Simulations of sheared dense noncolloidal suspensions: Evaluation of the role of long-range hydrodynamics
Résumé
This work intends to evaluate the role of many-body long-range hydrodynamics by simulations of sheared neutrally-buoyant non-Brownian, non-colloidal suspensions. Three-dimensional simulations of sheared suspensions are conducted with and without long-range hydrodynamics, for a volume fraction range between 0.1 to 0.62 (frictionless) and 0.1 to 0.56 (frictional). Discarding long-range hydrodynamics has only a moderate effect on viscosity for the range of volume fractions investigated and viscosities diverge with similar scaling laws ; the critical fraction is found to be approximately 0.64 (frictionless) and 0.58 (frictional). Conversely, many-body hydrodynamics are found to affect diffusion and particle velocities, which are correlated on a longer range when long-range interactions are included, even in dense suspensions. This means that long-range hydro-dynamics may not be significantly screened by crowding. Assuming only short-range lubrication interactions is therefore suitable for predicting viscosity in non-colloidal suspensions but becomes questionable when flow details (e.g., diffusion or velocity correlations) are needed.
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