Shape changes and motion of a vesicle in a fluid using a lattice Boltzmann model

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.