Time-dependent force in high-speed liquid droplet impacting on a wet wall

Abstract

Recent research (Fujisawa, 2022a) has shown that the time-dependent force exerted on a droplet during high-speed [O (100 m/s)] impact on a planar rigid wall is quite different from that of low-speed [O (1 m/s)] impact case owing to the compressibility of the droplet. Here, we consider a more general case of a high-speed liquid droplet impacting a wall where a liquid film is present on the wall surface. Three-component Euler simulations were performed to determine the characteristics of the time-dependent force exerted on the droplet during high-speed liquid droplet impact on a planar rigid wet wall. Several initial liquid film thicknesses were considered. The strength of the force exerted on the droplet decreases in magnitude as the liquid film thickness increases, whereas the total force increases with increasing liquid film thickness owing to the presence of a water hammer shock that is reflected inside the liquid film.