Showing papers in "Heat Transfer - Japanese Research in 2022"
TL;DR: In this article , a two-dimensional (2D) mathematical model is developed based on a homogeneous model for magnetohydrodynamics (MHD) nanofluid in an innovative porous, circleshaped enclosure incorporating a Cassini oval cavity using the Darcy law.
Abstract: This paper reports our study on the flow characteristics and heat transfer performance of magnetohydrodynamics (MHD) nanofluid in an innovative porous, circle‐shaped enclosure incorporating a Cassini oval cavity using the Darcy law. The MHD nanofluid considered in this study is Al2O3–H2O. A two‐dimensional (2D) mathematical model is developed based on a homogeneous model. The formulation of the vorticity stream function is then used to obtain coupled equations. Finally, the coupled partial differential equations are solved numerically using the finite element method. Model predictions are then compared against results from the previously published study to verify the accuracy and validity of the developed model, and a good agreement is achieved. Figures demonstrate the effects of nanoparticle volume fraction, inclined angle, Lorentz, and buoyancy forces on the MHD nanofluid flow. The results indicate that the convection mechanism becomes weaker with an increase in solid nanoparticle volume fraction. A significant increase in the Rayleigh number will lead to a stronger and more cohesive core vortex. In addition, when magnetic force is applied horizontally, favorable Nuave occurs. Based on the numerical results, a correlation to predict the average Nusselt number within the enclosure is developed as a function of Hartmann number (Ha), Rayleigh number (Ra), and inclined angle (γ).
30 citations
TL;DR: In this paper , a micropolar fluid medium channel in the presence of mixed and nonlinear convection with the assumptions of thermal radiation and species reactive agents is considered. And the nonlinear governing equations are converted into ordinary differential equations using appropriate similarity variables with the Runge-Kutta-Fehlberg method.
Abstract: The present theoretical investigation is conducted on a micropolar fluid medium channel in the presence of mixed and nonlinear convection with the assumptions of thermal radiation and species reactive agents. The nonlinear governing equations, which describe the micropolar fluid flow and energy, are converted into ordinary differential equations using appropriate similarity variables. With the Runge–Kutta–Fehlberg method, the resultant equations are numerically solved. The physical characteristics of flow restrictions over velocity, microrotation, energy, and concentration profile are plotted and discussed. Further, the impact of several dimensionless parameters on Nusselt and Sherwood numbers is investigated and depicted graphically. In addition to observing flow patterns, contour plots of streamlines are plotted and discussed. It is demonstrated that the dimensionless velocity, temperature, and concentration of micropolar fluid have a maximum value at the center of the channel. However, the microrotation velocity of the micropolar fluid has both maxima and minima. The thermal and solutal properties of micropolar fluid influence heat and mass transport rates, that is, mixed convection and buoyancy parameter boost up the local heat transfer at the surface. Finally, Péclet number and chemically reactive parameters boost up the local mass transfer at the surface.
19 citations
TL;DR: In this paper , the energy and mass dissemination rate have been studied through Williamson hybrid nanofluid (NF) flow comprised of silver (Ag) and magnesium oxide (MgO) nanoparticles (NPs) past over an extending porous surface.
Abstract: The energy and mass dissemination rate have been studied through Williamson hybrid nanofluid (NF) flow comprised of silver (Ag) and magnesium oxide (MgO) nanoparticles (NPs) past over an extending porous surface. The hybrid nanofluid has synthesized by dispersion of Ag and MgO nanoparticles in the base fluid (engine oil). The effects of the constant magnetic field, thermal dissipation, and heat source are also studied in the present analysis. The above scenario has been designed in the form of a nonlinear system of partial differential equations, which are processed through a similarity framework to the system of dimensionless ordinary differential equations. The results are obtained by the numerical computational approach parametric continuation method. It has been perceived that the velocity contour decreases with rising upshots of porosity parameter Kp and magnetic force M, while enhances with the variation of volume friction coefficient. The increment of Biot number Bi, heat source Q, and Eckert number Ec enhances the energy profile, respectively. Furthermore, the mass conversion rate decreases with the variation of thermophoretic parameters and Schmidt number.
17 citations
TL;DR: In this article , a study of three-dimensional couple stress Casson fluid flow with nonlinear thermal radiation and heat source effects is performed using similarity transformations. And the obtained equations are found numerically via the shooting technique as well as Runge-Kutta-Fehlberg method in MATLAB software.
Abstract: This study is a study of three‐dimensional couple stress Casson fluid flow with nonlinear thermal radiation and heat source effects. The convective heat and mass transfer analysis is applied to a porous stretching sheet. In fluid flow direction, a uniform magnetic field can be applied. Using the similarity transformations, nondimensional expressions are achieved. The obtained equations are found numerically via the shooting technique as well as Runge‐Kutta‐Fehlberg method in MATLAB software. The contribution of different physical parameters is explored and discussed. Such parameters are porous parameter, couple stress parameter, heat source parameter, nonlinear thermal radiation, temperature parameter, and Lewis number. We found, the decreasing rate of heat transfer in the case of couple stress fluid motion when comparing Casson fluid flow with various values of Γ1 ${\Gamma }_{1}$ and Pr $\text{Pr}$ .
