Comparison of turbulent particle dispersion models in turbulent shear flows

Abstract

-This work compares the performance of two Lagrangian turbulent particle dispersion models: the standard model (e.g., that presented in Sommerfeld et al. (1993)), in which the fluctuating fluid velocity experienced by the particle is composed of two components, one correlated with the previous time step and a second one randomly sampled from a Wiener process, and the model proposed by Minier and Peirano (2001), which is based on the PDF approach and performs closure at the level of acceleration of the fluid experienced by the particle. Formulation of a Langevin equation model for the increments of fluid velocity seen by the particle allows capturing some underlying physics of particle dispersion in general turbulent flows while keeping the mathematical manipulation of the stochastic model simple, thereby avoiding some pitfalls and simplifying the derivation of macroscopic relations. The performance of both dispersion models is tested in the configurations of grid-generated turbulence (Wells and Stock (1983) experiments), simple shear flow (Hyland et al., 1999) and confined axisymmetric jet flow laden with solids (Hishida and Maeda (1987) experiments).

Study of four-way coupling on turbulent particle-laden jet flows

“…The normal stresses for the gas phase also show a reasonable agreement with the experiments. As an example, the normal stresses for both phases are plotted at the axial station x = 40 D (bottom left); it is necessary to point out that the underprediction of the particles u value is typical of the Lagrangian calculation of jet flows (Laín and Kohnen, 1999;Laín and Grillo, 2005) where the anisotropy of particle turbulence is much higher than that of the gas phase. The calculated particle radial stresses, however, agree much more better with the experimental data.…”

An Overview of the Lagrangian Dispersion Modeling of Heavy Particles in Homogeneous Isotropic Turbulence and Considerations on Related LES Simulations

“…Apart the choice of the constants A, B or C T , some other factors can influence the simulations and justify discrepancies, the number of computed trajectories, the choice of the random number generator or the time step ∆t. Lain and Grillo [134] simulated the Wells and Stock experiment [16] and a jet flow [135].…”

From dilute to dense gas-solid flows simulation: the CFB riser case study

“…The model utilized in the present thesis is based on a Langevin equation model, as taken from Sommerfeld et al (1993apud SOMMERFELD, 2001. Over the years, some constants suggested in the first works of Prof. Sommerfeld were changed, and the model presented herein follows more recent ones, such as Laín and Grillo (2007), Laín and Sommerfeld (2008) and all the ones following those. In this model, the gas fluctuation velocity at the m-th particle current position is correlated to the gas fluctuation velocity at the m-th particle previous position and to the gas turbulent quantities at the particle current position:…”