Abstract
Direct numerical simulations are presented for pressure-driven and simple shear channel flow of cell suspensions. The presence, motion, and deformation of cells are accounted for on the basis of the immersed interface method. Deformable microparticles are also included to model blood contained or pharmaceutical particles. The study focuses on the effects of channel height on the hydrodynamic diffusion characteristics of the contained particles. Although such effects are rather expected to be significant, they have not been systematically considered in the literature. The proximity with the bounding walls affects the mobility of the particles, even more so due to the low-Reynolds-number prevailing conditions. For pressure-driven flow the diffusivities increase with distance from the wall due to the increasing mobility and reach a channel-size-dependent maximum due to the diminishing local shear rate. Near the channel center, where the mean shear rates vanish, diffusivities remain finite owing to convection from cross-flow sweeps generated from the interaction of eddies formed in the opposing walls. It is suggested that the hydrodynamic mobility and its dependence on distance from the walls should be added to factors affecting the diffusivities, such as the local shear rate and the cell volume fraction and elasticity.
8 More- Received 2 July 2019
DOI:https://doi.org/10.1103/PhysRevFluids.4.113103
©2019 American Physical Society