17 citations
TL;DR: In this paper , the effect of viscous dissipation and nonlinear thermal radiation on the study of ferrofluid flow and heat transfer past a porous rotating disk is explored computationally with help of Maple software.
Abstract: The prime concern of the current findings includes the effect of viscous dissipation and nonlinear thermal radiation on the study of ferrofluid flow and heat transfer past a porous rotating disk. The time‐independent flow of incompressible ferrofluid is modeled for the considered geometry, and via similarity transformations, the given system is converted to a dimensionless system of the nonlinear ordinary differential equations. Here, the findings are explored computationally with help of Maple software. The study exhibits the effect of the involved emerging parameters: the interaction parameter B $B$ , Prandtl number P r $Pr$ , rotation parameter R $R$ , radiation parameter Q r $Qr$ , Eckert number E c $Ec$ , and these are discussed graphically. Moreover, the numerical values of heat transfer rate and skin frictions are also presented in tabular form. From the perspective of numerical findings, it is perceived that the radial flow is dominant when we increase the rotation of the disk. Furthermore, the magnitude of magnetic‐fluid temperature is enhanced with the surge in the magnetic field, viscous dissipation, and thermal radiation mechanism. Finally, the current research can successfully fill a gap in the existing literature.
16 citations
TL;DR: In this article , the thermophoresis and Brownian motion effects in nanofluid flow over a curved stretching sheet (CSS) were investigated, and the Cattaneo-Christov heat flux and Stefan blowing conditions were considered for studying heat and mass transport characteristics.
Abstract: The present work investigates the thermophoresis and Brownian motion effects in nanofluid flow over a curved stretching sheet (CSS). Also, the Cattaneo–Christov heat flux and Stefan blowing (SB) conditions are considered for studying heat and mass transport characteristics. The present work's novelty is associated with considerations of convective boundary and SB conditions in nanomaterial flow over a CSS. The coupled partial differential equations are changed to ordinary differential equations by employing suitable similarity variables, and the resultant model is numerically handled using Runge–Kutta–Fehlberg's fourth fifth‐order method with the shooting scheme. The stimulation of the involved parameters/numbers on the flow, mass, and heat fields is broadly deliberated using suitable graphs. The present analysis's significant relevant outcomes are that the inclination in thermophoresis and Brownian motion parameters increases the heat transfer. The inclined values of the Brownian motion parameter decay the mass transfer. Furthermore, the increased values of both Schmidt number and SB parameter drop the mass transport. The increased values of the Brownian motion parameter and Schmidt number decays the rate of mass transference.
15 citations
TL;DR: In this paper , the authors examined the magnetohydrodynamic mixed convection Casson fluid flow over an inclined flat plate along with the heat source/sink and found that the temperature of the fluid becomes lower for local temperature Grashof number and solutal Grashoff number and that the skin fraction coefficient is greater for both the Dufour number and Soret number.
Abstract: The purpose of this study is to examine the magnetohydrodynamic mixed convection Casson fluid flow over an inclined flat plate along with the heat source/sink. The present flow problem is considered under the assumption of the chemical reaction and thermal radiation impacts along with heat and mass transport. The leading nonlinear partial differential equations of the flow problem were renovated into the nonlinear ordinary differential equations (ODEs) with the assistance of appropriate similarity transformations and then we solved these ODEs with the employment of the bvp4c technique using the computational software MATLAB. The consequences of numerous leading parameters such as thermophoretic parameter, local temperature Grashof number, solutal Grashof number, suction parameter, magnetic field parameter, Prandtl number, chemical reaction parameter, Dufour number, Soret number, angle of inclination, radiation parameter, heat source/sink, and Casson parameter on the fluid velocity, temperature, and concentration profiles are discoursed upon and presented through different graphs. Some important key findings of the present investigation are that the temperature of the Casson fluid becomes lower for local temperature Grashof number and solutal Grashof number. It is initiated that the Casson fluid parameter increases the velocity of the fluid whereas the opposite effect is noticed in the temperature profile. Higher estimation of Prandtl number and magnetic parameter elevated the Casson fluid concentration. Finally, the skin friction coefficient, Nusselt number, and Sherwood number are calculated and tabulated. It is also examined that the Nusselt number is weakened for both the Dufour number and Soret number but the skin fraction coefficient is greater for both the Dufour number and Soret number.
15 citations
TL;DR: In this article , the authors explored the entropy generation analysis on unsteady nonlinear radiative ethylene glycol-based Casson nanofluid flow near stagnation point towards a stretching sheet through a porous medium.
