Towards a model for splashing: An experimental program to analyze a splash in terms of its jets

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Many industrial and natural processes depend crucially on splashing, the collision of a liquid drop with a surface and its subsequent fragmentation into smaller droplets. Common yet important examples include inkjet printing, spray painting, spray cooling, precision soldering of microelectronics, pesticide spraying, fire suppression, airborne dispersal of seeds, bacteria, and viruses. Our ability to predict and control such phenomena is limited by an incomplete understanding of the fundamental process that governs these phenomena, the splash. The overarching goal of this proposal is a fundamental study of splashing using a newly-developed technique that makes it possible to measure the fluid dynamics of a splash with unprecedented spatial and temporal resolution. The project includes a significant educational component, including training of future scientist at the undergraduate and graduate level, outreach to unrepresented minorities in the K-12 community, and dissemination of science to the public through social media and collaborations with museums. The goal of this project is to develop a model of splashing by decomposing the splash in terms of jets. Jets are the high-speed sheets of liquid produced soon after drop impact. The objectives will be met by (1) measuring the jet's early time dynamics and stability, (2) determining the bifurcation points for qualitatively different dynamics, (3) measuring the most unstable wavelength and the resulting droplet distribution, (4) modeling the stability of jets and comparing with experiments, (5) studying jet production from an apparatus that removes the complications in splashing from drop impact. Experiments will record the evolution of the liquid-gas interface and the size distribution of droplets created during the splash using high speed X-ray and visible light imaging for a range of impact speeds with different liquid and gas combinations. These data will be supplemented with direct numerical simulations. This program is expected to (1) produce the highest resolution experimental characterization of splashing, (2) test the hypothesis that splashes can be analyzed in terms of jets, and (3) provide a fundamental basis for modelling more complicated process that involve changes of topology. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.