A new two-scale hydrodynamic model was proposed to describe large-scale motion and small-scale bubble wake turbulence. The large-scale shear induced turbulence was resolved by classical k-ε turbulence model

while the small-scale bubble wake turbulence was quantitively described by wake temperature transport equation. A wake pressure gradient source term was added to the motion equation to reflect the mutual influence between small scale turbulence and large scale fluid motion and to explain the mechanism of holdup non-uniform distribution in the bubble column. The model classified the energy dissipation into three kinds of mechanism: large-scale shear induced turbulence dissipation

small-scale wake turbulence dissipation

energy dissipation due to interaction between bubble wake and solid wall. The model well resolved the issue about energy balance. Simulation results agreed well with experiment data