Abstract: This study explores the entropy generation analysis on unsteady nonlinear radiative ethylene glycol‐based Casson nanofluid flow near stagnation point towards a stretching sheet through a porous medium. Analysis has been accomplished in the presence of an inclined magnetic field, heat generation, homogeneous–heterogeneous reactions, and viscous dissipation with velocity slip and convective boundary conditions. The nondimensional governing equations are solved by the shooting technique with the help of the RK45 method. We have experimented with copper and silver nanoparticles and a comparative analysis has been highlighted for both copper and silver nanofluids. Numerical outcomes are executed by the MATLAB built‐in bvp4c function. The consequences of the experiment for various pertinent flow parameters are portrayed by graphs and tables for both the Ag‐ and Cu‐Casson nanofluids. Results reveal that the enhancement of nanoparticles volume fraction accelerates temperature but it slows down concentration and velocity distributions. Higher values of the Eckert number boost velocity and temperature but reduce skin friction coefficient and Nusselt number. Enhancement of the Brinkman number boosts up entropy generation but it slows down Bejan's number. The results of the model can be applied in the movement of biological fluids, separation of biomolecules, glass manufacturing, paper production, food processing, crude oil purification, polymer drag reduction, and cooling atomic reactors.
14 citations
TL;DR: In this paper , a phase-changing material (PCM) based air heat exchanger using a metal foam inside the heat transfer fluid (HTF) channel was examined, and the results showed that the presence of the porous medium in the system improved the discharging process by 116% compared with a nonporous medium system at the same flow rate.
Abstract: This study examines the energy discharge of a phase‐changing material (PCM)‐based air heat exchanger using a metal foam inside the heat transfer fluid (HTF) channel. Such systems have various potential applications in the heating space and building ecosystem. Thermal energy storage (TES) often utilizes air as the HTF, which limits the heat transfer performance due to the low thermal conductivity. This paper aims to address this drawback via incorporating a metal foam into the HTF channel to enhance the thermal performance between the heat transfer fluid (air) and the PCM, which is considered as the novel side of this study. The combined system is mathematically modeled with an symmetrical, three‐dimensional computational fluid dynamics method for various flow rates and inlet temperatures of the HTF with different geometric parameters of the metal foam. This study indicates the advantage of utilizing the porous medium in the air channel. The results show the HTF flow rate has a great influence on the discharging rate. The presence of the porous medium in the system improves the discharging process by 116% compared with a non‐porous medium system at the same flow rate. The discharging time decreases by increasing the porosity, and the value of 90% is found as the best porosity value at the flow rate of 0.005 kg/s in this system. The solidification rate is proportional to the pore density because of the surface area impacts of the porous medium, also the pressure‐drop and the pumping required are highly affected by the mentioned dependent parameters.
11 citations
TL;DR: In this paper , the impacts of heat generation and heat generation/absorption on convective fluid flow occasioned by a lid-driven square enclosure housing an elliptic cylinder have been investigated numerically.
Abstract: The impacts of MHD and heat generation/absorption on lid‐driven convective fluid flow occasioned by a lid‐driven square enclosure housing an elliptic cylinder have been investigated numerically. The elliptic cylinder and the horizontal enclosure boundaries were insulated and the left vertical lid‐driven wall was experienced at a fixed hot temperature, and the right wall was exposed to a fixed cold temperature. COMSOL Multiphysics 5.6 software was used to resolve the nondimensional equations governing flow physics. A set of parameters, such as Hartmann number ( 0 ≤ Ha ≤ 50 $0\le {Ha}\le 50$ ), Reynolds number ( 1 0 2 ≤ Re ≤ 1 0 3 $1{0}^{2}\le {Re}\le 1{0}^{3}$ ), Grashof number ( 1 0 2 ≤ Gr ≤ 1 0 5 $1{0}^{2}\le {Gr}\le 1{0}^{5}$ ), heat generation‐absorption parameter ( − 3 ≤ J ≤ 3 $-3\le J\le 3$ ), and elliptical cylinder aspect ratio (AR) ( 1.0 ≤ AR ≤ 3.0 $1.0\le {AR}\le 3.0$ ) have been investigated. The current study discovered that for low Reynolds number, the adiabatic cylinder AR of 2.0 provided the optimum heat transfer enhancement for the model investigated, also the impact of cylinder size diminishes beyond Gr = 104. But for high Reynolds (Re = 1000), the size of the cylinder with AR = 3.0 offered the highest heat transfer augmentation. The clockwise flow circulation reduces because of an increase in AR, which hinders the flow circulation. In addition, heat absorption supports heat transfer augmentation while heat generation can suppress heat transfer improvement.
11 citations
TL;DR: In this paper , the authors introduced a new solution with aid of numerical methods to the blood flow of Carreau-Yasuda fluid through a microvessel, and a resulting system of partial differential equations is simplified by the meaning of low Reynolds number and long wavelength.
