g-Jitter induced free convection boundary layer on heat transfer from a sphere with constant heat flux

The free convection from a sphere, which is subjected to a constant surface heat flux in the presence of g-jitter is theoretically investigated in this paper. The governing equations of motion are first non-dimensionalized and the resulting equations obtained after the introduction of vorticity are solved numerically using an implicit finite difference method for a limiting case Re >> 1 or the boundary layer approximations. Table and graphical results for the skin friction and wall temperature distributions as well as for the velocity and temperature profiles are presented and discussed for various parametric physical conditions Prandtl number, Pr=0.72, 1 and 7. Results indicate that g-jitter induced convective flows is stronger when Pr is small

Energy Transfer in Mixed Convection MHD Flow of Nanofluid Containing Different Shapes of Nanoparticles in a Channel Filled with Saturated Porous Medium

Energy transfer in mixed convection unsteady magnetohydrodynamic (MHD) flow of an incompressible nanofluid inside a channel filled with a saturated porous medium is investigated. The walls of the channel are kept at constant temperature, and uniform magnetic field is applied perpendicular to the direction of the flow. Three different flow situations are discussed on the basis of physical boundary conditions. The problem is first written in terms of partial differential equations (PDEs), then reduces to ordinary differential equations (ODEs) by using a perturbation technique and solved for solutions of velocity and temperature. Four different shapes of nanoparticles inside ethylene glycol (C2H6O2) and water (H2O)‐based nanofluids are used in equal volume fraction. The solutions of velocity and temperature are plotted graphically, and the physical behavior of the problem is discussed for different flow parameters. It is evaluated from this problem that viscosity and thermal conductivity are the dominant parameters responsible for different consequences of motion and temperature of nanofluids. Due to greater viscosity and thermal conductivity, C2H6O2‐based nanofluid is regarded as better convectional base fluid assimilated to H2O

Hydromagnetic Falkner-Skan flow of Casson fluid past a moving wedge with heat transfer

AbstractNumerical solutions are carried out for steady state two dimensional electrically conducting mixed convection flow of Casson fluid along non-isothermal moving wedge through porous medium in the presence of viscous dissipation and heat generation/absorption. The governing partial differential equations, subject to boundary conditions are transformed into ordinary differential equations using similarity transformations. The transformed equations are then solved numerically by Keller-box method. To check the validity of present method, numerical results for dimensionless local skin friction coefficient and rate of heat transfer are compared with results of available literature as special cases and revealed in good agreement. The influence of pertinent parameters on velocity, temperature profiles, as well as wall shear stress and heat transfer rate is displayed in graphical form and discussed. It is found that fluid velocity increases with increase of Eckert number in case of assisting flow, while it decreases in case of opposing flow. It is also noticed that heat generation/absorption parameter influence fluid velocity and temperature significantly. A significant result obtained from this study is that heat transfer rate reduces with increase of Prandtl number in the presence of viscous dissipation effect. Also, increasing values of Eckert number have no effects on force convection flow

MHD free convection flow over an inclined plate that applies arbitrary shear stress to the fluid

An exact analysis of heat transfer past an infinite inclined plate that applies arbitrary shear stress to the fluid with Newtonian heating is presented, The fluid is considered electrically conducting and passing through a porous medium, The influence of thermal radiation in the enerh'Y equations is also considered, General solutions of the problem are obtained in closed form using the Laplace transform technique, They satisfy the governing equations, initial and boundary conditions and can set up a huge number of exact solutions correlatives to various fluid motions, The effects of various parameters on velocity and temperature profiles are shown graphically and discussed in details

Effects of Newtonian heating and mass diffusion on MHD free convection flow over vertical plate with shear stress at the wall

Effects of Newtonian heating and mass diffusion on magnetohydrodynamic free convection flow over a vertical plate that applies arbitrary shear stress to the fluid is studied. The fluid is considered electrically conducting and passing through a porous medium. The influence of thermal radiation in the energy equations is also considered. General solutions of the problem are obtained in closed form using the Laplace transform technique. They satisfy the governing equations, initial and boundary conditions and can set up a huge number of exact solutions correlatives to various fluid motions. The effects of various parameters on velocity profiles are shown graphically and discussed in details

Radiation and heat generation effects in magnetohydrodynamic mixed convection flow of nanofluids

