FERROFLUID FLOW WITH MAGNETIC FIELD-DEPENDENT VISCOSITY DUE TO ROTATING DISK IN POROUS MEDIUM

2012 ◽  
Vol 04 (04) ◽  
pp. 1250041 ◽  
Author(s):  
PARAS RAM ◽  
VIKAS KUMAR

The present study is carried out to examine the effects of magnetic field-dependent viscosity on steady axi-symmetric ferrofluid flow due to rotating disk in porous medium. The momentum equations give rise to highly nonlinear partial differential equations, which are converted to a system of nonlinear coupled ordinary differential equations on using Karman's similarity transformation. Then a numerical technique, which is the combination of finite difference and shooting methods, is employed in MATLAB environment to get the numerical solution of the problem. Beside the velocity and pressure profiles, the effect of MFD viscosity parameter and porosity parameter are also examined on radial, tangential skin frictions and on boundary layer displacement thickness. The results thus obtained numerically over the entire range of physical parameters are presented graphically.

2014 ◽  
Vol 06 (04) ◽  
pp. 1450033 ◽  
Author(s):  
PARAS RAM ◽  
VIKAS KUMAR

The purpose of present study is to investigate the effects of field dependent viscosity on swirling flow of an incompressible electrically non-conducting ferrofluid over a porous rotating disk with suction and heat transfer at the wall. Karman's similarity transformations are used to convert the governing boundary layer equations involved in the problem to a system of nonlinear coupled differential equations. The solution of this system is obtained by using a second-order numerical scheme which combines the features of Finite Difference method and Newton's zero finding algorithms. The flow characteristics including velocity and temperature profiles and boundary layer displacement thickness are studied for various values of MFD (magnetic field dependent) viscosity and suction parameter. Beside these, skin friction coefficients and the rate of heat transfer are also calculated on the surface of the disk. Magnetic field dependent viscosity and suction at the surface of porous rotating disk affect significantly the velocity and temperatures fields, rate of heat transfer and other flow characteristics in the generated ferrofluid boundary layer.


2014 ◽  
Vol 19 (1) ◽  
pp. 61-77
Author(s):  
R. Hemalatha

Abstract The effect of a magnetic field dependent viscosity on a Soret driven ferro thermohaline convection in a rotating porous medium has been investigated using the linear stability analysis. The normal mode technique is applied. A wide range of values of the Soret parameter, magnetization parameter, the magnetic field dependent viscosity, Taylor number and the permeability of porous medium have been considered. A Brinkman model is used. Both stationary and oscillatory instabilities have been obtained. It is found that the system stabilizes only through oscillatory mode of instability. It is found that the magnetization parameter and the permeability of the porous medium destabilize the system and the Soret parameter, the magnetic field dependent viscosity and the Taylor number tend to stabilize the system. The results are presented numerically and graphically


2020 ◽  
Vol 25 (1) ◽  
pp. 142-158
Author(s):  
J. Prakash ◽  
P. Kumar ◽  
S. Manan ◽  
K.R. Sharma

AbstractThe effect of magnetic field dependent (MFD) viscosity on the thermal convection in a ferrofluid layer saturating a sparsely distributed porous medium has been investigated by using the Darcy-Brinkman model in the simultaneous presence of a uniform vertical magnetic field and a uniform vertical rotation. A correction is applied to the study of Vaidyanathan et al. [11] which is very important in order to predict the correct behavior of MFD viscosity. A linear stability analysis has been carried out for stationary modes and oscillatory modes separately. The critical wave number and critical Rayleigh number for the onset of instability, for the case of free boundaries, are determined numerically for sufficiently large values of the magnetic parameter M1. Numerical results are obtained and are illustrated graphically. It is shown that magnetic field dependent viscosity has a destabilizing effect on the system for the case of stationary mode and a stabilizing effect for the case of oscillatory mode, whereas magnetization has a destabilizing effect.


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