Flow is left to right with jet axis along lower boundary.
Contours of constant vorticity in an incompressible free shear layer. Flow is left to right. Motion shows roll-up of layer into vortex street and subsequent pairing of adjacent vortices. The motion of fluids holds both aesthetic and practical fascination for humans. With the advent of the digital computer, numerical simulation joined theory and experiment in the arsenal of scientific techniques that can be brought to bear in unraveling the mysteries of fluid flow.