A contribution to the free-stream turbulence effect on the flow past a circular cylinder

The effect of the free-stream turbulence on the flow past a circular cylinder was studied experimentally in the subcritical and critical regimes. Several grids were used to produce approximately homogeneous turbulent fields with longitudinal integral scales ranging from 0·30 to 3·65 cylinder diameters and with the longitudinal intensities ranging from 1·4 to 18·5%.The critical Reynolds number Rc at which the time-mean drag coefficient obtains the value of 0·8 was found to satisfy the relation Rc1·34 T = 1·98 × 105, where T is the Taylor number defined in terms of the longitudinal integral scale. The time-mean drag coefficient, the base-pressure coefficient and the spanwise correlation length of the surface-pressure fluctuations in the vicinity of the separation point were fairly well correlated with the parameter R1·34T, R being the Reynolds number. It was argued that the parameter R1·34T will control some aspects of the flow past a circular cylinder immersed in turbulent streams.