  We study the deformation and motion of an erythrocyte in fluid flows via a
lattice Boltzmann method. To this purpose, the bending rigidity and the elastic
modulus of isotropic dilation are introduced and incorporated with the lattice
Boltzmann simulation, and the membrane-flow interactions on both sides of the
membrane are carefully examined. We find that the static biconcave shape of an
erythrocyte is quite stable and can effectively resist the pathological changes
on their membrane. Further, our simulation results show that in shear flow, the
erythrocyte will be highly flattened and undergo tank tread-like motion. This
phenomenon has been observed by experiment very long time ago, but it has
feazed the boundary integral and singularity methods up to the present. Because
of its intrinsically parallel dynamics, this lattice Boltzmann method is
expected to find wide applications for both single and multi-vesicles
suspension as well as complex open membranes in various fluid flows for a wide
range of Reynolds numbers.
