Membrane model and energetics
The computational model for the red blood cell (RBC) membrane is presented in this chapter. Based on the discussions in section 4.2, it is assumed that an undeformed RBC is stress-free and that this equilibrium shape does not change in time. The membrane model is formulated in such a way that any deviation from the equilibrium shape increases the membrane energy and response forces are induced which drive the membrane shape towards its equilibrium. The equilibrium shape itself can be chosen arbitrarily if other deformable particles shall be studied. In particular, the RBC membrane may be replaced by spherical, ellipsoidal, or more complex shapes.