  A rigorous free energy model for ternary fluid flows with density ratio up to
of order $O(10^3)$ is presented and implemented using the entropic lattice
Boltzmann scheme. The model is thermodynamically consistent and allows a broad
range of surface tension ratios, covering both partial wetting states where
Neumann triangles are formed, and full wetting states where complete
encapsulation of one of fluid components is observed. We further demonstrate
that we can capture the bouncing, adhesive and insertive regimes for the binary
collisions between immiscible droplets suspended in air. Our approach opens up
a vast range of multiphase flow applications involving one gas and several
liquid components.
