Related Experiment Video
Updated: Aug 19, 2026

Investigating the Three-dimensional Flow Separation Induced by a Model Vocal Fold Polyp
Published on: February 3, 2014
Quasisteady aero-acoustic response of orifices
P Durrieu1, G Hofmans, G Ajello
1Laboratoire d'Acoustique Université du Maine, URA CNRS 1101, Le Mans, France.
Abstract:
The low frequency response of orifices (slit, circular diaphragm, and perforated plate) in the presence of mean flow is well predicted by a quasisteady theory. A refinement is brought to the theory by considering a Mach number dependent vena contracta coefficient. The measurements of the vena contracta coefficient of a slit agree well with the simple analytical expression existing in the case of the Borda tube orifice. The measured scattering matrix coefficients do not depend strongly on the geometry of the element. If the frequency is increased the moduli remain relatively unaffected while the arguments exhibit a complex behavior which depends on the geometry. From these considerations an anechoic termination efficient at high mass flow is designed.
Related Concept Videos
Sound Waves: Interference
Sound Waves: Resonance
Deriving the Speed of Sound in a Liquid
The speed of sound in fluids can be derived by considering a mechanical wave propagating...
Anatomy of the Ear
Physical Assessment of the Respiratory Tract IV: Auscultation
Breath Sounds
Breath sounds are categorized into vesicular, bronchovesicular, and bronchial.
Respiratory System Abnormal Finding II: Palpation and Auscultation
Palpation Findings
During a respiratory assessment, palpation can reveal several vital abnormalities:

