2026/06/09 by Ananthapadmanabhan Ramesh, Abbas Moradi Bilondi, Mohammadreza Mahmoudian +1
Engineering · #Heat and Mass Transfer in Porous Media #Particle Dynamics in Fluid Flows #Granular flow and fluidized beds
paper · pdf · doi:10.1017/jfm.2026.11783
The current study presents a three-dimensional linear stability analysis of particle-laden Couette-Poiseuille flow (CPF) suspended in a Newtonian fluid between two parallel plates, with the lower plate coated by a porous medium. The influence of suspended particles is examined using a two-domain formulation in which particles are confined to the fluid layer and do not penetrate the porous substrate. The particle-laden suspension is modelled using the dusty gas framework, while the flow within the porous layer is described by the volume-averaged Navier–Stokes equations. In particle-laden flows over impermeable walls, particle inertia may either stabilise or destabilise the flow depending on the governing parameters. In contrast, the presence of a porous layer introduces an additional permeability-dependent destabilising mechanism that fundamentally modifies these classical trends. Consequently, particle loading can reduce the critical Reynolds number at sufficiently high permeability, even in parameter regimes where particles stabilise the corresponding rigid-wall flow. The coupled formulation also introduces additional disturbance branches associated with fluid–particle coupling near the permeable interface. Although these modes remain stable throughout the parameter space investigated, they modify the eigenspectrum and influence the dominant instability through altered coupling pathways. Furthermore, unlike impermeable-wall CPF, where increasing the Couette component generally stabilises the flow, the porous-wall configuration exhibits a monotonic decrease in the critical Reynolds number over the range examined. These results demonstrate that porous boundaries can fundamentally alter established stability behaviour in particle-laden shear flows through permeability-dependent coupling between the suspension and the porous substrate.