Lattice Boltzmann simulations for self-propelled jumping of droplets after coalescence on a superhydrophobic surface

The phenomenon of coalescence induced droplets self-propelled jumping on superhydrophobic surfaces (SHS) is numerically simulated in this paper using 2D lattice Boltzmann method (LBM). To overcome numerical instability problems of a two-phase flows with a high liquid/vapor density ratio and a high liquid/vapor viscosity ratio, the equation of state is modified according to an existing method and the multiphase relaxation time (MRT) method is adopted. The simulated jumping velocity and jumping height of droplets with different radii are found in good agreement with experimental observations. In addition, the reason why coalescence droplets will jump on superhydrophobic surface with a sufficiently high contact angle is explained based on a qualitative analysis.