DPIV study of the turbulent boundary layer over V-shaped cavities

摘要

In the present work the digital particle image velocimetry technique (DPIV) is used to study the turbulent boundary layer over a surface made up of V-shaped cavities placed transversely to the flow direction. The integral measures of the boundary layer like the displacement and momentum thickness are estimated from the mean velocity field. The wall shear-stress is higher than the corresponding smooth surface values. From the fluctuating velocity field it is observed maximum turbulence levels in the region just above the cavities. Study of coherent turbulent structures suggests the presence of strong outflows of fluid from the cavities as well as inflows into the cavities. It is conjectured that the mass transfer/exchange between cavities and main stream, play an important role in the high levels of turbulent energy observed.