When does a drop stop bouncing on a cold surface?

Abstract

Drop bouncing is intriguing when interacting with solidification, and yet, such an interaction is less known. This paper delves into drop bouncing in practical three-dimensional printing conditions. A phase field model coupled with the enthalpy porosity model is employed to capture the evolving liquid–gas and liquid–solid interfaces. The model is discretized using a finite difference method on a half-staggered grid and is run in a parallel fashion. The parameters influencing drop bouncing are investigated. They include impact velocity, drop size, and surface wettability. Moreover, a theoretical model based on energy analysis is put forward to predict drop bouncing on cold surfaces. The major findings are as follows. For a fixed undercooling, increasing the impact velocity or reducing the contact angle will significantly reduce drop bouncing, while increasing the drop size does little to mitigate bouncing. The theoretical model suggests that for a fixed undercooling, bouncing is avoided if the maximum spread is larger than the critical value predicted by the theoretical model.