HYDROACOUSTICS
ANNUAL JOURNAL
START NEW VOL 20 SEARCH STATISTICS PAS - GDANSK DIVISION

Single burst acoustic streaming

pp. 197-200, vol. 4, 2001

G. Pedersen
Department of Physics, University of Bergen, Bergen, Norway

H. Hobćk
Department of Physics, University of Bergen, Bergen, Norway

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Abstract: On a previous occasion we reported observations of a new type of acoustic streaming which only occurred around a needle hydrophone positioned near the focus of a focusing ultrasound transducer. The streaming was observed even at burst repetition frequencies as low as l Hz. In an attempt to find the origin of this streaming attention was focused on possible excitation of evanescent waves on the probe surface. Presently we report results front a new experiment on this subject. Streaming was observed and measured using tiny tracer particles of polyamid which were recorded with a CCD-video camera and a frame grabber in a PC. The frames were analysed with a Matlab-program for obtaining stream lines and velocity measurements in a vertical plane through the sound axis. The results show that we also observe streaming in free field when using burst repetition frequencies lower than l Hz, and even when using single bursts.

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© Polish Acoustical Society - Gdansk Department, Polish Academy of Sciences. This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported. (CC BY-NC-SA 3.0)