The Eulerian-Lagrangian simulation of bubbly flow has the advantage of tracking the motion of bubbles in continuous fluid

and hence the position and velocity of each bubble could be accurately acquired. Previous simulation usually used the hard-sphere model for bubble-bubble interactions

assuming that bubbles are rigid spheres and the collisions between bubbles are instantaneous. The bubble contact time during collision processes is not directly taken into account in the collision model. However

the contact time is physically a prerequisite for bubbles to coalesce

and should be long enough for liquid film drainage. In thiswork we applied the spring-dashpot model to model the bubble collisions and the bubble contact time

and then integrated the spring-dashpot model with the film drainage model for coalescence and a bubble breakage model. The bubble contact time is therefore accurately recorded during the collisions. We investigated the performance of the spring-dashpot model and the effect of the normal stiffness coefficient on bubble coalescence in the simulation. The results indicate that the spring-dashpot model together with the bubble coalescence and breakage model could reasonably reproduce the two-phase flow field

bubble coalescence and bubble size distribution. The influence of normal stiffness coefficient on simulation is also discussed.