Three-Dimensional Flow Pattern Upstream of a Surface-Mounted Rectangular Obstruction

Abstract

A three-dimensional TEACH-like computer code is developed and employed to study the flow phenomena upstream of a rectangular obstruction placed in a two-dimensional turbulent boundary layer. Satisfactory comparison is obtained with the experimental results of Blair (1984, 1987). The general trends, regarding the dependence of vortex dimensions, wall static pressure distributions and saddle point positions on Re = U∞ δ*/ν and on D* = D/δ*, are similar to the experimental results for circular cylinders (Eckerle and Langston, 1986 and Baker, 1980). The position of the saddle point depends on the turbulence intensity in the primary vortex. The pressure coefficient at the foot of the obstruction depends solely on D* if no corner vortex exists. This coefficient is reduced when a corner vortex is present. All the computed flow patterns are similar to the one-vortex model of Eckerle and Langston (1986). The four-vortex model reported by Baker (1980) and Hunt et al. (1978) cannot be found in any of the calculations.