Lattice Boltzmann simulations of micron-scale drop impact on dry surfaces

A lattice Boltzmann equation (LBE) method for incompressible binary fluids is proposed to model the contact line dynamics on partially wetting surfaces. Intermolecular interactions between a wall and fluids are represented by the inclusion of the cubic wall energy in the expression of the total free energy. The proposed boundary conditions eliminate the parasitic currents in the vicinity of the contact line. The LBE method is applied to micron-scale drop impact on dry surfaces, which is commonly encountered in drop-on-demand inkjet applications. For comparison with the existing experimental results [H. Dong, W.W. Carr, D.G. Bucknall, J.F. Morris, Temporally-resolved inkjet drop impaction on surfaces, AIChE J. 53 (2007) 2606–2617], computations are performed in the range of equilibrium contact angles from 31° to 107° for a fixed density ratio of 842, viscosity ratio of 51, Ohnesorge number (Oh) of 0.015, and two Weber numbers (We) of 13 and 103.