Stochastic modeling of subgrid-scale effects on particle motion in forced isotropic turbulence

Publication date: Available online 29 May 2019Source: Chinese Journal of Chemical EngineeringAuthor(s): Haoshu Shen, Yuxin Wu, Minmin Zhou, Hai Zhang, Guangxi YueAbstractThe subgrid-scale effects on particle motion were investigated in forced isotropic turbulence by DNS and prior-LES methods. In the DNS field, the importance of Kolmogorov scaling to preferential accumulation was validated by comparing the radial distribution functions under various particle Stokes numbers. The prior-LES fields were generated by filtering the DNS data. The subgrid-scale Stokes number (StSGS) is a useful tool for determining the effects of subgrid-scale eddies on particle motion. The subgrid-scale eddies tend to accumulate particles with StSGS < 1 and disperse particles with 1 < StSGS < 10. For particles with StSGS ≫ 1, the effects of subgrid-scale eddies on particle motion can be neglected. In order to restore the subgrid-scale effects, the Langevin-type stochastic model with optimized parameters was adopted in this study. This model is effective for the particles with StSGS > 1 while has an adverse impact on the particles with StSGS < 1. The results show that the Langevin-type stochastic model tends to smooth the particle distribution in the isotropic turbulence.
Source: Chinese Journal of Chemical Engineering - Category: Chemistry Source Type: research