Numerical Simulation for Drop Impact on Textured Surfaces

Abstract

Superhydrophobic surfaces with small-scale features have recently gained interest, because impacting droplets may bounce-off faster with respect to a flat superhydrophobic surface. For such surfaces the correct numerical prediction of the impact phenomena is very difficult. Our goal is the numerical study of drop impact on such surfaces using Free Surface 3D (FS3D), our in-house code for the simulation of incompressible multi-phase flows. Until recently, FS3D was not able to represent the interaction of a droplet with a complex textured solid surface. In this work, we show how we added this feature to the code by implementing the representation of embedded arbitrary-shaped boundaries using a Cartesian grid. Two approaches were developed; a preliminary simplified approach and an ultimate, more rigorous one. We discuss both implementations and we show a comparison of the two approaches for a test case. The results show that the predictions for impact dynamics of the two approaches slightly differ. Although, the simplified approach shows only small errors in mass conservation, it is fundamentally not conservative. With the introduction of a new approach we were able to improve the conservativeness of our simulations.