Micromagnetorotation of MHD Micropolar Flows

The studies dealing with micropolar magnetohydrodynamic (MHD) flows usually ignore the micromagnetorotation (MMR) effect, by assuming that magnetization and magnetic field vectors are parallel. The main objective of the present investigation is to measure the effect of MMR and the possible differences encountered by ignoring it. The MHD planar Couette micropolar flow is solved analytically considering and by ignoring the MMR effect. Subsequently, the influence of MMR on the velocity and microrotation fields as well as skin friction coefficient, is evaluated for various micropolar size and electric effect parameters and Hartmann numbers. It is concluded that depending on the parameters’ combination, as MMR varies, the fluid flow may accelerate, decelerate, or even excite a mixed pattern along the channel height. Thus, the MMR term is a side mechanism, other than the Lorentz force, that transfers or dissipates magnetic energy in the flow direct through microrotation. Acceleration or deceleration of the velocity from 4% to even up to 45% and almost 15% deviation of the skin friction were measured when MMR was considered. The crucial effect of the micromagnetorotation term, which is usually ignored, should be considered for the future design of industrial and bioengineering applications.

Behaviors of Micropolar Flows in a Rotating Annulus

An analysis is presented for the problem of micropolar flows in the annulus between two steadily rotating concentric cylinders. The local effects arising from microstructure and intrinsic motion of the fluid element that will affect the flow motion are considered. Especially, the effects of non-zero values of micro-gyration vector on the wall boundary conditions are investigated, using micropolar fluid theory. Numerical results of velocity distribution of micropolar fluids are compared with the corresponding flow problems for a Newtonian fluid. Also, the results of the surface friction coefficient and the couple stress coefficient at the inner and outer surfaces are prepared with various values of fluid properties and flow conditions.