The phenomenon of blocking in stratified flows

Abstract

The phenomenon of blocking in stratified inviscid flows over an obstacle is characterized by the occurrence of stagnant zones separated from the flow region by lines of velocity discontinuity. The stagnant zone occurs in front of and is caused by the obstacle. In this paper, it is shown that the mathematical solution for flows with a stagnant layer involves the solution of a free streamline problem, the free streamline being the line of velocity discontinuity. An inverse method is used to obtain an exact solution to the problem. The parameter governing the flow is a modified Froude number. It is found that at low Froude number, the height of the stagnant zone is the same as the height of the obstacle, but as the Froude number increases, the stagnant zones have been found to decrease for wedge-shaped obstacles. Large-amplitude lee waves behind the obtacle are also found, as well as downstream eddies.