Simulation of impingement and spreading of micro-droplet on non-homogeneous solid surface

This paper presents a numerical study on the impingement and spreading of a micro-sized droplet on a nonhomogenous solid surface. Based on the phase field method, the numerical model was implemented with finite element method (FEM). Dynamic contact angle, which is dependent on the droplet contact line velocity, was applied at the contact surface based on Blake's model and hydrodynamic model. A novel scheme to specify the contact line velocity based on the phasefield function gradient at the interfacial region has been implemented. Numerical results show that a high wettability difference between two surfaces confines the spreading of an impinging micro-sized droplet. Surface wettability patterning can be applied to control the deposition and spreading of a jetted droplet to produce accurate micro-sized features in electronic circuits.