Drop Impact

When a liquid drop strikes a liquid surface it typically produces a splash, a sheet of liquid that rises rapidly and fragments into smaller droplets. Splashing is a common process in nature and industry, and it can be advantageous or disadvantageous depending on the circumstances. For example, splashing is detrimental in inkjet printing, pesticide spraying,
and lubrication whereas it is beneficial for dispersing biological agents, maximizing fuel combustion, and transferring gases across the air-sea interface. Given its importance across many physical and engineering applications, predicting splashing is a highly desirable and valuable capability.

Using experiments and simulations we have accomplished the following:

• We showed that the Rayleigh-Plateau instability accounts for droplet production in the simplest splashing morphology where there is a single jet.
• We pioneered the use of high speed X-ray imaging to observe the dynamics of splashes, and discovered features that were obscured when observed with visible light.
• We observed that there are multiple jets and that the multiplicity depends on configuration, namely the Weber and Reynolds numbers.
• We showed that the splash morphology is highly sensitive to the viscosity ratio of the gas and the liquid.

Publications

1. G. Agbaglah, M.-J. Thoraval, S. T. Thoroddsen, L. V. Zhang, K. Fezzaa, R. D. Deegan, "Drop impact into a deep pool: vortex shedding and jet formation", Journal of Fluid Mechanics, 764, R1 (2015)
2. G. Agbaglah, and R.D. Deegan, "Growth and instability of the liquid rim in the crown splash regime", Journal of Fluid Mechanics 752, 485 (2014)
3. L. V. Zhang, J. Toole, K. Fezzaa, R.D. Deegan, "Splashing from drop impact into a deep pool: multiplicity of jets and the failure of conventional scaling", Journal of Fluid Mechanics 703, 402 (2012)
4. L. V. Zhang, J. Toole, K. Fezzaa, R.D. Deegan, "Evolution of the ejecta sheet from the impact of a drop with a deep pool", Journal of Fluid Mechanics 690 , 5 (2012). See also Focus on Fluids article
5. L. V. Zhang, P. Brunet, J. Eggers, & R.D. Deegan, "Wavelength selection in the crown splash", Physics of Fluids 22, 122105 (2010)
6. R.D. Deegan, P. Brunet, & J. Eggers, "Complexities of splashing", Nonlinearity 21, C1–C11 (2008)