Abstract: This investigation aims to introduce a new solution with aid of numerical methods to the blood flow of Carreau–Yasuda fluid through a microvessel. Swimming of gyrotactic microorganisms with nanoparticles is considered. A resulting system of partial differential equations is simplified by the meaning of low Reynolds number and long wavelength. This system of partial differential equations was formulated and transformed mathematically using new theories of differential transform method. Variable nonndimensional physical parameters effects, such as numbers of bioconvection Peclet and bioconvection Rayleigh, and so forth on velocity, temperature, and concentration distribution as well as oxytactic microorganism and oxygen concentration profiles are studied. All results are constructed in two cases of viscosity on the same figure, one of them in the case of variable parameters and the other in constant parameters. The existing study assured that the microorganism density in the direction near to the hypoxic tumor tissues regions grows with a rise in oxygen concentrations and the blood viscosity diminutions.
TL;DR: In this article , numerical simulations have been carried out in a shell and tube heat exchanger (STHX) and the computational fluid dynamics analysis was carried out with Al2O3, CuO, and SiO2 nanofluids amid 1, 3, and 5 vol.
Abstract: Among the heat exchangers (HE), the shell and tube type is being widely used in different applications like oil, chemical, and power plant Industries. The incorporation of segmental baffles (SB) improves the HE capacity from higher temperature fluid to lower temperature fluid. Nanofluids can be effectively used to enhance the heat transfer rate. In this study, numerical simulations have been carried out in a shell and tube heat exchanger (STHX). Among HE design methods, Tubular Exchanger Manufacturers Association (TEMA) standard is being used for better design by many researchers. In this paper, the computational fluid dynamics analysis was carried out with Al2O3, CuO, and SiO2 nanofluids amid 1, 3, and 5 vol. % with water emulsion to enhance the heat transfer coefficient of STHX. The nanofluid has been used in the cold fluid of the HE and on the other side hot water is used. From the results, it is noticed that with the increase of Nanofluids, the value of heat transfer coefficients is found to be increasing. The overall heat transfer coefficient has been enhanced for Al2O3, CuO, and SiO2 about 10.41%, 12.27%, and 9.56%, respectively, at 0.22 kg/s for the 5 vol. % addition. It is also depicted that the pressure drop is increasing with the incorporation of nanofluids.
TL;DR: In this article , the effect of a chemical reaction and aligned magnetic field on an unsteady magnetohydrodynamic free convection Kuvshinski fluid flow past an inclined plate through a porous medium in the presence of Soret and radiation was studied.
Abstract: The present paper studies the effect of a chemical reaction and aligned magnetic field on an unsteady magnetohydrodynamic free convection Kuvshinski fluid flow past an inclined plate through a porous medium in the presence of Soret and radiation. The plate is assumed to be embedded in a uniform porous medium and moves with a constant velocity in the flow direction in the presence of a transverse magnetic field. The systems of nondimensional governing linear partial differential equations are solved analytically by using the perturbation technique. The influences of various nondimensional parameters on the velocity, the temperature, and the concentration are discussed, as also the effects of various parameters on the skin‐friction coefficient and the rate of heat transfer in the form of Nusselt number and rate of mass transfer in the form of Sherwood number at the surface. Velocity distribution is observed to increase with an increase in viscoelastic parameter and Soret parameter, whereas it shows reverse effects in the case of the aligned magnetic field, inclined parameter, magnetic parameter, the temperature diminishes with the increase of radiation parameter and heat absorption parameter.
TL;DR: In this article , a 3D numerical study of thermal convection and acoustic waves is presented using a hybrid method consisting of two computational approaches: the lattice Boltzmann method (LBM) with multiple relaxation times for the study of the fluid behavior and the finite difference method (FDM) for the description of the thermal exchange.
Abstract: In this paper, a three‐dimensional (3D) numerical study of thermal convection and acoustic waves is presented using a hybrid method. This method consists of two computational approaches: the lattice Boltzmann method (LBM) with multiple relaxation times for the study of the fluid behavior and the finite difference method (FDM) for the description of the thermal exchange. The two approaches have been validated by studying two benchmark problems reported in the literature. The LBM was validated by simulating the flow induced by a lid‐driven cavity. The FDM was checked by simulating natural convection in a differentially heated cubic cavity filled with air. After this validation, the main focus was on the study of enhancement of the heat transfer in a 3D cavity using a vibrating acoustic source. The numerical study is performed for different values of the wave amplitude, the Rayleigh number ( Ra ${Ra}$ ), and the sound source size. It shows that the heat transfer is significantly improved for a low Ra ${Ra}$ . However, for high Ra ${Ra}$ values, natural convection cannot be neglected in front of forced convection. The transfer is also influenced by the variation of the source size. This allows obtaining the optimal size corresponding to the maximum heat exchange.
TL;DR: In this article , the performance of 40° helical baffles with Al2O3 nanofluid as working fluid was investigated for three-dimensional CFD analysis using the ANSYS FLUENT tool.
