers. To explore the heat diffusion through the system of mixed convection, the mathematical problem is formed in the form of partial differential equations which are coupled and nonlinear. A solution technique is applied and described for indulgencing non-similar thermal boundary layers. The non-similar terms involving in the transformed equations are held without approximations. The non-similar equations are solved numerically using the bvp4c technique. The exploration divulges numerous significant results involving yaw angle, hybrid nanoparticle volume fraction, mixed convection, radiation, and non-similarity phenomena. The impact of the yaw angle in enhancing the velocity of the hybrid nanofluid in the span-wise and chord-wise directions in the aiding buoyancy flow and decelerating in the opposing flow, while the contrary behavior is noticed for the dimensionless temperature profile. Also, the hybrid nanoparticles reduce the velocity in both directions in case of assisting as well as opposing flow, whereas the dimensionless temperature augments.

The effect of width opening downstream of chute structure on the depth and the dimensions of downstream scour hole was investigated using a physical model in the presence of two different block geometries, including a USBR block and a lattice block installed on chute. For this purpose, five chute structures with baffled blocks were designed and constructed, including three models with a divergence ratio of 1.45, 1.75, and 2.45, including a USBR block and 2 models without divergence with a divergence ratio of 1, including USBR and lattice blocks. The results increase the chute widening ratio from 1 to 2.45 reduced the mean and maximum depths and the mean and maximum lengths of scour pit, while enhancing the flow energy dissipation along the chute. Besides, using perforated piers increased the length of scour pit, while reducing its depth and the relative flow energy dissipation.

After a year of the heat exchanger operation in overload conditions, a number of cracks on the tube connections to the tubesheet have been observed. To explain the stress concentration and crack initiation, a finite element analysis is performed. A three-dimensional model is constructed and analyzed. To calculate more precisely the state of stress in the most loaded regions, a submodel is created. The maximum stress exceeds the allowable stress, and according to the standards, it can lead to ratcheting. To reduce stress concentration, all tubes should be shortened and corrugated tubes are installed in the high-temperature region from the side of the burner. A finite element model of the modified heat exchanger and a submodel are created. In the modified heat exchanger, ratcheting should not occur according to the applied standards. During the operation of the modified heat exchanger, there are no further problems with cracking.

As the first barrier of wellbore integrity, tubing string is an important guarantee for safety production. However, with the rapid consumption of oil and gas, the mechanical environment in wellbore is becoming more and more harsh, which poses a challenge to the safe service of tubing string. In order to systematically study the erosion of buckling tubing string in high temperature and high pressure (HTHP) ultra-deep wells, the researches on buckling deformation and erosion of tubing string are carried out gradually in this paper. There are three steps in the research process: (a) The tests including metallographic, mechanical properties and hardness of studied tubing material are carried out, and the test results are the basis of the next numerical simulation; (b) the finite element model (FEM) of whole section tubing sting-packer-casing is established to study the buckling deformation of tubing string due to the comprehensive effect including piston effect, ballooning effect, temperature effect, friction effect and buckling effect; (c) according to the buckling flow passage, FEM of tubing erosion is established based on erosion mode, fluid–solid coupling and impact of sand on each other. Finally, the erosion rule and failure region on tubing are obtained. The researches presented in this paper can provide reference and guidance for predicting erosion and protecting the tubing string.

The performance of high-temperature polybenzimidazole (PBI) proton exchange membrane fuel cells (HT-PEMFCs) doped with phosphoric acid is strongly influenced by the configuration of its flow channel. In this research, genetic algorithm (GA) is adopted to optimize original three-dimensional simulation model by obtaining the optimal design of the channel configuration. Set the widths of top and bottom edges of the anode/cathode flow channels as independent variables with constrained range to optimize HT-PEMFC performance. The ratio of the pressure drop loss to the output power of the HT- PEMFC is set as the objective function. The results show that the widths of the top and bottom edges are 0.513 mm 0.635 mm at the anode side, and 0.752 mm and 1.159 mm at the cathode side, respectively. The shape of the cross-sectional of the flow channel is trapezoidal, which can achieve the best performance. In the anode side, the narrow contact surface between the flow channel and the GDL can increase the diffusion rate of the hydrogen. For cathode, the larger contact surface formed by the flow channel and the GDL can provide more gas to carry out the electrochemical reaction. The pressure drop loss and output power of the optimal model are 1.7% and 6.5% greater than those of the original model at 0.4 V, respectively. The results can contribute to improve the design and operation of HT-PEMFCs in the future.

