Reynolds number and roughness effects on turbulent stresses in sandpaper roughness boundary layers

Abstract

Multicomponent turbulence measurements in rough-wall boundary layers are presented and compared to smooth-wall data over a large friction Reynolds number range (δ+). The rough-wall experiments used the same continuous sandpaper sheet as in the study of Squire et al. [J. Fluid Mech. 795, 210 (2016)JFLSA70022-112010.1017/jfm.2016.196]. To the authors' knowledge, the present measurements are unique in that they cover nearly an order of magnitude in Reynolds number (δ+≃2800-17400), while spanning the transitionally to fully rough regimes (equivalent sand-grain-roughness range, ks+≃37-98), and in doing so also maintain very good spatial resolution. Distinct from previous studies, the inner-normal..