DRAG ON A REINER-RIVLIN LIQUID SPHERE EMBEDDED IN A POROUS REGION PLACED IN A MICROPOLAR FLUID
R. Tamil Selvi, Pankaj Shukla, Abhishek Kumar Singh
Abstract
Consideration is given to the problem of steady axisymmetric creeping flow of a micropolar fluid around the spherical drop of non-Newtonian liquid shell covered with permeable medium. The field equations of micropolar fluids are presented in terms of velocity vector and microrotation vector. External liquid permeates into the porous layer, but it is not mixed with the liquid located in the internal cavity of a capsule. The flow inside the permeable medium is described by the Brinkman equation. The stream function solution for the external flow field is derived in terms of modified Bessel's function and Gegenbauer's polynomial. The solution is determined by dilating the stream function in terms of the dimensionless parameter S for the internal flow field (Reiner-Rivlin liquid sphere). Analytical expressions for the pressure field, coupling number, microrotation component, viscosity ratio, permeability parameter, and drag force are calculated. The effect of various parameters on the drag force is presented graphically and discussed. It is observed that the drag on a micropolar fluid sphere is more than that on a permeable sphere. Different limiting cases are also considered.