Abstract: In this study, Shell and tube heat exchanger (STHX) with 22% cut segmental baffles and helical baffles with 20°, 30°, 40° inclination angles are considered for three‐dimensional CFD analysis using the ANSYS FLUENT tool to investigate the performance of STHX. OHTC and comprehensive performance index are higher for 40° helical baffles when compared to segmental baffle and 20°, 30° helical baffle heat exchangers with water as working fluid. Hence, further investigations are carried out for 40° helical baffle heat exchangers. Numerical investigations are extended with nanofluids (Al2O3, CuO, and SiO2) at 1%, 3%, and 5% volume concentrations for each nanofluid. Under the same mass flow rates, 40° helical baffles with Al2O3 nanofluid as working fluid provided better heat transfer rates when compared to the other two nanofluids and base fluid. Also, the authors noticed that the 5% volume (vol) concentration nanofluids provided better heat transfer enhancements when compared to 1%, 3% volume concentrations, and base fluid. Enhancements (10.33%–8.24%) from lower to the higher mass flow rate in 40° HB with Al2O3 nanofluid at 5% volume concentration are observed when compared to water as base fluid.
TL;DR: It is noticed that sphere‐shaped gold nanoparticles enhance the temperature as compared to other geometries of nanoparticles, which may assist in developing the technology, smart micropumps, drugs, and device for hemodialysis and other health care applications.
Abstract: Gold nanoparticles associated with DNA, RNA, proteins, oligonucleotides, and peptides are useful in therapies and drug delivery. The present article mainatins that gold nanoparticles play a tremendous role in remedying cancer and fatal diseases. A mathematical model is proposed for the two‐dimensional motion of the couple stress nanofluid consisting of gold nanoparticles under the application of peristaltic propulsion and electroosmosis mechanisms in an asymmetric microchannel. The effects of radiation with slip boundary have been employed. The governing equations are simplified under the assumptions of low Reynolds number and long wavelength and the Poisson‐Boltzmann equation is solved under Debye–Hückel linearization. Analytical solutions for the velocity of fluid motion, nanoparticle temperature, stream function, pressure gradient, are evaluated and analyzed graphically under the effects of various physical parameters. It is notable from the analysis that raising the Brinkman number boosts the nanoparticle temperature and heat transfer coefficient which validate the physical model and analysis. Moreover, it is noticed that sphere‐shaped gold nanoparticles enhance the temperature as compared to other geometries of nanoparticles. The present study results may assist in developing the technology, smart micropumps, drugs, and device for hemodialysis and other health care applications.
TL;DR: In this article , the authors investigated the effect of the airflow rate, on-off cooling fan position, charging and discharging rate and cooling by the thermoelectric air-cooling module.
Abstract: In this paper, the temperature response of a lithium‐ion type 18650 battery pack cooled by a thermoelectric air‐cooling module is presented. The effects of the airflow rate, on‐off cooling fan position, charging and discharging rate and cooling by the thermoelectric air‐cooling module are investigated. The charging and discharging procedures with different current rates of 2 A (0.06 C), 3 A (0.09 C), and 4 A (0.12 C) are investigated. The results showed that different test conditions of the thermoelectric air‐cooling module have a substantial effect on the temperature of the battery pack. It was demonstrated that a thermoelectric air‐cooling module has a decreased battery temperature of lower than 40°C. The operating conditions of the cooling fans have a substantial effect on battery temperature. The experiment in which all the cooling fans are turned on shows a higher cooling capacity than natural air cooling by approximately 16%–57%. However, when setting the on‐off position of the fans that are installed in different positions, the cooling capacity when the fans at the inlet and thermoelectric cooling heat sink are turned on and the fan at the outlet battery pack is turned off is slightly less than that when all the cooling fans are turned on by approximately 25%–57%. Therefore, it can be selected as an optimum for cooling the battery pack due to less power consumption and noise issues. The proposed research can be implemented as a guideline for the cooling system of energy storage, such as small electric vehicle platforms, ground batteries, and solar energy storage.
TL;DR: In this article , the analytical solution of nonlinear PDE's governing the flow has been accomplished by employing a second-order multiple regular perturbation method within the stipulated boundary conditions.
Abstract: The current reconnaissance emphasis on spanwise cosinusoidally fluctuating temperature along with time deepened as well as radiation absorption on unsteady magneto‐hydrodynamics free convective heat and mass transfer boundary layer flow with viscous dissipation, constant suction normal to an infinite hot vertical porous plate in the existence of chemical reaction by means of heat generation. The analytical solution of nonlinear PDE's governing the flow has been accomplished by employing a second‐order multiple regular perturbation method within the stipulated boundary conditions. Velocity, temperature, concentration as well as Sherwood have been exemplified graphically; along with Skin friction, and Nusselt numbers are ascertained in tabular form. Eventually, it was found that velocity, temperature, and Skin friction accelerated with the accumulative values of Eckert number and radiation absorption, but conflicting results emerged in the case of Prandtl number. Contemporaneously Sherwood's number depreciated with the magnification of the chemical reaction parameter as well as the Schmidt number.
TL;DR: In this paper , the authors applied the lattice Boltzmann method associated with multiple relaxation times (LBM-MRT) to simulate the physical configurations of the studied system.
