Numerical simulation of particle-laden turbulent channel flow

Abstract

This paper presents results for the behavior of particle-laden gases in a small Reynolds number vertical channel down flow. Results will be presented for the effects of particle feedback on the gas-phase turbulence and for the concentration profile of the particles. The effects of density ratio, mass loading, and particle inertia will be discussed. The results were obtained from a numerical simulation that included the effects of particle feedback on the gas phase and particle-particle collisions. The resolution of the simulation was comparable to the smallest scales in the particle-free flow, but the grid spacings were larger than the particle size. Particle mass loadings up to 2 and both elastic and inelastic collisions were considered. Particle feedback causes the turbulent intensities to become more anisotropic as the particle loading is increased. For small mass loadings, the particles cause an increase in the gas flow rate. It will be shown that the particles tend to increase the characteristic length scales of the fluctuations in the streamwise component of velocity and that this reduces the transfer of turbulent energy between the streamwise component of velocity and the components transverse to the flow. Particle-particle collisions greatly reduce the tendency of particles to accumulate at the wall for the range of mass loadings considered. This was true even when the collisions were inelastic.

Turbulence attenuation in particle-laden flow in smooth and rough channels

“…It is well known that small heavy particles with large Stokes number dampen turbulence (Tsuji, Morikawa & Shiomi 1984;Gore & Crowe 1989;Hetseroni 1989;Elghobashi & Truesdell 1993;Kulick, Fessler & Eaton 1994;Li et al 2001;Yamamoto et al 2001;Ferrante & Elghobashi 2003;Mito & Hanratty 2006;Vreman 2007). In their experiments on particle-laden plane channel flow, Kulick et al (1994) reported a strong attenuation of the air turbulence intensity at low solid volume fraction but significant solid mass loading.…”

“…Thus, if p-w collisions are included, it seems appropriate to include also p-p collisions in simulations of this type, although the overall particle volume fraction is low. Others have shown that p-p collisions significantly flatten the mean particle velocity profile and the mean particle volume fraction velocity profile at low volume fractions (Li et al 2001;Yamamoto et al 2001;Vreman 2007;Nasr et al 2009). At larger volume fractions p-p collisions were shown to enhance the transfer from the kinetic energy in the streamwise particle velocity fluctuations to the kinetic energy in both the normal and spanwise particle velocity fluctuations (Vreman et al 2009).…”

“…It is often mentioned that inter-particle collisions are negligible if the volume fraction is smaller than 10 or even lower (Li et al 2001;Yamamoto et al 2001;Vreman 2007;Nasr et al 2009). These references show that collisions reduce the tendency of preferential concentration of particles.…”

“…PP-DNS studies of vertical downward particle-laden plane channel flow in the literature were hitherto limited to lower Reynolds number: Re τ = 180 with one-way coupling (Rouson & Eaton 2001), Re τ = 210 with two-way coupling (Kubik & Kleiser 2006), and Re τ = 125 (Li et al 2001) and Re τ = 150 (Mito & Hanratty 2006) with two-way coupling and inter-particle collisions. If we include PP-DNS of horizontal or non-gravitational particle-laden plane channel flows in our discussion, one-way coupled simulations of such flows were (for example) performed at Re τ = 150 (Pedinotti, Mariotti & Banerjee 1992;Marchioli & Soldati 2002), Re τ = 300 (Lavezzo et al 2010) and Re τ = 950 (Geurts & Kuerten 2012;Kuerten & Brouwers 2013), two-way coupled simulations up to Re τ = 395 (Kuerten, van der Geld & Geurts 2011;Zhao, Andersson & Gillissen 2013) and two-way coupled simulations with inter-particle collisions at Re τ = 125 (Nasr, Ahmadi & McLaughlin 2009).…”

“…The experimental work of Kulick et al (1994), hereafter referred to as KFE1994, has frequently been used for comparison with results of numerical simulations of vertical (downward) particle-laden channel flows (Wang & Squires 1996;Li et al 2001;Rouson & Eaton 2001;Yamamoto et al 2001;Segura 2004;Kubik & Kleiser 2006). In all these simulations the Eulerian-Lagrangian method was used.…”