Direct Numerical Simulation of the Motion of Particles Larger Than the Kolmogorov Scale in a Homogeneous Isotropic Turbulence

Predicting interactions between particles and a surrounding viscous fluid is the concern of many environmental and industrial applications. A Direct Numerical Simulation (DNS) of dilute isotropic turbulent particulate flow has been conducted in a periodic box, with 128³ grid points. The objective is to understand the modification of isotropic turbulence due to dispersed solid particles by analyzing the DNS results. Previous numerical simulations have been, for the most part, limited to the point-particle regime. On the opposite, in these simulations, the diameter of the particles is larger than the Kolmogorov length scale. In order to maintain a constant turbulent kinetic energy, a physical forcing scheme is implemented. Thereby, statistics on the characteristics of the particles are more reliable. Furthermore, interactions between particles are treated via a repulsing force, consequently, simulations are four-way coupling. Simulations are performed with a fictitious domain approach and with the penalty method. For solving the velocity-pressure coupling, an augmented Lagrangian optimization algorithm is used. Results present the influence of the particle phase on the turbulence spectrum. Moreover, the comparison with particle-free case is particularly interesting notably about the anisotropy of the flow caused by the presence of the particles.