Aspect ratio and Reynolds number effects on the flow behind a rearward-facing step

Hot Film Velocity Measurements Downstream of a Swept Backward-Facing Step

“…If the AR is too small it is possible that the side walls of the test section could adversely effect the flow over the step. de Brederode and Bradshaw (1972) found that the lower limit for ignoring the effects due to AR was 10, but Ellzey and Berbee (1988) found little or no effect down to values as low as 4. The second parameter, the expansion ratio, is defined as the ratio, relative to the step, of the downstream to upstream cross sectional areas.…”