  The nature of blood as a suspension of red blood cells makes computational
hemodynamics a demanding task. Our coarse-grained blood model, which builds on
a lattice Boltzmann method for soft particle suspensions, enables the study of
the collective behavior of the order of 10^6 cells in suspension. After
demonstrating the viscosity measurement in Kolmogorov flow, we focus on the
statistical analysis of the cell orientation and rotation in Couette flow. We
quantify the average inclination with respect to the flow and the nematic order
as a function of shear rate and hematocrit. We further record the distribution
of rotation periods around the vorticity direction and find a pronounced peak
in the vicinity of the theoretical value for free model cells even though
cell-cell interactions manifest themselves in a substantial width of the
distribution.
