PNNL

Abstract

Cellular suspensions such as blood are a part of living organisms and their rheological and ?ow characteristics determine and affect majority of vital functions. The rheological and ?ow properties of cell suspensions are determined by collective dynamics of cells, their structure or arrangement, cell properties and interactions. We study these relations for blood in silico using a mesoscopic particle-based method and two different models (multi-scale/low-dimensional) of red blood cells. The models yield accurate quantitative predictions of the dependence of blood viscosity on shear rate and hematocrit. We explicitly model cell aggregation interactions and demonstrate the formation of reversible rouleaux structures resulting in a tremendous increase of blood viscosity at low shear rates and yield stress, in agreement with experiments. The non-Newtonian behavior of such cell suspensions (e.g., shear thinning, yield stress) is analyzed and related to the suspension’s microstructure, deformation and dynamics of single cells. We provide the ?rst quantitative estimates of normal stress differences and magnitude of aggregation forces in blood. Finally, the ?exibility of the cell models allows them to be employed for quantitative analysis of a much wider class of complex ?uids including cell, capsule, and vesicle suspensions.