Statistics in particle-laden plane strain turbulence by direct numerical simulation

Direct numerical simulation is utilized to generate statistics in particle- laden homogeneous plane strain turbulent flows. Assuming that the two-phase flow is dilute (one-way coupling), a variety of cases are considered to in vestigate the effects of the particle time constant. The carrier phase is i ncompressible and is treated in the Eulerian frame whereas the particles ar e tracked individually in a Lagrangian frame. For small particle Reynolds n umbers, an analytical expression for the particle mean velocity is found, w hich is different from the fluid one, and the dispersed phase is shown to b e homogeneous. This is not the case for particles with large Reynolds numbe rs and no statistics involving particle fluctuating velocity is presented f or large particles. The results show that the root mean square (r.m.s.) of the particle velocity in the squeezed direction exceeds that of the fluid i n the same direction and increases with the particle time constant. The mea n velocity gradient component in the elongated direction has the opposite e ffect, that is the r.m.s. of the particle velocity is decreased below that of the fluid in this direction. Further, the dispersed phase exhibits a lar ger anisotropy than the fluid phase, and its anisotropy increases with the particle inertia. Dispersion is shown to depend strongly on the injection l ocation and quantified dispersion results show that increasing the injectio n location coordinates in the strained directions increases the dispersion. (C) 2001 Elsevier Science Ltd. All rights reserved.