PR-DNS verification of the stability condition in the EMMS model

Abstract

The energy-minimization multi-scale (EMMS) model has succeeded in describing the mesoscale structures in gas–solid fluidization by introducing a stability condition to complete the model, viz., the mass specific energy consumption for suspending and transporting the solids, Nst tends to be a minimum. However, direct verification of this condition is very limited so far. This work, therefore, monitors the evolution of Nst in particle-resolved direct numerical simulation (PR-DNS) of a small-scale fluidized bed. Compared with the earlier simulation study on this issue based on pseudo-particle modeling (PPM), this work is more comprehensive thanks to the higher computational efficiency of PR-DNS. As a result, the previously neglected acceleration effect is now included in the force balance and the fluidization system is simulated under different initial distributions. The simulation and analysis demonstrate that, the stability condition is satisfied in all the cases, which further verifies the EMMS model. With PR-DNS as a powerful tool, deeper understanding of the EMMS model and gas–solid fluidization can be achieved in the future.