Radiation and heat generation effects in unsteady magnetohydrodynamic mixed convection flow of nanofluids along a vertical channel are investigated. Silver nanoparticles of spherical shapes and of different sizes in water as a convection-al base fluid are incorporated. The purpose of this study is to measure the effect of different sizes of nanoparticles on velocity and temperature. Keeping in mind the size, particle material, shape, clustering and Brownian motion of nanoparti-cles, Koo and Kleinstreuer model is used. The problem is modeled in terms of partial differential equations with physical boundary conditions. Analytical solu-tions are obtained for velocity and temperature, plotted and discussed. It is con-cluded that increasing the size of Ag nanoparticles (up to specific size, 30 nm, re-sults in a very small velocity increment while for large particle size (30-100 nm), no change in velocity is observed. As the small size of nanoparticles has the high-est thermal conductivity and viscosity. This change in velocity with size of nano-particles is found only in water-based nanofluids with low volume fraction 0.01 while at low volume concentration, no change is observed

MHD Mixed Convection Flow of Casson Fluid over a Moving Wedge Saturated in a Porous Medium in the presence of Chemical Reaction and Convective Boundary Conditions

This work concerned to hydromagnetic mixed convection flow of Casson fluid over a wedge. It is assumed that the wedge is moving inside a porous medium. The effects of chemical reaction, slip and convective boundary conditions at velocity, temperature and concentration walls are also considered. The governing partial differential equations are converted into ordinary differential equations using similarity transformations, and then solved by implicit finite difference scheme. Comparisons with the existing literature are performed and good agreement is achieved. The influence of physical parameters on flow fields are illustrated graphically. It is observed that the velocity rises with the increment in Casson fluid parameter and magnetic parameter. It is also noticed that thickness of thermal boundary layer grows with the increase of radiation. The skin friction coefficient enhances with the increase of porosity parameter while reduces as Casson fluid and moving wedge parameters increase. Increase in heat and mass transfer rate is noticed to be enhanced with the increase in radiation and chemical reaction parameters, respectively

Double diffusion on unsteady magnetohydrodynamic free convection flow in a rotating medium

The heat and mass transfer on the unsteady radiative magnetohydrodynamic (MHO) free convection flow over an impulsively started vertical plate in a rotating medium is studied. The fluid is considered gray, absorbing-emitting but non-scattering medium and the Rosseland approximation is used to describe the radiative heat flux in this analysis. The Laplace transform technique is used to obtain the exact solutions of the governing equations. The numerical results of fluid velocity, fluid temperature, fluid concentration, and skin friction, as well as the rate of heat transfer and the rate of mass transfer at the plate are displayed through graphs and tables in order to see the effects of the various parameters involved. The present results obtained here may be used to verify the validation of obtained numerical solutions for more complicate fluid flow problems

Stagnation point flow of MHD dusty fluid toward stretching sheet with convective surface

This paper presents the study of stagnation point of hydromagnetic flow of dusty fluid over a stretching sheet with the bottom surface of sheet heated by convection from hot fluid. The governing partial differential equations are transformed into a system of nonlinear ordinary differential equations using similarity transformation. These resulting nonlinear ordinary differential equations are solved numerically by using Runge-Kutta Fehlberg fourth-fifth order method (RKF45 Method). The characteristics of velocity and temperature profiles of hydromagnetic fluid flow of dusty fluid are analyzed and discussed for different parameters of interest such as convective Biot number, fluid-particle interaction parameter, magnetic parameter, ratio of free stream velocity parameter and Prandtl number on the flow. The numerical results are compared with previous published results for validation

Slip effect on an unsteady MHD stagnation-point flow of a micropolar fluid towards a shrinking sheet with thermophoresis effect

The effect of slip and thermophoresis on an unsteady magnetohydrodynamic stagnation-point-flow micropolar fluid with heat and mass transfer towards a shrinking sheet has been investigated. The governing equations are reduced to a system of non-dimensional partial differential equations by using similarity transformation, before being solved numerically using the Keller-box method. The effects of various physical parameters on the velocity, microrotation, temperature, and concentration profiles as well as the reduced skin friction, the reduced Nusselt number, and the reduced Sherwood number are analyzed and discussed graphically. It is found that the concentration boundary layer thickness decreases with increasing values of the thermophoresis. Comparison with previously published results under the limiting cases is made and found to be in excellent agreement