Alternative wetting boundary condition for binary fluids based on phase-field lattice Boltzmann method

Based on the phase-field theory, a new wetting boundary condition (WBC) scheme is proposed to describe the fluid-solid interaction of binary fluids. Different from the common linear, cubic and sine form of surface energy wetting conditions, we adopt a mixed cubic and sine form of free energy in the present scheme. Two conditions are given to ensure that the spurious film at the solid surface disappears and the reasonable boundary condition is obtained. Combined with the wetting scheme and lattice Boltzmann (LB) method based on phase-field theory, numerical simulation of droplet spreading on a cylindrical surface is carried out to verify the performance of the present WBC. It is found that the present wetting scheme can offer considerable accuracy for predicting a static contact angle, which means that it can be used to study the wetting boundary problems of binary fluids.