Hall effects on the unsteady Couette flow between two infinite horizontal parallel plates in a rotating system under the boundary layer approximations have been studied. One of the plate is at rest and the other oscillates in its own plane with the velocity U(t). An exact solution of the governing equations has been obtained by the use of the Laplace transform technique. The numerical results for the velocity components and the shear stresses are depicted graphically. Asymptotic behavior of the solution has analyzed for large values of magnetic parameter, rotation parameter and frequency parameter to gain some physical insight into the flow pattern. It is observed that there exists thin boundary layer (s) is formed near the stationary plate for large values of rotation parameter, magnetic parameter and frequency parameter.

The unsteady hydromagnetic flow of a viscous incompressible electrically conducting fluid between two parallel disks rotating with the same angular velocity initially about non-coincident axes, which are suddenly made coincident, has been studied. An analytical solution describing the flow at large and small times after the start is obtained by the use of Laplace transform technique. The physical interpretations for the emerging parameters are discussed with the help of graphs. The shear stresses obtained from the general solution and from the solution for small time are compared.