Abstract: The 3D incompressible Navier-Stokes equation was solved numerically to simulate the wake development and the ground vortex formation caused by a rotor in forward flight near the ground The characteristics of the ground vortex and the distribution of the induced velocity at rotor disc were studied and their influences by advance ratio were investigated To avoid directly simulate rotor blades with non-orthogonal curvilinear coordinates, momentum sources were added to the Navier-Stokes equation to imitat...