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DY: Fachverband Dynamik und Statistische Physik

DY 32: Fluid Dynamics

DY 32.1: Vortrag

Freitag, 26. März 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.