Looking for an optimal flow shape for culture growth in vortex bioreactors, an intriguing and impressive structure has been observed that mimics the strong swirling flows in the atmosphere (tornado) and ocean (waterspout). To better understand the flow nature and topology, this experimental study explores the development of vortex breakdown (VB) in a lab-scale swirling flow of two immiscible fluids filling a vertical cylindrical container. The rotating bottom disk drives the circulation of both fluids while the sidewall is stationary. The container can be either sealed with the still top disk (SC) or open (OC). As the rotation strength (Re) increases, a new circulation cell occurs in each fluid—the dual VB. In case SC, VB first emerges in the lower fluid at Re = 475 and then in the upper fluid at Re = 746. In case OC, VB first emerges in the upper fluid at Re = 524 and then in the lower fluid at Re = 538. The flow remains steady and axisymmetric with the interface and the free surface being just slightly deformed in the studied range of Re. Such two-VB swirling flows can provide efficient mixing in aerial or two-fluid bioreactors.

For many applications, it would be extremely useful to have insights into river flows at timescales of a few weeks to months ahead. However, seasonal predictions of this type are necessarily probabilistic which raises challenges both in generating forecasts and their interpretation. Despite this, an increasing number of studies have shown promising results and this is an active area for research. In this paper, we discuss insights gained from previous studies using a novel combined water balance and data-driven approach for two of Africa's largest lakes, Lake Victoria and Lake Malawi. Factors which increased predictability included the unusually long hydrological response times and statistically significant links to ocean-atmosphere processes such as the Indian Ocean Dipole. Other lessons learned included the benefits of data assimilation and the need for care in the choice of performance metrics.

Parabolic trough collector (PTC) is the most cost-effective and mature concentrated solar power (CSP) technology for solar thermal utilization. However, the highly concentrated solar irradiation on the bottom of the absorber tube causes high local temperature, thermal stress and deformation, further leading to damage and performance degradation of PTC. In order to alleviate the above problem, a novel parabolic trough receiver (PTR) with ribbed absorber tube is proposed to improve the thermo-mechanical performance of PTC Moreover, the multi-objective optimization is employed to determine the optimal parameter combinations (slant angle ( β ), size (e), pitch (p), and number of the ribs (N)) of ribbed absorber tube coupled with 3D numerical simulation and the genetic algorithm (GA). Based on the TOPSIS method and performance evaluation criteria (PEC) value, the ribbed absorber tube with the optimal geometric parameters of β = 15 ° , N = 6 , e = 4 . 5 mm and p = 20 mm is selected in the Pareto Front as the suggested optimal design. Furthermore, the performance of the PTRs at different inlet temperature of the fluid ( T i n = 400 –600K), direct normal irradiance (DNI=300–1000 W/m2) and mass flow rate (M=0.62–3.72kg/s) are evaluated. It is found that the ribbed absorber tube can effectively disturb the fluid near the boundary and induce longitudinal vortexes flow, which results in significant improvement in heat transfer between fluid and absorber tube, thereby enhancing the performance of the PTC. Compared to the plain tube, the heat transfer and flow resistance of the optimal ribbed absorber are enhanced by 57%–225% and 222%–630%, and the heat loss is lessened by up to 79.3%, resulting in 2.3% and 2.2% improvement in the heat collecting efficiency and overall efficiency. The findings in this paper may provide practical guidelines for developing efficient PTC.

