Near-surface particle image velocimetry measurements in a transitionally rough-wall atmospheric boundary layer

Abstract

The Reynolds number dependence of the structure and statistics of wall-layer turbulence remains an open topic of research. This issue is considered in the present work using two-component planar particle image velocimetry (PIV) measurements acquired at the Surface Layer Turbulence and Environmental Science Test (SLTEST) facility in western Utah. The Reynolds number (δuτ/ν) was of the order 106. The surface was flat with an equivalent sand grain roughness k+ =18. The domain of the measurements was 500 < yuτ/ν. <3000 in viscous units, 0.00081 < y/δ <0.005 in outer units, with a streamwise extent of 6000 ν/uτ. The mean velocity was fitted by a logarithmic equation with a von Káarmán constant of..