Eddy Formation behind Circular Cylinders

Explanations of how and why eddies form in the wake of a cylinder in cross-flow are offered. Potential flow theory is used to demonstrate basic tendencies resulting from the behavior of shear layers and vortices under a variety of conditions prevailing in actual flows. Eddies shed alternately behind a cylinder and form Karman vortex streets, as a combination of vorticity emanating from the boundary layers and the instability of these layers due to the vorticity which they contain. Potential flow theory modeling gives useful predictions of flow about bluff cylinders. Shear layers are readily disintegrated by flow disturbances. The effects of vorticity in boundary layers on other regions apparently can be approximated by the effects of distributed finite vortices in the potential theory modeling of flow about cylinders.