James B. Mehl
Dept. of Phys. and Astron., Univ. of Delaware, Newark, DE 19716-2570
NIST Gaithersburg, MD 20899
The acoustic fields and eigenfrequencies of double Helmholtz resonators
(Greenspan viscometers) have been investigated using a
boundary-integral-equation technique. The resonator geometry consists of a
circular duct connected at both ends to concentric cylindrical cavities.
Comparisons of the numerically determined fields with analytic expressions
based on a Green's function expansion establish the high accuracy of the
method. The acoustic flow near the duct-cavity orifices has the expected
singular behavior at the edge of the duct orifice. The associated duct-end
inertance corresponds to a length correction of approximately 0.82 times the
duct radii, slightly smaller than the classical formulas of Rayleigh and Ingard
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