Effect of Permeability on the Rheology of Non-Brownian Suspensions over Porous Media Models*

We comprehensively investigate the effects of different permeability and porosity of porous media models on the rheological properties of shear flow suspension of non-colloidal particles with particle volume fractions ranging from 0 to 40% using a rheometer. We have precisely designed two different porous media models to examine the impact of porous surfaces on suspension flows. In particular, one model allows the suspension particles to move through the porous layer while the other one restricts them. We observed the shear thinning behavior of suspensions over permeable surfaces for concentrations above 15% for both models. We then analyzed the slip velocity and slip length for different suspension concentrations over both porous models. While the slip velocity where particles do not move inside the porous layer shows higher value, for both models the slip length first decreases for concentrations up to 15%, then increases for 30% and 40%. Comparing the experimentally obtained slip velocity data with the theory of shear flow over porous media, we found a good agreement for the case where particles are not able to move inside the porous layer. This also shows that the theoretical model which is based on Newtonian fluid, can also be used for suspensions. 

Funding: National Science Foundation award #1854376