Wyniki wyszukiwania - BazTech

1

Mixed convective flow with variable viscosity and variable thermal conductivity in a channel in the presence of first order chemical reaction with heat generation or absorption

Shobha K. C., Biradar Mahadev, Mallikarjun B Patil

Journal of Applied Mathematics and Computational Mechanics

|

2021

|

Vol. 20, nr 1

91--102

EN

A study has been made on the flow and heat transfer of a viscous fluid in a vertical channel with first order chemical reaction and heat generation or absorption assuming that the viscosity and thermal conductivity are dependent on the fluid temperature. The temperature of the walls is maintained constant. Under these assumptions, the governing balance equations of mass, momentum and energy are formulated. The dimensionless forms of the governing equations are coupled and non-linear, which cannot be solved analytically and therefore require the use of the Runge-Kutta fourth order along with shooting technique. Graphs for velocity and temperature under different values of parameters involved are plotted and discussed. The skin friction and Nusselt number on the channel walls are also computed and discussed. Furthermore, the investigation found that variable viscosity and variable thermal conductivity enhance the velocity and temperature of the flow.

2

MHD natural convection in saturated porous media with heat generation/absorption and thermal radiation: closed-form solutions

Turkyilmazoglu M.

Archives of Mechanics

|

2019

|

Vol. 71, nr 1

49--64

EN

The present work is devoted to the free convection flow occurring about a heated vertically stretching permeable surface placed in a porous medium under the influence of a temperature dependent internal heat generation or absorption. There are volume radiative heat sources in the fluid and the system is permeated by a uniform magnetic field. It is shown that the governing equations are reducible to a self-similar nonlinear ordinary differential equation of third order whose solutions are constructed analytically in the purely exponential series form. Under special circumstances, closed-form solutions are available which clearly indicate the existence of dual natural convection solutions. Otherwise, analytical solutions are still possible which are shown to be computed from an elegant algorithm without a need to invoke any numerical means. Exact solutions demonstrate, in physical insight that, in the presence of a heat sink absorbing the temperature from the porous medium increases the rate of heat transfer from the wall, whereas a heat source mechanism will surely overheat the system during the wall heating process, resulting in poor heat transfer rates. The presented exact solutions are beneficial for investigation of free convection phenomena in different geometries taking into account more complex physical features in higher dimensions.

3

Time dependent natural convection Couette flow of heat generating/absorbing fluid: accelerated motion

Jha B. K., Ajibade A. O.

International Journal of Applied Mechanics and Engineering

|

2010

|

Vol. 15, no 4

1083-1100

EN

The unsteady Couette flow in a channel formed by two vertical parallel plates is investigated in the presence of internal heat generation/absorption. The flow is set up due to time dependent motion of one of the plates coupled with asymmetric heating of the infinite vertical parallel plates. Analytical solutions of the resulting partial differential equations are obtained using the Laplace transforms technique. The numerical values obtained from the analytical expressions for temperature, velocity, Nusselt number, skin-friction and mass flux are presented graphically to study the flow behaviour in the presence of the governing parameters. It is interesting to note that in the absence of convection currents (Gr=0) the flow is dependent only on the motion of one of the channel plates. The influence of the heat generation/absorption parameter on the rate of heat transfer on one plate is the exact opposite of the influence on the other plate while its influence on the skin-friction is identical on both plates. In the presence of external cooling, the mass flux diverges as time increases, while it converges to zero in the case of external heating.

4

Effect of magnetic field and heat generation/absorption on free convection along semi-infinite vertical porous plate

Tak S. S., Gehlot R. K., Mathur R.

International Journal of Applied Mechanics and Engineering

|

2010

|

Vol. 15, no 1

237-248

EN

Heat and momentum transfer in the case of a steady free convection flow along a semi-infinite vertical porous/non-porous plate in the presence of a uniform transverse magnetic field and uniform heat generation/absorption have been investigated. Non-similar solutions of the governing equations have been obtained by taking series expansions of stream function and temperature function. The resulting set of non-linear coupled ordinary differential equations with the appropriate boundary conditions has been solved numerically, using Newton's shooting technique. Numerical values of functions that correspond to the local wall shear stress and the rate of surface heat transfer are tabulated. The velocity function, temperature function, local skin-friction and local Nusselt number are shown graphically for various values of parameters involved and discussed in detail.