Flows and Their Stability in Rotating Cylinders With a Porous Lining

Flow fields in an annulus between two rotating cylinders with a porous lining have been numerically examined in this study. While the outer cylinder is stationary, the inner cylinder is rotating with a constant angular speed. A homogeneous and isotropic porous layer is press-fit to the inner surface of the outer cylinder. The porous sleeve is saturated with the fluid that fills the annulus. The effects of porous sleeve thickness and its properties on the flows and their stability in the annulus are numerically investigated. Three-dimensional momentum equations for the porous and fluid layers are formulated separately and solved simultaneously in terms of velocity and vorticity. The solutions have covered a wide range of the governing parameters (10−5≤Da≤10−2, 2000≤Ta≤5000, 0.8≤b¯≤0.95). The results obtained show that the presence of a porous sleeve generally has a stabilizing effect on the flows in the annulus.

Flow Stability in Rotating Cylinders With a Porous Lining

The effects of porous sleeve properties on the flow stability in rotating cylinders are numerically investigated in this study. To this end, three-dimensional momentum equations for the porous and fluid layers are formulated separately in terms of velocity and vorticity. These equations are then numerically solved over a wide range of parameters (10−2 ≤ Da ≤ 10−5, 2000 ≤ Ta ≤ 5000) to determine the critical Taylor number for the onset of flow instability for various porous sleeve properties. The results obtained show that the presence of a porous sleeve in general has a stabilizing effect on the flow in the annulus.