A turbulence dissipation inhomogeneity scaling in the wake of two side-by-side square prisms

We experimentally study how the turbulent energy dissipation rate scales in the cross-stream direction of turbulent wake flows generated by two side-by-side square prisms. We consider three different such turbulent flows with gap ratios G/H = 1.25, 2.4 and 3.5, where G is the distance between the prisms and H is the prism width. These three flows have a very different dynamics, inhomogeneities and large-scale features. The measurements were taken with a multi-camera particle image velocimetry system at several streamwise locations between 2.5H and 20H downstream of the prisms. After removing the large-scale most energetic coherent structures, the normalised turbulence dissipation coefficient C'(epsilon) of the remaining incoherent turbulence is found to scale as C'(epsilon) similar to (root Re-L/Re'(lambda))(3/2) along the highly inhomogeneous cross-stream direction for all streamwise locations tested in all three flows and for all three inlet Reynolds numbers considered; Re'(lambda) and Re-L are, respectively, a Taylor length-based and an integral length-based Reynolds number of the remaining incoherent turbulence.

Automated summary

The study experimentally investigated the scaling of turbulent energy dissipation rate in the cross-stream direction of turbulent wake flows generated by two side-by-side square prisms. The results showed that the normalised turbulence dissipation coefficient for residual incoherent turbulence scaled similarly along the cross-stream direction after removal of large-scale coherent structures.