We present a new methodology for the numerical resolution of the hydrodynam
ics of incompressible viscid newtonian fluids. It is based on the Navier-St
okes equations and we refer to it as the vorticity projection method. The m
ethod is robust enough to handle complex and convoluted configurations typi
cal to the motion of biological structures in viscous fluids. Although the
method is applicable to three dimensions, we address here in detail only th
e two dimensional case. We provide numerical data for some test cases to wh
ich we apply the computational scheme.