Wake steering is a wind farm control strategy in which upstream wind turbines are misaligned with the wind to redirect their wakes away from downstream turbines, thereby increasing the net wind plant power production and reducing fatigue loads generated by wake turbulence. In this paper, we present results from a wake-steering experiment at a commercial wind plant involving two wind turbines spaced 3.7 rotor diameters apart. During the 3-month experiment period, we estimate that wake steering reduced wake losses by 5.6 % for the wind direction sector investigated. After applying a long-term correction based on the site wind rose, the reduction in wake losses increases to 9.3 %. As a function of wind speed, we find large energy improvements near cut-in wind speed, where wake steering can prevent the downstream wind turbine from shutting down. Yet for wind speeds between 6–8 m/s, we observe little change in performance with wake steering. However, wake steering was found to improve energy production significantly for below-rated wind speeds from 8–12 m/s. By measuring the relationship between yaw misalignment and power production using a nacelle lidar, we attribute much of the improvement in wake-steering performance at higher wind speeds to a significant reduction in the power loss of the upstream turbine as wind speed increases. Additionally, we find higher wind direction variability at lower wind speeds, which contributes to poor performance in the 6–8 m/s wind speed bin because of slow yaw controller dynamics. Further, we compare the measured performance of wake steering to predictions using the FLORIS (FLOw Redirection and Induction in Steady State) wind farm control tool coupled with a wind direction variability model. Although the achieved yaw offsets at the upstream wind turbine fall short of the intended yaw offsets, we find that they are predicted well by the wind direction variability model. When incorporating the expected yaw offsets, estimates of the energy improvement from wake steering using FLORIS closely match the experimental results.

Pseudo threshold pressure gradient (PTPG) is one of the main factors affecting the oil recovery of heterogeneous low-permeability and tight reservoirs. When the pressure gradient between the supply boundary and the bottom hole is less than PTPG, the crude oil in the formation cannot flow. In order to accurately measure the relationship between PTPG and permeability, a novel experimental device has been designed and a series of core flooding experiments using brine and oil have been carried out. The new experimental device eliminates the influence of rubber sleeve in core holder and core end-effect on the results, and greatly improves the accuracy of pressure measurement. The experimental results show the PTPG has a power function relationship with permeability, and has no obvious relationship with the viscosity of the fluid. Based on the equation for PTPG and permeability of crude oil and brine fitted by the experimental data, a new heterogeneous reservoir mathematical model considering PTPG were established. The influence of the coefficient of permeability variation, average permeability, and the production rate on oil recovery factor have been studied by this model. The results clearly show that the coefficient of permeability variation has the greatest influence on oil recovery factor, which represents inhomogeneity in low-permeability and tight reservoirs. Also, when the coefficient of permeability variation is less than a certain value (about 0.2 when average permeability is 1mD, in our model), there is only a slight decline in oil recovery factor, and when coefficient of permeability variation is larger than this value, the oil recovery factor decreases rapidly. The finding is consistent with oil field production and helpful to determine whether to take EOR(enhanced oil recovery) measures for a low-permeability heterogeneous reservoirs.

The present study proposed an optimized fractional-order model for a Proton Exchange Membrane Fuel Cells (PEMFC) to use in forecasting its behavior and examining unknown parameters affecting the cell efficiency. Here a new metaheuristic called the developed Water Strider Algorithm (dWSA) is suggested to define the unidentified variables of the considered PEMFC model. The idea is to optimal modeling of the parameters by minimizing the Sum of Squared Error (SSE) between the actual and the predicted terminal voltages of the PEMFC. To give a fair verification, a comparison of the results for the suggested model is established with the integer-based model and some other fractional-based optimized methods. Final results specified that incrementing of the H 2 flow made fractional models terminal voltage of the PEMFC stack to be changed slowly than the integer-order model. Consequently, more similar results to the actual operating characteristics are achieved for the PEMFC stack by the proposed method. Also, the results indicate that using the suggested model gives the optimum results compared with other fractional-based models to model the dynamic features of the PEMFC stack that is efficient to assess the association between the hydrogen flow and the terminal voltage.

Air leakage around the in-seam borehole leads to a poor quality of gas extracted, thus gas outburst danger is difficult to eliminate but also may cause other disasters, such as coal spontaneous combustion and gas explosion. Moreover, the low concentration gas discharged into the atmosphere always possesses an intense greenhouse effect. To investigate multiphase and multifield coupling problem of gas extraction, a dual medium coupling model was developed in this study to describe the gas–air mixture flow by considering the influences of matrix shrinkage and effective stress on coal permeability. And the coupling model was calculated by the 3D numerical simulation and presented an ideal matching result with the field data. Then, the key factors affecting the gas extraction quality were also investigated with the model. It was found that the gas concentration elevated with the increase in the sealing length and borehole diameter, and reduced with the augmentation of extraction negative pressure and coal permeability. Therefore, we developed an improved sealing technology, which can fully seal the various fractures around the borehole for improving gas extraction. The field test indicated that the gas concentration by this improved sealing technology was 1.91 times that of the traditional sealing method, and still maintained a relatively high extraction level in the subsequent extraction stage with a superior application effect. The results of this work can help in optimizing the borehole sealing technology for improving gas extraction quality, which is of great significance to CBM exploitation and utilization, reduce greenhouse gas emission and ensure safe mining.

