| In terms of periodic vortex structure of Karman vortex-street stream-wise in cylindrical wake flow, experimental measurement, for spatial relaxation effect between Reynolds stress and mean velocity strain for cylindrical wake flow in low-speed return-flow water trough sink, was made, by virtue of two dimension high time resolution particle image velocimetry (TRPIV) technology. As thus, experimental investigations on complex eddy viscosity modeling of cylindrical wake flow were carried out.Cylindrical wake flow in different Reynolds number can be acquired through cylindrical models in different diameters put in a water trough sink. The time sequence signals of spatially distributed image of two-dimension instantaneous velocity in cylinder wake can be got by virtue of TRPIV technology. Further, the spatial distribution of two dimension instantaneous velocity gradient and velocity strain can be known in the way of spatial difference. Then, the spatially distributed image of average velocity strain can be acquired through time average.At the same time, the spatial distribution of two dimension average velocity can be got by time average on the time sequence of the spatial distribution of two dimension fluctuation velocity. Moreover, instantaneous fluctuation velocity minus average velocity results in the time sequence of the spatial distribution of fluctuation velocity. Then, the time sequence of the product-spatial distribution of different fluctuation velocity component is made by time average. At last, the spatial distribution of two dimension every Reynolds-stress component can be acquired.The rationality of the theory on eddy viscosity model for turbulent flow will be verified, by virtue of phase share comparison between the phase of the spatial distribution of Reynolds-stress and the phase of the spatial distribution of average velocity strain, in terms of the theory on eddy viscosity model for turbulent flow.
|
PDF Full Text Request