Influence of Ridge Spacing, Ridge Width, and Reynolds Number on Secondary Currents in Turbulent Channel Flow Over Triangular Ridges

Abstract Most studies of secondary currents (SCs) over streamwise aligned ridges have been performed for rectangular ridge cross-sections. In this study, above triangular are systematically studied using direct numerical simulations turbulent channel flow. The influence spacing on flow topology, mean flow, and turbulence statistics is investigated at two friction Reynolds numbers, 550 1000. addition, the effects width SCs, which not previously considered shape, explored. SCs shear stress increases with increased until fill entire channel. One primary findings that, configurations pronounced currents, exhibit clear number sensitivity a significant growth dispersive levels number. contrast to ridges, no above-ridge tertiary flows observed tested range widths. Flow visualisations reveal existence corner vortices that form intersection lateral sides smooth-wall sections. These found gradually disappear as increase in width. Premultiplied spectra velocity fluctuations show strong dependency spanwise sampling location. Whereas averaged modifications by energy emerges higher wavelengths sampled locations correspond centres currents.