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 investigated experimentally. Using a simple but efficient technique, the velocity power spectral characteristics in the intermediate wake were modified to comply with the requirements for quasi-two-dimensional behavior, i.e., to display a scaling region deviating from the -5/3 power law, which is typical of homogeneous, three-dimensional turbulence. The cylinder was placed parallel to the plate and normal to the flow, with its wake developing just outside 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 been recorded simultaneously in the intermediate wake using hot-wire anemometry. In addition to the calculation of kinetic energy production, third-order correlations of the two velocity fluctuation components, denoting streamwise and lateral transport of the corresponding kinetic energy terms, have also been evaluated. There is significant reduction of kinetic energy production in the lower half wake, in contact with the boundary-layer, as compared to the upper half on the freestream side. This is associated with a considerable buildup of kinetic energy production within the boundary- layer flow. The transport mechanisms in the present how have been investigated and are discussed to provide a basis for formulation and refinement of numerical models and methodologies.