CFD-DPTM-VOF numerical simulation of particle motion and entrainment under the action of single and double bubbles

In this paper, the three-phase flow, particle motion and entrainment process under the action of single and double bubbles were simulated through the use of computational fluid dynamics-deterministic particle track model-volume of fluid (CFD-DPTM-VOF). First, the physical model was established and the gas-liquid was regarded as a continuous phase. The gas-liquid flow was modeled as turbulent, described by the RNG k-ε model. The volume of fluid (VOF) was used for establishing the gas-liquid interface. Particles were regarded as a discrete phase. DPTM were used for tracking particle motion. Second, the simulation results were compared with the experimental results based on the analysis of grid independence. The simulation results were in good agreement with the experimental results. Third, the influence of bubble motion on particle distribution and entrainment was revealed through simulation and analysis. The entrainment law of 10, 50, 100, and 500 μm particles were described qualitatively and quantitatively. Numerical results showed that the vortex region formed by the rising bubbles had a notable entrainment effect on the 10, 50, and 100 μm particles, which caused the bottom of the bubbles to form upward velocity. The 10 μm particles were mostly suspended in the liquid pool, while the 500 μm particles were mostly unaffected by bubble entrainment and mainly concentrated at the bottom of the liquid pool. In addition, the height of entrainment and number of entrainment particles decreased as particle size increased under the action of single and double bubbles. Our findings indicate that, compared with single bubble, double bubbles have two entrainment processes, and particles can be carried to a higher height with an increased number of entrained particles at the same time. The work lays a foundation for further explorations on the gas-liquid-solid flows and possible industry applications.