Experimental Investigation Of Relaxation Effect Between Reynolds Stress And Velocity Strain Rate In Turbulent Flow Field Over Wavy Wall With TRPIV

The experimental investigation of wavy wall turbulent flow field in a low speed spill waterchannel with TRPIV. In order to research the influence of turbulence flow forced by the wavywall,the distributions of multiple physical quantities were statistically analyzed.The experimentalinvestigation of complex eddy viscosity model in non-equilibrium wavy wall turbulent boundarylayer was also performed.The time series of instantaneous spatial2D-2C flow fields of turbulent boundary layer overa wavy wall were measured by TRPIV at three different Reynolds numbers with high timeresolution. Thus the statistical quantities were calculated including the mean streamwise andnormal velocities, turbulence intensity. The periodic distributions of the streamwise andwall-normal velocity contours in streamwise direction were found,and near the wall the meanstreamwise and normal velocities were influenced by the wavy wall.Using the quadrantdecomposition evaluate the contribution of four quadrants to the Reynolds shear stressproduction,indicating the ejection event Q2and the sweep event Q4represent the majorcontribution.At the same time the spatial distributions of Reynolds stress and mean velocity strain ratewere obtained by ensemble average，and the distribution of them has a certain regularity.Using thespatial cross-correlation technique, the spatial phase relationship in streamwise direction betweenmean velocity strain rate and Reynolds stress was investigated. It is found that there exist spatialphase differences between Reynolds stress components and mean velocity strain ratecomponents.In the turbulence boundary the phase differences decrease gradually from zero afterleaving the wall and reach minimum value around0.2,then increase gradually.What’s more,theinfluence of the Reynolds numbers to the phase differences is found very small. The reasonabilityof the complex eddy viscosity model is confirmed by these experimental evidences in order toforecast non-equilibrium turbulence accurately.