The Effect of Momentum Transfer Coefficients on Turbulent Suspension Flow over porous media*

We discuss the flow of turbulent suspensions of non-Brownian, non-colloidal, rigid spherical particles in a Newtonian fluid over a porous surface. In this study, we report the effect of the

momentum transfer coefficient τ on the turbulence statistics of suspension flows where the bulk particle volume fraction ranges from 0 to 0.2 for different wall porous permeability, while the thickness and porosity of the porous wall are fixed. We study three values of τ, i.e., −1, 0 and 1, because the momentum transfer coefficient τ of most of the porous media falls in this range that measures the transfer of stress at the porous/fluid interface and depends on the porous material and the texture of the solid interface. Direct numerical simulations (DNS) with an immersed boundary method (IBM) are employed to resolve the particles and flow phase where they coupled with the volume-averaged Navier-Stokes (VANS) to solve the flow within the porous layer. By changing τ from 0 to either 1 or -1 the velocity at the interface between the porous wall and the free fluid region increases significantly. The overall drag is found to grow by changing τ from 0 to 1 and -1 whereas the mean momentum balance analysis shows that the particle-induced stresses are the main factor for the overall drag increase for non-zero τ.