Regensburg 2010 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 32: Fluid Dynamics
DY 32.1: Talk
Friday, March 26, 2010, 10:15–10:30, H47
Supersonic Air Flow due to Solid Object Impact — •Stephan Gekle1, Ivo Peters1, Jose Manuel Gordillo2, Devaraj van der Meer1, and Detlef Lohse1 — 1Physics of Fluids, University of Twente, The Netherlands — 2Mecanica de Fluidos, Universidad de Sevilla, Spain
A solid object impacting on liquid creates a liquid jet due to the collapse of the impact cavity. Using visualization experiments with smoke particles and multiscale simulations we show that in addition a high-speed air-jet is pushed out of the cavity. Despite an impact velocity of only 1 m/s, this air-jet attains supersonic speeds already when the cavity is slightly larger than 1 mm in diameter. The structure of the air flow resembles closely that of compressible flow through a nozzle – with the key difference that here the “nozzle” is a liquid cavity shrinking rapidly in time.