Abstract: This study focuses on the cooling of three heated obstacles with different heights mounted on the bottom of the channel wall using different aspects that influence the enhancement of the heat exchange, as is known in the concept of cooling electronic devices. The lattice Boltzmann method associated with multiple relaxation times (LBM‐MRT) was adopted to simulate the physical configurations of the studied system. In this context, the D2Q9 and D2Q5 models are applied to describe the fluid flow behavior and conjugate heat transfer, respectively. The evaluation of heat exchange between the cold fluid and three‐heated obstacles has been accurately analyzed under the effect of several parameters such as Reynolds number, obstacle spacing, and thermal conductivity ratio. In addition, the setting of two and three fluids flow inlets were also studied. The results are presented in terms of streamlines, isotherms, and local Nusselt curves. The heat transfer increases with increasing solid‐fluid thermal conductivity. It is also more pronounced for large Reynolds numbers. Moreover, the heat transfer significantly enhances for the second and third obstacles when obstacle spacing increases. The improvement of the heat transfer is performed by the implementation of several jet flows in the studied system.
TL;DR: In this paper , the authors analyzed numerically the three-dimensional flow of MNFs (Fe3O4-water, CoFe2O4 -water, Mn-ZnFe 2O4−water nanofluid) over a shrinking surface with suction and thermal radiation effects.
Abstract: Magnetic nanofluids (MNFs) have been widely applied in both biomedical and environmental sectors along with the substantial growth of numerical and experimental studies. Hence, in view of the unique properties in MNFs, the aim of this study is to analyze numerically the three‐dimensional flow of MNFs (Fe3O4–water, CoFe2O4–water, Mn–ZnFe2O4–water) over a shrinking surface with suction and thermal radiation effects. The single‐phase nanofluid model is reduced into a system of ordinary differential equations by applying the similarity transformation. The results are then, obtained using the bvp4c solver in the Matlab software. The results reveal that for the shrinking case, the Mn–ZnFe2O4–water nanofluid has the maximum thermal rate followed by CoFe2O4–water and Fe3O4–water, respectively. Meanwhile, Fe3O4–water expands the separation value of boundary layer flow greater than other tested MNFs. Besides this, the suction parameter is also a contributing factor for the thermal enhancement of all MNFs.
TL;DR: In this article , a numerical analysis on MHD fluid flow in parabolic mode has been performed to point out its significant properties, including thermal radiation, porous medium, heat generation, chemical reaction and thermal diffusion along with variable temperature and concentration.
Abstract: A numerical investigation on MHD fluid flow in parabolic mode has been performed to point out its significant properties. Thermal radiation, porous medium, heat generation, chemical reaction, and thermal diffusion along with variable temperature and concentration are taken into consideration in the analysis. The novelty of the work is the inclusion of heat generation and thermal diffusion along with exponentially varying temperature and concentration. The constituent governing equations are solved by using finite difference schemes in explicit form. The fluctuations in velocity, concentration, and temperature are observed and discussed with the help of graphs as well as numerical data. Their gradients are also calculated and analyzed the flow properties by using numerical tables. The existence of heat generation, as well as viscous dissipation, creates an increment in the temperature. The gradient of heat transfer rises with the impact of Prandtl number and decay in it is examined under the existence of a source of heat and viscous dissipation.
TL;DR: In this paper , the boundary layer phenomena of nonlinear radiative nano non-Newtonian (Casson) fluid flow caused by a stretched periphery with a periodic magnetic field and Arrhenius activation energy were analyzed.
Abstract: The focus of this study is to better understand the boundary layer phenomena of nonlinear radiative nano non‐Newtonian (Casson) fluid flow caused by a stretched periphery with a periodic magnetic field and Arrhenius activation energy. The time‐based controlling equations are translated into a suitable dimensionless form using the explicit finite difference (EFD) approach. However, to make the solution convergent, detailed stability and convergence criteria have been devised. In addition, the oscillatory form of velocity, isothermal, and streamline profiles, as well as the conventional shape of other flow fields are displayed. Using tabular analysis, a correlation between non‐Newtonian and Newtonian fluids has even been demonstrated. When the radiative heat flux is evaluated in a linear pattern rather than a nonlinear one, the Lorentz force has been demonstrated to diminish the flow profiles convincingly. Also, another finding is that when the magnetic factor is considered in the sinusoidal form it is controlling the heat transfer factors of nanofluid substantially. As a chemical reaction requires a high‐temperature mechanism to proceed, the scientific principles of activation energy are evaluated in the inclusion of thermal radiation of nonlinear patterns, and the mass transmission is severely influenced. However, in the presence of nonlinear radiation, the Brownian motion of the Casson fluid particles, as well as the thermophoresis phenomena has effectively elevated the temperature field rather than the linear one. The current study has implications for prostate cancer treatment. Nanoparticles have been used to treat cancer, and magnetic fields have been used to regulate the drug emission of the particles.
TL;DR: In this article , the effect of various physical parameters on magnetohydrodynamic Williamson nanofluid boundary layer flow past a wedge through porous media taking a non-Darcy-Falkner-Skan model with consideration of varying wall temperature, variable viscosity, and thermophoresis in the presence of heat source.
