The prime objective of the present study is to examine the effect of tempera- ture dependent viscosity/z（T） on the revolving axi-symmetric laminar boundary layer flow of an incompressible, electrically non-conductin...The prime objective of the present study is to examine the effect of tempera- ture dependent viscosity/z（T） on the revolving axi-symmetric laminar boundary layer flow of an incompressible, electrically non-conducting ferrofiuid in the presence of a stationary plate subjected to a magnetic field and maintained at a uniform temperature. To serve this purpose, the non-linear coupled partial differential equations are firstly converted into the ordinary differential equations using well-known similarity transformations. The popular finite difference method is employed to discretize the non-linear coupled differ- ential equations. These discretized equations are then solved using the Newton method in MATLAB, for which an initial guess is made with the help of the Flex PDE Solver. Along with the velocity profiles, the effects of temperature dependent viscosity are also examined on the skin friction, the heat transfer, and the boundary layer displacement thickness. The obtained results are presented numerically as well as graphically.展开更多
Heat transfers due to MHD-conjugate free convection from the isothermal horizontal circular cylinder while viscosity is a function of temperature is investigated. The governing equations of the flow and connected boun...Heat transfers due to MHD-conjugate free convection from the isothermal horizontal circular cylinder while viscosity is a function of temperature is investigated. The governing equations of the flow and connected boundary conditions are made dimensionless using a set of non-dimensional parameters. The governing equations are solved numerically using the finite difference method. Numerical results are obtained for various values of viscosity variation parameter, Prandtl number, magnetic parameter, and conjugate conduction parameter for the velocity and the temperature within the boundary layer as well as the skin friction coefficients and heat transfer rate along the surface.展开更多
This study aims to investigate turbulent plasma flow using the lattice Boltzmann(LB)method.A double population model D2Q9-D2Q4 is employed to calculate the plasma velocity and temperature fields.Along with the calcula...This study aims to investigate turbulent plasma flow using the lattice Boltzmann(LB)method.A double population model D2Q9-D2Q4 is employed to calculate the plasma velocity and temperature fields.Along with the calculation process a conversion procedure is made between the LB and the physical unit systems,so that thermo-physical properties variation is fully accounted for and the convergence is checked in physical space.The configuration domain and the boundary condition treatment are selected based on the most cited studies in order to illustrate a realistic situation.The jet morphology analysis gives credible results by comparison with commonly published works.It was demonstrated also that accounting for the substrate as wall boundary condition modify greatly the flow and temperature structures with may affect absolutely the particles behavior during its in-flight in the hot gas.展开更多
The unique chemical mechanical, and thermodynamic properties of nanofluids make them a subject of great interest for scientists from all domains. Such fluids are of particular significance in biomedical engineering ow...The unique chemical mechanical, and thermodynamic properties of nanofluids make them a subject of great interest for scientists from all domains. Such fluids are of particular significance in biomedical engineering owing to their vast and novel applications in modern drug delivery systems; for example, mixed convective peristaltic flow of water-based nanofluids under the influence of an externally applied magnetic field is of particular significance. Hence, a lot of research has focused on peristalsis in the presence of velocity and thermal slip effects. An empirical relation for the effective viscosity of the nanofluid is proposed here for the first time. The viscosity of the nanofluid varies with temperature and nanoparticle volume fraction. Numerical simulation of the resulting nonlinear system of equations is presented for different quantities of interest. The results indicate that the maximum velocity and temperature of the copper-water nanofluid increase for larger variable viscosity parameter. The pressure gradient in the wider part of the channel is also found to increase as a function of the variable viscosity parameter. The variable viscosity parameter also influences the size of the trapped bolus. An increase in the nanoparticle volume fraction reduces the reflux phenomenon in a peristaltic flow.展开更多
This study investigates the effect of nonuniform heating and temperature-dependent viscosity on transient free convective flow in a porous material adjacent to a semi-infinite upright plate.Such scenarios are relevant...This study investigates the effect of nonuniform heating and temperature-dependent viscosity on transient free convective flow in a porous material adjacent to a semi-infinite upright plate.Such scenarios are relevant to applications such as the cooling of electronic devices,solar energy systems,and geophysical processes.The governing equations are transformed into dimensionless form and subsequently solved using the CrankNicolson technique.The results reveal that velocity increases with increasing viscosity parameter(ζ=0,2,4)at all cross-sections,while the temperature decreases at x=0.25 and 0.5,but rises at x=0.75,with the maximum free-stream velocity occurring at x=0.75 forζ=2.Additionally,velocity and temperature attain their highest values near the plate,with the boundary layers growing over time.Eventually,both velocity and temperature stabilize,signifying the attainment of a steady-state condition.The local Nusselt number exhibits an increasing trend with increasing Darcy,Prandtl,and Grashof numbers,indicating improved heat transfer,while increasing viscosity contributes to a reduction in local skin friction.Moreover,nonuniform heating leads to the highest temperature at x=0.5,which decreases at x=0.75,and reaches its lowest value at x=0.25.展开更多
