Development of the gas–liquid drag model for flows on sieve plates in distillation columns via direct numerical simulation

An accurate drag model of bubble swarms is essential for predicting gas–liquid flows on sieve plates in distillation columns. In this work, the drag force of bubbles is calculated by directly integrating the stress on bubble surface based on the volume of fluid method, thereby avoiding the force balance assumption in the traditional methods. Direct numerical simulations are systematically performed for gas–liquid flows on a sieve plate with a pore diameter of 6 mm at various inlet gas velocities. The correction factors for bubble swarm are formulated as a function of both the Reynolds number and gas holdup, thus distinguishing from the traditional models that consider only gas holdup. Then the drag model for bubble swarms is applied to the simulations of distillation columns using the two-fluid model for posterior analysis. The simulation results show a good agreement with experimental data particularly for gas holdup on the tray within the range of 0.1 to 0.4, with the average relative error of 8.75 % at different gas flow rates.