Hemorheology of dense suspension of red blood cells in a wall-bounded shear flow

We numerically investigate the rheology of a suspension of red blood cells (RBCs) in a wall-bounded shear flow for a wide range of viscosity ratios between the cytoplasm and plasma. The behavior of RBCs, modeled as a biconcave capsule whose membrane follows the Skalak’s constitutive law, is simulated for volume fractions of RBCs up to 0.41 and different Capillary numbers (Ca). Our numerical results show that, an RBC subjected to lower Ca tends to show stable rolling motion with higher intrinsic viscosity, and sifts to the stable swinging or tank-treading motion as increasing Ca, with lower intrinsic viscosity. Hydrodynamic interaction allows the RBCs to deform into swinging or tank-treading like motion, and hence the intrinsic viscosity starts to decreases at a semi-dilute condition, but regains for further higher volume fractions. Because of such mode change from dilute to semi-dilute condition, a polynomial approach of volume fraction for the suspension of RBCs cannot be simply applied.