The Scattering of Sound by a Region of Fluid in Solid Body Rotation at Low Mach Number.
Abstract
This example, which is one of the simplest to exhibit vortex refraction of sound, is solved using an approximation which is uniformly valid at all frequencies and small Mach numbers. The region of solid body rotation is bounded by a vortex sheet which implies that the results obtained have little physical relevance. However this flow field gives acoustic equations which are comparatively easy to solve and thus an ideal test case for the various approximate techniques used to investigate the effect of more realistic vortices on sound. The present Report gives an assessment of a method which sets out to express the acoustic pressure as an asymptotic power series in the Mach number. It is found that this approach produces an error which increases progressively as the frequency increases at a fixed Mach number. At higher frequencies it appears that the ray theory approximation is likely to be more accurate and it is hoped to publish an assessment of the utility of this method later. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1978
- Accession Number
- ADA070293
Entities
People
- Kevin Taylor
Organizations
- Royal Aircraft Establishment