Neglecting the consumption of the material, a steady incompressible flow of an exothermic reacting third-grade fluid with viscous heating in a circular cylindrical pipe is numerically studied for both cases of constan...Neglecting the consumption of the material, a steady incompressible flow of an exothermic reacting third-grade fluid with viscous heating in a circular cylindrical pipe is numerically studied for both cases of constant viscosity and Reynolds＇ viscosity model. The coupled ordinary differential equations governing the flow in cylindrical coordinates, are transformed into dimensionless forms using appropriate transformations, and then solved numerically. Solutions using Maple are presented in tabular form and given in terms of dimensionless central fluid velocity and temperature, skin friction and heat transfer rate for three parametric values in the Reynolds＇ case. The numerical results for the velocity and temperature fields are also presented through graphs. Bifurcations are discussed using shooting method. Comparisons are also made between the present results and those of previous work, and thus verify the validity of the provided numerical solutions. Important properties of thermal criticality are provided for variable viscosity parameter and reaction order. Further numerical results are presented in the form of tables and graphs for transition of physical parameters, while varying certain flow and fluid material parameters. Also, the flow behaviour of the reactive fluid of third-grade is compared with those of the Newtonian reactive fluid.展开更多
A study on the effects of Navier slip, in conjunction with other flow parameters, on unsteady flow of reactive variable viscosity third-grade fluid through a porous saturated medium with asymmetric convective boundary...A study on the effects of Navier slip, in conjunction with other flow parameters, on unsteady flow of reactive variable viscosity third-grade fluid through a porous saturated medium with asymmetric convective boundary conditions is presented. The channel walls are assumed to be subjected to asymmetric convective heat exchange with the ambient, and exothermic chemical reactions take place within the flow system. The heat exchange with the ambient obeys Newton＇s law of cooling. The coupled equations, arising from the law of conservation of momentum and the first law of thermodynamics, then the derived system are non- dimensionalised and solved using a semi-implicit finite difference scheme. The lower wall slip parameter is observed to increase the fluid velocity profiles, whereas the upper wall slip parameter retards them because of backflow at the upper channel wall. Heat pro- duction in the fluid is seen to increase with the slip parameters. The wall shear stress increases with the slip parameters while the wall heat transfer rate is largely unaltered by the lower wall slip parameter but marginally increased by the upper wall slip parameter.展开更多
文摘The prime objective of the present study is to examine the effect of tempera- ture dependent viscosity/z（T） on the revolving axi-symmetric laminar boundary layer flow of an incompressible, electrically non-conducting ferrofiuid in the presence of a stationary plate subjected to a magnetic field and maintained at a uniform temperature. To serve this purpose, the non-linear coupled partial differential equations are firstly converted into the ordinary differential equations using well-known similarity transformations. The popular finite difference method is employed to discretize the non-linear coupled differ- ential equations. These discretized equations are then solved using the Newton method in MATLAB, for which an initial guess is made with the help of the Flex PDE Solver. Along with the velocity profiles, the effects of temperature dependent viscosity are also examined on the skin friction, the heat transfer, and the boundary layer displacement thickness. The obtained results are presented numerically as well as graphically.
文摘Heat transfers due to MHD-conjugate free convection from the isothermal horizontal circular cylinder while viscosity is a function of temperature is investigated. The governing equations of the flow and connected boundary conditions are made dimensionless using a set of non-dimensional parameters. The governing equations are solved numerically using the finite difference method. Numerical results are obtained for various values of viscosity variation parameter, Prandtl number, magnetic parameter, and conjugate conduction parameter for the velocity and the temperature within the boundary layer as well as the skin friction coefficients and heat transfer rate along the surface.
基金supported in part by the Ministry of Higher Education and Scientific Research of TunisiaThe first author would like to thank particularly the University of Limoges for the computational facilities provided by CALI calculation centre,and the”Fonds de dotation PERENNE”for financial supports.
