Effect of Particle Volume Fraction on Turbulence in Pipes and Channels

Abstract

It is well known that turbulent channel and pipe flows show subtle differences in flow statistics. Here we investigate the effect of particle loading on the turbulence in these two geometries. We perform direct numerical simulations of both turbulent channels and pipes at Re τ = 180 with St + = 100 particles. Particle volume fractions of Φ f = 2×10 −5 , 2×10 −6 are compared with unladen simulations. Mean flow and turbulence intensities as well as energy spectra are computed along with visual inspection of Q-criterion iso-surfaces. The findings show that in both pipes and channels turbulence intensity is reduced in the inner region but slightly increased in the outer region. The effect being more pronounced in channels, despite the a larger near-wall accumulation of particles in pipes. Spectral signature shows a shift of energy to longer wavelength and away from the wall.

Particle transport in a turbulent pipe flow: direct numerical simulations, phenomenological modelling and physical mechanisms

“…Further, when point-particle direct numerical simulation (PP-DNS) of pipes (Picano, Sardina & Casciola 2009) is compared with channels (Sardina et al 2012), an augmentation of near-wall particle concentration for pipes is observed. This greater wall accumulation for pipes was directly contrasted by Zahtila et al (2020), suggesting that the two geometric distinguishing features of a pipe, an axisymmetric restriction on centreline and curvature in the solid surface at the wall, are not negligible. A pipe was chosen for this study to maintain intimate connection with the preceding deposition experiments and applied mathematical modelling.…”