Abstract: The present analysis is done for the investigation of the effect of various physical parameters on magnetohydrodynamic Williamson nanofluid boundary layer flow past a wedge through porous media taking a non‐Darcy–Falkner–Skan model with consideration of varying wall temperature, variable viscosity, the effect of Brownian motion, and thermophoresis in the presence of heat source. The corresponding governing equations under the appropriate boundary conditions are first converted into ordinary differential equations (ODEs) in view of similarity transformations. Application of shooting method has been made to deal with these ODEs, and the effects of various parameters on nondimensional velocity, temperature, and concentration are investigated through graphs. Also, the effects of various parameters on surface skin friction, heat, and mass transfer rates are analyzed and are shown in Table 3. It has been noticed that heat and mass transfer rates are enhanced with variable viscosity coefficient and reduced with Brownian motion and thermophoresis parameters. As a significant outcome, the skin friction is found to be increased with increasing values of the Williamson parameter while it is found to be decreased with increasing value of variable viscosity coefficient. At last, validation of the current findings is attended to after comparing with similar results obtained earlier.
TL;DR: In this paper , the heat and mass transport behavior of transient magnetohydrodynamics second-grade fluid (elastico-viscous fluid) flow within a vertical channel bounding the porous regime with the Hall phenomenon and induced magnetic field (IMF).
Abstract: The focus of this paper is to examine the heat and mass transport behavior of transient magnetohydrodynamics second‐grade fluid (elastico‐viscous fluid) flow within a vertical channel bounding the porous regime with the Hall phenomenon and induced magnetic field (IMF). The flow system consists of a strong transverse magnetic field that gives rise to the Hall phenomenon and IMF. The right vertical surface of the channel is conducting and oscillations in its plane in the vertical direction while the left vertical surface of the channel is nonconducting and stationary. The suitable dimensionless setup transforms the flow model into a simplified comparable model which is solved analytically with the assistance of the method of separation of variables. Numerical computation is performed with the aid of MATHEMATICA software to explore the results from the analytical solutions. The results of the investigation are helpful in analyzing the nature of the elastic‐viscous fluids. A noteworthy result noted from the investigation is that there appears a reverse flow in the direction of normal flow when the magnetic interaction parameter is large. For the small magnetic interaction parameter, such a flow is not seen. Hall current reduces the strength of the principal IMF and induces the strength of the secondary generated magnetic field. Furthermore, it is explored that the elastico‐viscous nature of the second‐grade fluid has a tendency of enhancing the principal flow and principal‐produced magnetic field.
TL;DR: In this article , the authors focused on the magnetohydrodynamics flow of a viscous nanofluid over a stretching wedge with the boundary convective conditions, thermal radiation, and ohmic heating.
Abstract: The present numerical investigation has focused on the magnetohydrodynamics flow of a viscous nanofluid over a stretching wedge with the boundary convective conditions, thermal radiation, and ohmic heating. Buongiorno's two‐component nonhomogeneous nanoscale model was used and a dilute nanofluid with spherical type particles is considered. Similarity transformations are used to render the system of governing partial differential equations into a system of coupled similarity equations. The transformed equations are solved numerically with the BVP4C method. Validation of solutions with previous studies based on special cases of the general model is included. The salient features of fluid velocity profile, temperature as well as concentration profiles are discussed in a graphical manner for various values of selected governing factors. The skin friction coefficient, mass, and heat transfer rates are calculated and summarized. It is worthwhile noticing that the validation results exhibit an excellent agreement with already existing reports. The modeling of the present problem is useful in the thermal processing of sheet‐like substances that is a necessary operation in paper procurement, wire drawing, drawing of plastic films, polymeric sheets, and metal spinning.
TL;DR: In this article , the entropy generation analysis of electromagnetohydrodynamic radiative Casson flow induced by a stretching Riga plate in a non-Darcian porous medium under the influence of internal energy change, Arrhenius activation energy, chemical reaction, and melting heat transfer is examined.
Abstract: Minimizing entropy generation is a technique that helps improve the effectiveness of real processes by studying the associated irreversibility of system performance of nanofluid. This study examines the entropy generation analysis of electromagnetohydrodynamic radiative Casson flow induced by a stretching Riga plate in a non‐Darcian porous medium under the influence of internal energy change, Arrhenius activation energy, chemical reaction, and melting heat transfer. The thermophysical features of the fluid are assumed constant in most of the literature. However, this current research bridges this gap by considering viscosity, conductivity, and diffusivity as temperature‐dependent variables. Also, the exponential decaying Grinberg term is used as a resistive force in this investigation due to the electromagnetic properties of the Riga plate in the momentum conservation equation. Some suitable dimensionless variables are introduced to remodel the transport equations into unitless ones and then solved numerically by employing Galerkin Weighted Residual Method. Analyses reveal that the Casson parameter declines the fluid velocity, while the existence of the melting parameter has the opposite effect. Also, this article includes some future recommendations.
