Effect on turbulence production due to sudden change in flow regimes

Flow regimes were investigated in the cavity formed between the roughness elements in a laboratory water flume. Further tests were carried out on similar aspect ratio of the cavity to study the effect on turbulence production because of change in local bed geometry. The idealized 2-D bed roughness has been aligned perpendicular to the flow direction, and velocity measurements were made using a laser Doppler velocimeter. Skimming and transition regime has been identified between the roughness elements with the help of flow visualization. Turbulence production was investigated at test section with and without the presence of urban approach roughness. The effect on turbulence production in the boundary layer was significantly influenced by the upstream roughness and height of the roughness element.