The submersible pump is the only power component of the ultra-high voltage (UHV) transformer which plays a key role in the cooling effect of the transformer. Metal particles produced by erosion and wear of submersible pump blades and walls can pose a serious threat to the transformer. Therefore, it is necessary to analyze the wear law of submersible pumps. In this study, the particle erosion of the submersible pump for solid–liquid flow is investigated numerically. Results show that the main erosion area occurs on the upper edge of the blades, and as the size and concentration of metal particles increase, the average erosion rate of each component also increases. The erosion patterns of blades and volute show asymmetry under the same conditions, the average erosion rate of each blade is related to its initial position, and the most severely eroded area of the volute occurs when the curvature angle of the volute is about 120°. When the particle size reaches 350 μ m and the volume fraction is 0.4%, the average erosion rate of the blade reaches its peak. The outcome of this study can provide valuable reference data for the design of impurity monitoring of submersible pumps and proposing fault warning schemes.

In microfluidics, a well-known challenge is to obtain reproducible results, often constrained by unstable pressures or flow rates. Today, there are existing stabilisers made for low-pressure microfluidics or high-pressure macrofluidics, often consisting of passive membranes, which cannot stabilise long-term fluctuations. In this work, a novel stabilisation method that is able to handle high pressures in microfluidics is presented. It is based on upstream flow capacitance and thermal control of the fluid's viscosity through a PID controlled restrictor-chip. The stabiliser consists of a high-pressure-resistant microfluidic glass chip with integrated thin films, used for resistive heating. Thereby, the stabiliser has no moving parts. The quality of the stabilisation was evaluated with an ISCO pump, an HPLC pump, and a Harvard pump. The stability was greatly improved for all three pumps, with the ISCO reaching the highest relative precision of 0.035% and the best accuracy of 8.0 ppm. Poor accuracy of a pump was compensated for in the control algorithm, as it otherwise reduced the capacity to stabilise longer times. As the dead volume of the stabiliser was only 16 nL, it can be integrated into micro-total-analysis- or other lab-on-a-chip-systems. By this work, a new approach to improve the control of microfluidic systems has been achieved. De två första författarna delar förstaförfattarskapet.

In district heating (DH) systems, the time of use of energy is becoming more important. For example, the use of sustainable baseload units over peak units is favored. Also heat production units coupled to the electricity grid, such as cogeneration plants and heat pumps, can profit from fluctuating prices and balance the electricity network at the same time. In this context, DH utility companies can benefit from shifting thermal loads in time. In the H2020 TEMPO project, a case study is being conducted to shift thermal loads using the thermal flexibility of the DH network. The thermal storage capacity of the network is utilized by dynamically changing the supply temperature. The study consists of two experimental campaigns, designed to dynamically characterize the available storage capacity in the DH network. In these campaigns, the supply temperature in one of the TEMPO demo sites was increased/decreased several times per day. The flow rate, supply and return temperatures were measured at the heat source and at a large customer building. The analysis of the experimental results focused on two aspects: the propagation of flow temperatures through the network and the response of customer substations to supply temperature changes. The data and knowledge gathered in these test campaigns will be used to develop models for a model predictive controller (MPC) which will be tested in the next heating season.

In this study, the sizing of primary side components for preparation of domestic hot water are analysed, both qualitatively and based on measurements of domestic hot water demand in one multi-family building with 268 apartments. The collected data spans a period of 18 days during the end of 2020 and is collected in 15-min, 1-min, and 6-s intervals. An overview of the historic development for the design of domestic hot water flow in Sweden is also presented. There is a long-standing argument in Sweden, that the current district heating guidelines result in an overdesign of the flow for domestic hot water. The consequence of this is oversizing heat exchangers and valves in the substations. This study assesses, qualitatively, the issues related to overdesigned primary side valves for preparation of domestic hot water. A revised design for domestic hot water flow for the Swedish context is also conceptualised. The study suggests that an improved design flow for domestic hot water in multi-family buildings can be derived based on empirical measurements. The 15-min intervals are observed to tone down information of peaks to a degree where it is unsuitable to use as basis for a new design flow. The 1-min data does appear to preserve information to a degree where it can be used to assess a design flow when related to data with a 6-s interval. The 6-s data is expected to constitute a resolution that may be less available, and in this study, it constitutes a representation of the real domestic hot water demands. However, to find a fitted curve to empirical data, for the design flow based on number of apartments per multi-family building, the population of datasets needs to be increased.

