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| In gas-liquid bubbly flow, due to marked density difference between gas and liquid phases, some no-drag forces, such as virtual mass force, pressure gradient force, etc., may become important. In this case, the effect of these no-drag forces on the turbulent dispersion of gas bubble should be considered. Buwa et al.[1] have used an eddy lifetime (EL) model to simulate the turbulent dispersion in bubble column and neglected the effect of these forces on the renew time scale of turbulent fluctuations, but our simulations showed the EL model wasn’t fully applicable to stirred tank because of high non-homogeneous turbulence. In this work, based on the analysis of forces exerted on gas bubble, we obtained an eddy-bubble interaction (EBI) model, which coupled the neglected the effect of these forces on the renew time scale of turbulent fluctuations, but our simulations showed the EL model wasn’t fully applicable to stirred tank because of high non-homogeneous turbulence. In this work, based on the analysis of forces exerted on gas bubble, we obtained an eddy-bubble interaction (EBI) model, which coupled the effect of no-drag forces and used the eddy-bubble interaction time as the renew time scale. The relationship of crossing time and eddy lifetime was discussed, and the radial, axial velocities and gas holdup distribution predicted by the EBI and EL models were also compared with the experimental data, we found that the crossing time showed obviously different from the eddy lifetime, the crossing time may be much smaller than the eddy lifetime in some positions and the EBI model predicted much bigger slip velocity in the discharge flow region and lower circulation region near the tank wall, and somewhat smaller axial velocity in the upper circulation part, the predicted gas holdup distribution showed a better agreement with the experiment data than that predicted by the EL model. |
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| Keywords:eddy-bubble interaction;turbulent dispersion;gas-liquid;stirred tank;Eulerian-Lagrangian |
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