An experimental study of the interaction between grid-generated turbulence and a 2-dimensional bluff body. Effect of the shedding vortices on the upstream turbulence

The interaction between grid-generated turbulent flow and a 2-dimensional circular cylinder is investigated experimentally. Particularly, the effect of the velocity fluctuations induced by the cylinder wake on the upstream turbulent field is quantitatively estimated and the spatial region where the wake vortices affect the upstream turbulence is determined. The fundamental characteristics of the grid turbulence and the pressure distributions on the cylinder surface are first investigated, then measurements of the turbulent velocity tangential to the mean stream line are carefully made by a single hot wire probe mainly in the upstream region of the cylinders. The effect of the wake-induced fluctuation appears in the spatial region upstream at a distance of more than 5 times the radius of the circular cylinder. This effect is largest near the separation point and is smaller on the stagnation line as compared with the effect in the other region. (author)