Turbulence production and transport in quasi-two-dimensional wake/boundary-layer interaction

The turbulent kinetic energy aspects related to production and transport in the wake of a cylinder interacting with a boundary layer have been investi gated experimentally. Using a simple but efficient technique, the velocity power spectral characteristics in the intermediate wake were modified to co mply with the requirements for quasi-two-dimensional behavior, i.e., to dis play a scaling region deviating from the -5/3 power law, which is typical o f homogeneous, three-dimensional turbulence. The cylinder was placed parall el to the plate and normal to the flow, with its wake developing just outsi de of the boundary layer but with its lower part in contact and interacting with it. The streamwise and normal-to-the-plate velocity components have b een recorded simultaneously in the intermediate wake using hot-wire anemome try. In addition to the calculation of kinetic energy production, third-ord er correlations of the two velocity fluctuation components, denoting stream wise and lateral transport of the corresponding kinetic energy terms, have also been evaluated. There is significant reduction of kinetic energy produ ction in the lower half wake, in contact with the boundary-layer, as compar ed to the upper half on the freestream side. This is associated with a cons iderable buildup of kinetic energy production within the boundary- layer fl ow. The transport mechanisms in the present how have been investigated and are discussed to provide a basis for formulation and refinement of numerica l models and methodologies.