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On vortex sound at low Mach number

Published online by Cambridge University Press:  12 April 2006

W. Möhring
W. Möhring
Affiliation:
Max-Planck-Institut für Strömungsforschung, Göttingen, West Germany
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Abstract

A transformation is described which relates the sound generated by low Mach number flow to the flow vorticity. For compact flow fields the apparent sound source is of quadrupole type and linear in the vorticity and therefore also linear in the flow velocity. This scheme is applied to the sound generated by the interaction of two identical thin vortex rings. Then a flow field with a number of compact vortices is discussed. It is found that each vortex can be replaced acoustically by a dipole related to the impulse of the vortex, plus the quadrupole just mentioned plus a spherically symmetric sound source related to the energy of the vortex. An application to low Mach number free-space turbulence shows that the generated sound is related to the vorticity correlation tensor.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 85 , Issue 4 , 27 April 1978 , pp. 685 - 691
Copyright
© 1978 Cambridge University Press

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