Fully resolved numerical simulation of turbulent pipe flows laden with large neutrally-buoyant particles

In this article, we employ a fully-resolved numerical simulation method (the fictitious domain method) to investigate the effects of large neutrally-buoyant particles on the turbulent flow in a pipe at low Reynolds number and non-dilute regimes. The tube Reynolds number is fixed to be 4 900, the particle-pipe diameter ratio is 0.1, and the particle volume fraction ranges from 0.33% to 10%. Our results indicate that the presence of large particles decreases the maximum root-of-mean-square (rms) of the streamwise velocity fluctuation near the wall by weakening the intensity of large-scale streamwise vortices, although in the region very close to the wall the particles increase the rms of streamwise velocity fluctuation. On the other hand, the particles induce small-scale vortices in the near-wall region, resulting in the enhancement of the rms of radial and circumferential velocity fluctuations there.