Blocking an inviscid shear flow

Abstract

The upstream influence in an inviscid two-dimensional shear flow around a semicircular ‘cape’ (radius A) is computed using a piecewise uniform vorticity model of a boundary-layer current. The area of this layer upstream from the cape increases as the square root of time t when A is small, and increases as t for larger A. Complete blocking occurs when A is approximately three times the boundary-layer thickness, in which case all oncoming particles accumulate in a large upstream vortex. The numerical results obtained from the contour dynamical method also show the generation of large eddies downstream from the obstacle.