Improved contact angle measurement in multiphase lattice Boltzmann

Contact angle is an essential parameter to characterize substrate wettability. The measurement of contact angle in experiment and simulation is a complex and time-consuming task. In this paper, an improved method of measuring contact angle in multiphase lattice Boltzmann simulations is proposed, which can accurately obtain the real-time contact angle at a low temperature and larger density ratio. The three-phase contact point is determined by an extrapolation, and its position is not affected by the local deformation of flow field in the three-phase contact region. A series of simulations confirms that the present method has high accuracy and gird-independence. The contact angle keeps an excellent linear relationship with the chemical potential of the surface, so that it is very convenient to specify the wettability of a surface. The real-time contact angle measurement enables us to obtain the dynamic contact angle hysteresis on chemically heterogeneous surface, while the mechanical analyses can be effectively implemented at the moving contact line.