A fast finite difference method is proposed to solve the incompressible
Navier-Stokes equations defined on a general domain. The method is based
on the voricity stream-function formulation and a fast Poisson solver defined
on a general domain using the immersed interface method. The key to the new
method is the fast Poisson solver for general domains and the interpolation
scheme for the boundary condition of the stream function. Numerical examples
thats show second order accuracy of the computed solution are also provided.