Structure of conical vortices related with suction fluctuation on a flat roof in oblique smooth and turbulent flows

Abstract A structure of conical vortices on a flat roof in oblique flow is investigated by hot-wire velocity measurements in smooth and turbulent flows. The vortices are stronger in smooth flow than in turbulent flow. The centerlines of the vortices go along the line inclined 13° in the smooth flow and 10° in the turbulent flow relative to the eaves. These lines match the ridge lines of the maximum suction. The lateral component of upstream fluctuating velocity correlates well with the fluctuating suction on the roof both in the smooth and the turbulent flows. The large correlation zones spread toward the downstream along the lines inclined 23–25° to the eaves which are located near the edge of the conical vortices. The distinct feature of the correlation is caused by the alternative growth and decay of each vortex.