In this paper, the pseudo-potential based lattice Boltzmann model of Li and Luo [1] is implemented to study the effect of the kinematic viscosity ratio of gas to liquid and the density ratio of liquid to gas on a droplet impact onto a thin liquid film. The model has certain capabilities which make it applicable to cases with large density ratios, low viscosities, and tunable values of surface tension independent of the density ratio. The coexistence values (densities) from the numerical model are compared to those of the analytical solution of the Maxwell construction. For further validation of the model, the simulation results for pressure difference at the interface are compared to those of the theoretical solution based on the Laplace law. Simulation results of the droplet impact onto a thin liquid film show that at high density ratios such as 1000 selected in this paper, when the kinematic viscosity ratio of the gas to liquid is high (above 150), no secondary droplets are generated. As the gas viscosity is decreased, however, the splashing leads to liquid breakup and separation of the secondary droplets. It was also found that the density ratio has a significant effect on the impact phenomenon. For a case with a low density ratio of 10, the liquid rise from the surface cannot move freely in radial and vertical directions leading to the formation of an inward liquid turn on top of the raised liquid sheet.

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