This paper aimed to justify the performance of a non-oscillatory TPA-based model proposed by the authors for capturing transient mix flow in sewer systems consisting of a variety of pipe shapes. The model utilizes a first-order Godunov Finite volume numerical scheme in which a Harten–Lax–van Leer (HLL) Riemann solver was used for calculating the fluxes at the cells’ boundaries. The spurious numerical solution associated with the transient mix flow analysis is suppressed by enhancing the numerical viscosity of the scheme when the pipe pressurization is imminent. Due to the lack of experimental data for systems with pipe shapes other than circular and rectangular, a hypothetical pipe system for which analytical solutions exist was employed to verify the model performance. The results reveal that for all pipe shapes considered, the model provides oscillation-free solutions even at a high acoustic speed of 1400 m/s. It is also observed that the numerical results are in perfect agreement with the analytical solution. The obtained results conclude that the proposed model can be utilized to capture transient responses of sewer systems with any pipe shape.

Lahars are one of the greatest hazards at many volcanoes, including Volcán de Fuego (Guatemala). On 1 December 2018 at 8:00pm local Guatemala time (2:00:00 UTC), an hour-long lahar event was detected at Volcán de Fuego by two permanent seismo-acoustic stations along the Las Lajas channel on the southeast side. To establish the timing, duration, and speed of the lahar, infrasound array records were examined to identify both the source direction(s) and the correlated energy fluctuations at the two stations. Co-located seismic and acoustic signals were also examined, which indicated at least 5 distinct energy pulses within the lahar record. We infer that varying sediment load and/or changes in flow velocity is shown by clear fluctuations in the acoustic and seismic power recorded at one of the stations. This particular event studied with infrasound provides insight into how lahars occur around Volcán de Fuego.

A comprehensive experimental investigation of water cold plate with different flow configurations for electronic cooling was conducted. Serpentine, parallel and wavy channels cold plate were designed to study the hydrothermal performance of water cold plate for electronic servers cooling. Thermal resistance, pressure drop, Nusselt number, servers’ temperatures and performance evaluation criterion were measured, evaluated and compared to evaluate the hydrothermal performance of the different configurations. The results showed that the serpentine channels cold plate has a better thermal performance than both parallel and wavy channels cold plate. The serpentine channels cold plate yields a lower thermal resistance by (6.02–10.5%), (2.4–8.7%) and a higher average Nusselt number by (7.9–13.9%), (6.3–13.7%) compared to parallel and wavy channels cold plate, respectively. Also, the results indicated that the serpentine channels cold plate has a higher pressure drop and pumping power compared to parallel and wavy channels cold plates. Similarly, the results showed that the wavy channel has better thermal performance than parallel channels due to the larger flow path and the rotational flow occurred. The I-Type inlet and outlet configuration used in the wavy channel cold plate provide a lower pressure drop compared to parallel channels however the large flow path. The performance evaluation criterion showed that the wavy channels cold plate has a higher performance evaluation criterion than serpentine channels due to its lower pressure drop.

In the present research, a novel mathematical model for the motion of cilia using non-linear rheological fluid in a symmetric channel is developed. The strength of analytical perturbation technique is employed for the solution of proposed physical process using mectachoronal rhythm based on Cilia induced flow for pseudo plastic nano fluid model by considering the low Reynolds number and long wave length approximation phenomena. The role of ciliary motion for the fluid transport in various animals is explained. Analytical expressions are gathered for stream function, concentration, temperature profiles, axial velocity, and pressure gradient. Whereas, transverse velocity, pressure rise per wave length, and frictional force on the wall of the tubule are investigated with aid of numerical computations and their outcomes are demonstrated graphically. A comprehensive analysis for comparison of Perturb and numerical solution is done. This analysis validates the analytical solution.