Numerical simulation of multi-scale three-phase flows in a Sequencing Batch Reactor
序批式反应器内多尺度三相流动的数值模拟

A hybrid model is presented for three-dimensional simulation of multi-scale gas-liquid-solid flows in a sequencing batch reactor (SBR).This model describes the motion of the aeration bubble,continuous liquid phase and activated sludge solid phase,based on the level-set method,the volume-averaged Navier-Stokes equations,and the discrete particle approach.Various interactions of particle-bubble,gas-liquid,and particle-liquid are taken into account in the model.The validity of the simulation based on this model is examined through several typical dynamic processes including aeration bubble formation and rising,and sludge sedimentation in the SBR.The simulation results of flow structure reveal the internal circulation of the sewage and sludge with upward flow in the center region and downward flow near the wall in the SBR.Bubble breakage due to bubble-particle interaction results in the appearance of a number of small size bubbles and good dispersion of particles.These hydrodynamic characteristics make the sewage and activated sludge mix fully,which is favorable to the biodegradation process.