TL;DR: In this article , the effect of variable gravity on rotating convection in a sparsely packed porous layer is studied numerically for free-free and rigid-rigid boundaries using bvp4c in MATLAB R2020b.
Abstract: The effect of variable gravity on rotating convection in a sparsely packed porous layer is studied numerically. For gravity force variation, the linear, parabolic, cubic, and exponential functions are considered. Boundary conditions for the governing equations are considered to be either free or rigid. The normal mode method is employed, and the resulting eigenvalue problem is solved numerically for free–free and rigid–rigid boundaries using bvp4c in MATLAB R2020b. The influence of Darcy number ( D a $Da$ ), gravity variation parameter ( δ 1 ${\delta }_{1}$ ), and Taylor number ( T a $Ta$ ) on the stability of the system is investigated graphically. It is confirmed that the gravity variation parameter and Taylor number delay the onset of convection and Darcy number enhances the onset of convection. The size of convection cells decreases on raising the variable gravity parameter and rotation parameter, while the Darcy number amplifies the size of convection cells. It is also observed that the system is stable for exponential gravity function and less stable for the cubic gravity function.
TL;DR: In this paper , the authors considered an unsteady magnetohydrodynamics nanofluid flow with thermo-diffusion and heat generation effects, where the fluid flow at the plate is considered exponentially accelerated through a porous medium.
Abstract: In this paper, unsteady magnetohydrodynamics nanofluid flow with thermo‐diffusion and heat generation effects is studied. The fluid flow at the plate is considered exponentially accelerated through a porous medium. The governing system of equations is made dimensionless with the help of similarity transformation. A Caputo–Fabrizio fractional‐order derivative is employed to generalize the momentum, energy, and concentration equations, and the exact expression is obtained using Laplace transformation techniques. To realize the physics of the problem, numerical results of velocity, temperature, and concentration profiles are obtained and presented through graphs. Also, the numerical values of the Nusselt number and Sherwood number are obtained and compared which strongly agree with the previous studies. From the results, it is concluded that velocity distribution decline by improving the value of the chemical reaction and magnetic field while the reverse trend is observed for volume fraction and micropolar parameter. It is also seen that the heat transfer process improves with heat generation and thermal radiation whereas, mass transfer declines with the chemical reaction parameter.
TL;DR: In this paper , the effect of wall slip on third-grade liquid flow through an inclined peristaltic channel is investigated, where the variation in viscosity and thermal conductivity are taken into account, along with wall properties.
Abstract: The current model investigates the effect of wall slip on third‐grade liquid flow through an inclined peristaltic channel. The variation in viscosity and thermal conductivity are taken into account, along with wall properties. The governing equations are simplified using long wavelength and small Reynolds number approximations. The transformed equations are solved by using the perturbation technique. Physiological quantities such as velocity, streamlines, temperature, and concentration are obtained for different parameters of interest. The findings show that increasing the variable viscosity and slip term value improves the velocity profile. Furthermore, elasticity factors help flow, but damping causes fluid particles to slow down. Similarly, when the slip, variable viscosity, and inclination parameter values rise, the size of the trapped bolus grows, resulting in more bolus forms. Furthermore, the inclusion of variable properties helps understand the complex rheological properties of blood flowing through narrow or micro arteries.
TL;DR: In this paper , the authors presented turbulent heat transfer performance and entropy production rate in different inwardly corrugated pipes with single-walled carbon nanotube (SWCNT)/H2O nanofluid as a working fluid using the finite volume method approach.
Abstract: This paper presents turbulent heat transfer performance and entropy production rate in different inwardly corrugated pipes with single‐walled carbon nanotube (SWCNT)/H2O nanofluid as a working fluid using the finite volume method approach. The configurations considered were circular, triangular, and trapezoidal. The SWCNT/H2O nanofluid was modeled using a single‐phase approach and the k − ω $k-\omega $ model was used to simulate the turbulent flow. A parametric study was carried out on the effect of Reynolds number (5 × 103 ≤ Re ≤ 3 × 104) and nanoparticle volume ratio (0% ≤ φ ≤ 0.25%) on hydrodynamic, heat transfer performance, thermal entropy production rates (TEPRs; due to mean and turbulent temperature gradients), and viscous entropy production rates (VEPRs; due to mean and turbulent velocity gradients). The results showed that the mean temperature gradient contributes most to the TEPR, compared with the turbulent temperature gradient. However, the opposite was the case for the VEPR. Furthermore, the presence of corrugation decreases the TEPR but enhanced friction factor, Nusselt number, and VEPR. For example, at a Reynolds number of 2.5 × 104, the normalized friction factor, average Nusselt number, TEPR, and VEPR (referencing a smooth pipe) in circularly, triangularly, and trapezoidal corrugated pipes are {3.86, 1.39, 0.80, 3.88}, {3.80, 1.41, 0.72, 3.98}, and {4.34, 1.55, 0.69, 4.19}, respectively.