Numerical Simulation of Sessile Droplet Spreading and Penetration on Porous Substrates

Numerical simulation is performed for sessile droplet spreading and penetration on porous surfaces in this study. The volume of the fluid model is used to accurately track the droplet deformation, and the pressure implicit split operator algorithm is presented to calculate the coupling of the droplet pressure and velocity. The effects of droplet characteristics, porous media characteristics, and the wettability of liquid/porous media on sessile droplet spreading and permeation are investigated in detail. The studied problem can be characterized by four control parameters: the Bond number, Darcy number, static equilibrium contact angle, and ratio between the initial diameter of the droplet and the particle diameter in the porous substrate. The numerical simulations show that droplet spreading and penetration are competitive with each other and dependent on the above four dimensionless parameters. The results obtained in this work are of benefit to provide deep insights into the dynamic behavior of sessile droplet on porous substrates.