Alireza Khodabakhshi and Bernhard Vowinckel: Influence of Wall Boundaries on the Transition Between the Viscous and Inertial Regimes in Suspensions

Using particle-resolved Direct Numerical Simulations (pr-DNS), we study the rheology of dense suspensions in a confined volume-imposed cell. We reproduce the general trend of the viscous–inertial transition observed in recent experiments and capture the weakening of the effective friction coefficient along the transition. By varying the wall roughness and confinement, we show that wall boundaries strongly influence bulk stress values by controlling particle layering and inter-layer mixing at the microscale, while the overall viscous–inertial transition trend remains consistent.