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The Very Near Field II An introduction to Very Near Field Holography
Technical Paper
2005-01-2446
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
In [1] is shown that very close (distance smaller than L/2Π) to a vibrating and flat structure with typical size L, the normal particle velocity and the (normal) structural velocity coincide. It is shown that with an acoustic particle velocity sensor the normal acoustic particle velocity close to the surface can be measured and that this velocity coincides with the surface velocity that is measured with a laser vibrometer or accelerometer.
In [1] it is also shown that in the very near field (contrary to the behavior in the near field) the particle velocity level doesn't depend upon frequency. Furthermore, in the very near field, there is a linear relationship between the particle velocity as measured and the structural velocity to be measured.
In this paper it is shown that the normal acoustic particle velocity appears to be a good representation of the structural velocity up to distances of L/2 (with L the size of the vibrating structure) and lateral movements of the structure are not measured by the lateral particle velocity. It is also shown that the lateral acoustic particle velocity is zero if the normal velocity is maximal.
A simple holography method is presented based on the very near field concept.
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Authors
Citation
de Bree, H., Svetovoy, V., and Visser, R., "The Very Near Field II An introduction to Very Near Field Holography," SAE Technical Paper 2005-01-2446, 2005, https://doi.org/10.4271/2005-01-2446.Also In
References
- de Bree H-E Svetovoy V.B. Raangs R. Visser, R. The very near field; theory, simulations and measurements of sound pressure and particle velocity in the very near field St. Petersburg 2004
- de Bree H.-E. et al. Elwensoek M. The Microflown: A novel device measuring acoustical flows Sensors and Actuators 552 557 1996
- Visser R. A boundary element approach to acoustic radiation and source identification University of Twente Enschede, The Netherlands 2004