Low Reynolds number turbulent swirling pipe flows

Abstract

A direct numerical simulation of a swirling pipe flow is performed to investigate the effects of swirl on turbulence statistics. The swirling motion is imposed via a constant azimuthal body force coupled with a body force in the axial direction that drives the flow. The friction Reynolds number Reτ ≈ 170 with a pipe length of 8πδ (where δ is the pipe radius). The simulations are performed at two swirl numbers S = 0.01 and 0.13. At the lower swirl number, the mean statistics appear to collapse well with non-swirling pipe flows. At the higher swirl number, the axial, radial and azimuthal turbulence intensities show a higher value in the outer region, whereas the axial turbulence intensity decr..