Instability of a Particle-laden Couette-Poiseuille flow overlying a porous medium

The current study focuses on stability analysis of particle-laden Poiseuille-Couette flow of a Newtonian fluid between two parallel plates in which the bottom one is coated with a porous medium. A linear stability analysis is performed based on a two domain approach where the flow in the porous layer is considered separately from that in the channel. The dusty gas model is used to simulate the flow dynamics of both pure fluids and particles coupled with the Volume-Average Navier-Stokes equation for the porous medium. Different studies were performed to analyze the impact of the Couette flow component, particle mass fraction, and permeability parameter (ratio of fluid layer thickness to the square root of permeability) on the stability. Results reveal a bimodal neutral curve, indicating the competition between porous-layer and fluid-layer modes. However, increase of the Couette flow component leads to the dominance of the fluid-layer mode over the porous-layer mode, resulting in a unimodal neutral curve. Further, the critical Reynolds number increases with a higher value of the permeability parameter, even in the presence of Couette flow. Moreover, at a high permeability parameter, an increase in the particle mass fraction leads to a stabilizing effect on the flow. It’s envisioned that the current work will help in stabilizing the flow with particles by varying the Couette component and physical properties of the porous layer.