Modeling of Fluid Turbulence Modulation and Pseudo-Turbulence Production By Particles in Liquid-Solid Fluidized Bed

Numerical modeling of fluidized bed processes from lab scale to industrial scale by N-Euler CFD modeling approaches is becoming an essential tool to support the optimization or scaling-up of existing processes and the development of new processes based on innovative concepts. The liquid-solid fluidized beds are used in numerous processes, including chemical, biochemical and catalytic reactions. To gain an understanding on this complex industrial process requires a greater knowledge of the multi-scale hydrodynamic interactions that exist between the particle and the fluid phases.

A new two-way coupling model is proposed to account for both the effect of particles on the large scales of the fluid turbulent motion and production of velocity fluctuations in the wakes of the particles. This approach is based on separate equations and particle modulation terms for large-scale turbulence Reynolds stresses and for pseudo-turbulence kinetic energy. This modelling approach will be implemented in neptune_cfd code and apply to simulate a 3D liquid-solid fluidized bed. The simulation results are going to be compared with experimental results from Almeras et al. (2021). This new mathematical modeling will increase the fluid velocity fluctuation prediction due to the contribution of the pseudo-turbulence without relevant impact of prediction on particle velocity fluctuation.

In addition, a study will also be presented on the effects of different types of rheological models of the liquid phase: either homogeneous as a function of the solid volume fraction or as a function of the local pseudo-turbulence. The impact of these models on the spatial and time velocity variances of the fluid will be investigated.