Particle-laden gas flow in horizontal channels with collision effects

Abstract

A model is presented for the behavior of solid particles in a turbulent horizontal channel flow. Eulerian equations are used in the calculations for the fluid and the polydisperse solid phase. Inter-particle collisions are taken into account that includes two mechanisms: collisions with sliding friction and collisions without sliding friction. Particulate collisions are accounted for by taking into account the collisions due to the difference in the average motion of the various fractions and, also, by the collision due to the particle fluctuating motion caused by the gas turbulence. In addition to the closure equations for the mass and momentum conservation, based on inter-particle collision, this model incorporates an original description of the particle motion in a horizontal channel, by introducing the decomposition of the particle-phase motion into two particle-phase flows: falling and rebounding particle flows. This allows the proper calculation of the wall influence on the particles' motion by accounting for the long-range disturbances of the transverse velocity of the rebounding particles, which are computed with the help of the restitution coefficients. The model has been validated by comparison with the experimental data of Tsuji and Morikawa [Y. Tsuji, Y. Morikawa, LDV measurements of an air-solid two-phase flow in a horizontal pipe. J. Fluid Mech., 120 (1982) 385–409.] for loading ratios up to 50 conveyed by low magnitude gas-phase velocity of 6 to 15 m/s and with the experimental data of Laats and Mulgi [M. Laats, A. Mulgi, Experimental study of the kinematic process of the motion of small solid particles in turbulent flow in the pipe. Proc. 3-rd all-union conference on theoretical and applied issues in turbulent flows (II part). Turbulent Two-phase Flows, Tallinn, ed. Estonian Acad. Sci., (Estonia) (1979) pp. 32–36.], which used higher value of gas-phase velocity of 50 m/s.