We explore the effects of fluid films of variable depths on droplets impacting into them. Corresponding to a range of fluid "film" depths, a non-dimensional parameter-H*, defined as the ratio of the film thickness to the droplet diameter-is varied in the range 0.1 ≤ H* ≤ 10. In general, the effect of the fluid film imposes a dramatic difference on the dynamics of the droplet-surface interaction when compared to a similar impact on a dry surface. This is illustrated by the size distribution and number of the splash products. While thin fluid films (H*≈0.1) promote splashing, thicker films (1 ≤ H* ≤ 10) act to inhibit it. The relative roles of surface tension and viscosity are investigated by comparison of a matrix of fluids with low and high values of these properties. Impingement conditions, as characterized by Reynolds and Weber numbers, are varied by velocity over a range from 1.34 to 4.22 m/s, maintaining a constant droplet diameter of 2.0 mm. The dependence of splashing dynamics, characterized by splash product size and number, on the fluid surface tension and viscosity and film thickness are discussed.
All Science Journal Classification (ASJC) codes
- Computational Mechanics
- Mechanics of Materials
- Physics and Astronomy(all)
- Fluid Flow and Transfer Processes