抄録
Flow visualization and multi-point simultaneous hot-wire measurements were made to study organized structures vicinity of roughness elements for the boundary layer over a k-type rough wall. Vortex structure in a groove is seemingly unsteady three-dimensional over a k-type rough wall but seemingly steady two-dimensional over a d-type rough wall. Frequency, duration and spanwise spatial scale were investigated and compared for inflows and outflows observed in the flow visualization and for ejections and sweeps detected in the hot-wire measurement.
