Backflow events under the effect of secondary flow of Prandtl's first kind

Abstract

A study of the backflow events in the flow through a toroidal pipe at friction Reynolds number Reτ ≈ 650 is performed and compared with the results in a straight turbulent pipe flow at Reτ ≈ 500. The statistics and topological properties of the backflow events are analysed and discussed. Conditionally averaged flow fields in the vicinity of the backflow event are obtained, and the results for the torus show a similar streamwise wall-shear stress topology which varies considerably for the azimuthal wall-shear stress when compared to the pipe flow. In the region around the backflow events, critical points are observed. The comparison between the toroidal pipe and its straight counterpart also ..