Accelerated micropolar fluid--flow past an uniformly rotating circular cylinder

In this paper, we formulated the non-steady flow due to the uniformly accelerated and rotating circular cylinder from rest in a stationary, viscous, incompressible and micropolar fluid. This flow problem is examined numerically by adopting a special scheme comprising the Adams-Bashforth Temporal Fourier Series method and the Runge-Kutta Temporal Special Finite-Difference method. This numerical scheme transforms the governing equation for micropolar fluids for this problem into system of finite-difference equations. This system was further solved numerically by point SOR-method. These results were also further extrapolated by the Richardson extrapolation method. This scheme is valid for all values of the flow and fluid-parameters and for all time. Moreover the boundary conditions of the vorticity and the spin at points far from the cylinder are being imposed and encountered too. The results are compared with existing results (for non-rotating circular cylinder in Newtonian fluids). The comparison is good. The enhancement of lift and reduction in drag was observed if the micropolarity effects are intensified. Same is happened if the rotation of a cylinder increases. Furthermore, the vortex-pair in the wake is delayed to successively higher times as rotation parameter increases. In addition, the rotation helps not only in dissolving vortices adjacent to the cylinder and adverse pressure region but also in dissolving the boundary layer separation. Furthermore, the rotation reduces the micropolar spin boundary layer also

On the performance of finite journal bearings lubricated with micropolar fluids

A study of the performance parameters for a journal bearing of finite length lubricated with micropolar fluids is undertaken. Results indicate that a significantly higher load carrying capacity than the Newtonian fluids may result depending on the size of material characteristic length and the coupling number. It is also shown that although the frictional force associated with micropolar fluid is in general higher than that of a Newtonian fluid, the friction coefficient of micropolar fluids tends to be lower than that of the Newtonian

MHD OBLIQUE STAGNATION-POINT FLOW OF A MICROPOLAR FLUID

The steady two-dimensional oblique stagnation-point flow of an electrically conducting micropolar fluid in the presence of a uniform external electromagnetic field (E0,H0) is analyzed and some physical situations are examined. In particular, if E0 vanishes, H0 lies in the plane of the flow, with a direction not parallel to the boundary, and the induced magnetic field is neglected. It is proved that the oblique stagnationpoint flow exists if, and only if, the external magnetic field is parallel to the dividing streamline. In all cases it is shown that the governing nonlinear partial differential equations admit similarity solutions and the resulting ordinary differential problems are solved numerically. Finally, the behaviour of the flow near the boundary is analyzed; this depends on the three dimensionless material parameters, and also on the Hartmann number if H0 is parallel to the dividing streamline

MHD THREE-DIMENSIONAL STAGNATION-POINT FLOW OF A MICROPOLAR FLUID

The steady three-dimensional stagnation-point flow of an electrically conducting micropolar fluid in the absence and in the presence of a uniform external electromagnetic field (E0,H0) is analyzed and some physical situations are examined. In particular, we proved that if we impress an external magnetic field H0, and we neglect the induced magnetic field, then the steady MHD three-dimensional stagnation-point flow of such a fluid is possible if, and only if, H0 has the direction parallel to one of the axes. In all cases it is shown that the governing nonlinear partial differential equations admit similarity solutions. Moreover in the presence of an external magnetic field H0, it is found that the flow of a micropolar fluid has to satisfy an ordinary differential problem whose solution depend on H0 through the Hartmann number M. Finally, the skin-friction components along the axes are computed