Transport of blood cells studied with fully resolved models

Blood is an important fluid for the human body. It exhibits a complex behavior in terms of rheology and cell transport which arises mainly from the high concentration of the deformable red blood cells (RBCs). Due to this property, blood can be approximated as a dense suspension of RBCs immersed in a Newtonian fluid, the blood plasma. The present work focuses on the transport of blood cells with fully resolved models. This has a dual nature: on the one hand to look into the methods used for blood modeling, and on the other to apply these models in the transport of RBCs and platelets. Two models are employed, one in two-dimensions and one in three-dimensions, both based on the combined Immersed boundary-Lattice Boltzmann method (IB-LBM). The 2D model recovers shear thinning, the formation of a cell-free layer and the margination of platelets. Following its validation, simulations in aneurysmal geometries highlighted a region of high hematocrit very close to the aneurysmal wall, indicating a cell-distribution relevant to the formation of a thrombus or to the wall weakening of an aneurysm. The shear-induced diffusion of RBC- and platelet-like particles exhibits a non-linear scaling with respect to shear-rate. A parallel 3D implementation is also described, demonstrating fairly good weak and strong scaling performance, and was used on a seemingly simple but challenging benchmarks to illustrate the effect of a number of IB-LBM parameters.