Cell swarming leads to vortex flow in early embryo formation

A forming embryo can be though of as a confined region of incompressible medium. Vortex flow is observed in early embryo formation from \em drosophila \em fruit flies to mammals. The Navier-Stokes equation for fluid flow in a cavity is known to have stable vortex solutions. A model for cell motion in which cells move independently of their neighbors corresponds to high Reynolds number (\em Re\em) incompressible flow. An alternative cell-swarming model in which cells do influence their neighbors motion (through a mechanism known as \em contact following\em) corresponds to a flow model that is similar to low \em Re \em incompressible flow. Both models can potentially lead to stable vortex formation in a confined cavity. We investigate the applicability of both models to real biological systems