Archives of Acoustics, 34, 4, pp. 625-639, 2009

Acoustic Streaming Caused by Some Types of Aperiodic Sound. Buildup of Acoustic Streaming

Anna PERELOMOVA
Gdańsk University of Technology, Faculty of Applied Physics and Mathematics

Paweł WOJDA
Gdańsk University of Technology, Faculty of Applied Physics and Mathematics

The analysis of streaming caused by aperiodic sound of
different types (switched on at transducer sound or sound determined by initial
conditions) is undertaken. The analysis bases on analytical governing equation
for streaming Eulerian velocity, which is a result of decomposition of the
hydrodynamic equations into acoustic and non-acoustic parts. Its driving force
(of acoustic nature) represents a sum of two terms; one is the classic one,
which, being averaged over the sound period, coincides with the well-known
expression. The second one depends on the periodicity of the sound; at the axis
of beam propagation it becomes exactly zero after averaging for the strictly
periodic sound but differs from zero for other acoustic waves. Both terms are
nonlinear and proportional to the standard attenuation due to shear, bulk
viscosities and thermal conductivity. Numerical analysis reveals a qualitative
agreement with experimental data. Some theoretical conclusions concerning
features of streaming caused by sound determined by initial conditions, are
made.
Keywords: instantaneous acoustic streaming; radiation force; non-linear sound propagation
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