Numerical investigation of head-on droplet collision with lattice Boltzmann method

In the present work, head-on droplet collision is numerically investigated with the lattice Boltzmann method (LBM). The simulation is based on the high density ratio LBM multiphase model for incompressible binary fluids proposed by Lee et al., and the model is implemented in the axisymmetric form. Compared with previous LBM-based numerical studies on droplet collision, density ratio is substantially increased. The investigation is conducted from aspects of effect of Weber number, effect of Ohnesorge number, effect of colliding velocity and unequal-size droplet collision. The evolution of total kinetic energy and cumulative dissipated energy are studied, and a very detailed picture of the collision process is presented and discussed with time-resolved evolution of the flow field, the kinetic energy distribution, and the viscous dissipation rate distribution, which provides a broader and more in-depth insight into the droplet dynamics and the energy transfer and dissipation process.