Nonequilibrium characteristics and spatiotemporal long-range correlations in dense gas-solid suspensions

Abstract The nonequilibrium properties and strong spatiotemporal long-range correlations in gas-solid suspensions were analyzed systematically by discrete particle simulation in periodic domains. The effective interphase slip velocity is significantly larger than the particle terminal velocity, the particle velocity distribution function is non-Maxwellian with a high-energy tail and the solid concentration distribution function is far from the discrete Poisson distribution, all of which manifest strong deviation from the equilibrium or homogeneous state in gas-solid flow. The solid concentration, gas and solid velocities are spatiotemporally correlated and show a clear scale-dependence. More importantly, all characteristic correlation lengths scale linearly with the size of simulation domain, although the correlation length of solid concentration is much smaller than those of gas and solid velocities. On the other hand, the characteristic correlation times at first increase with increasing domain size and then seem to approach to asymptotic values. Those results indicate that the heterogeneity and spatiotemporal long-range correlations should be considered properly in continuum theory of heterogeneous gas-solid flow.