文摘This study aims to investigate turbulent plasma flow using the lattice Boltzmann(LB)method.A double population model D2Q9-D2Q4 is employed to calculate the plasma velocity and temperature fields.Along with the calculation process a conversion procedure is made between the LB and the physical unit systems,so that thermo-physical properties variation is fully accounted for and the convergence is checked in physical space.The configuration domain and the boundary condition treatment are selected based on the most cited studies in order to illustrate a realistic situation.The jet morphology analysis gives credible results by comparison with commonly published works.It was demonstrated also that accounting for the substrate as wall boundary condition modify greatly the flow and temperature structures with may affect absolutely the particles behavior during its in-flight in the hot gas.
文摘The unique chemical mechanical, and thermodynamic properties of nanofluids make them a subject of great interest for scientists from all domains. Such fluids are of particular significance in biomedical engineering owing to their vast and novel applications in modern drug delivery systems; for example, mixed convective peristaltic flow of water-based nanofluids under the influence of an externally applied magnetic field is of particular significance. Hence, a lot of research has focused on peristalsis in the presence of velocity and thermal slip effects. An empirical relation for the effective viscosity of the nanofluid is proposed here for the first time. The viscosity of the nanofluid varies with temperature and nanoparticle volume fraction. Numerical simulation of the resulting nonlinear system of equations is presented for different quantities of interest. The results indicate that the maximum velocity and temperature of the copper-water nanofluid increase for larger variable viscosity parameter. The pressure gradient in the wider part of the channel is also found to increase as a function of the variable viscosity parameter. The variable viscosity parameter also influences the size of the trapped bolus. An increase in the nanoparticle volume fraction reduces the reflux phenomenon in a peristaltic flow.
文摘This study investigates the effect of nonuniform heating and temperature-dependent viscosity on transient free convective flow in a porous material adjacent to a semi-infinite upright plate.Such scenarios are relevant to applications such as the cooling of electronic devices,solar energy systems,and geophysical processes.The governing equations are transformed into dimensionless form and subsequently solved using the CrankNicolson technique.The results reveal that velocity increases with increasing viscosity parameter(ζ=0,2,4)at all cross-sections,while the temperature decreases at x=0.25 and 0.5,but rises at x=0.75,with the maximum free-stream velocity occurring at x=0.75 forζ=2.Additionally,velocity and temperature attain their highest values near the plate,with the boundary layers growing over time.Eventually,both velocity and temperature stabilize,signifying the attainment of a steady-state condition.The local Nusselt number exhibits an increasing trend with increasing Darcy,Prandtl,and Grashof numbers,indicating improved heat transfer,while increasing viscosity contributes to a reduction in local skin friction.Moreover,nonuniform heating leads to the highest temperature at x=0.5,which decreases at x=0.75,and reaches its lowest value at x=0.25.
基金supported by Pastor E. A. Adeboye endowed Professorial Chair and conducted at the Department of Mathematics, University of Lagos, Lagos, Nigeria while on leave from
文摘Neglecting the consumption of the material, a steady incompressible flow of an exothermic reacting third-grade fluid with viscous heating in a circular cylindrical pipe is numerically studied for both cases of constant viscosity and Reynolds＇ viscosity model. The coupled ordinary differential equations governing the flow in cylindrical coordinates, are transformed into dimensionless forms using appropriate transformations, and then solved numerically. Solutions using Maple are presented in tabular form and given in terms of dimensionless central fluid velocity and temperature, skin friction and heat transfer rate for three parametric values in the Reynolds＇ case. The numerical results for the velocity and temperature fields are also presented through graphs. Bifurcations are discussed using shooting method. Comparisons are also made between the present results and those of previous work, and thus verify the validity of the provided numerical solutions. Important properties of thermal criticality are provided for variable viscosity parameter and reaction order. Further numerical results are presented in the form of tables and graphs for transition of physical parameters, while varying certain flow and fluid material parameters. Also, the flow behaviour of the reactive fluid of third-grade is compared with those of the Newtonian reactive fluid.
文摘A study on the effects of Navier slip, in conjunction with other flow parameters, on unsteady flow of reactive variable viscosity third-grade fluid through a porous saturated medium with asymmetric convective boundary conditions is presented. The channel walls are assumed to be subjected to asymmetric convective heat exchange with the ambient, and exothermic chemical reactions take place within the flow system. The heat exchange with the ambient obeys Newton＇s law of cooling. The coupled equations, arising from the law of conservation of momentum and the first law of thermodynamics, then the derived system are non- dimensionalised and solved using a semi-implicit finite difference scheme. The lower wall slip parameter is observed to increase the fluid velocity profiles, whereas the upper wall slip parameter retards them because of backflow at the upper channel wall. Heat pro- duction in the fluid is seen to increase with the slip parameters. The wall shear stress increases with the slip parameters while the wall heat transfer rate is largely unaltered by the lower wall slip parameter but marginally increased by the upper wall slip parameter.
