Effect of span-wise variation in a two-dimensional obstacle on flow development downstream

Tests were performed in an open wind tunnel to study the effects of spanwise variations (in the form of castellations) in a barrier on the development of downstream flow. The spanwise variations are found to lead to local nonuniformities, which travel at first sideways and upward. However, as the boundary layer grows, the nonuniformities quickly localize and propagate downward, and finally reach the very lowest layers, where they appear to become entrapped.