Turbulent flow over mesh roughness

The surface shear stress, mean velocity, turbulence intensities and Reynolds shear stress have been measured in the boundary layer developing over a mesh type rough surface. The results confirm the conclusions of Perry et al. (1983) that an improved measurement of the Reynolds shear stress in the near-wall region is obtained by increasing the included angle of the X-wire probe from 90 to 120 deg. Direct measurement of the wall shear stress using a floating element also confirm the conclusion of Perry et al. that the value estimated from the Hama defect law is about 20 percent too high. The roughness function Delta-u/u(tau) determined from mean velocity profiles indicates an equivalent sand grain roughness for the mesh surface of about ten times the center line average roughness length.