Initial values for the integration scheme to compute the eigenvalues for propagation in ducts
Abstract
It has been found that in the integration method for calculating the eigenvalues for propagation in twodimensional ducts with flow care must be taken not to exclude roots which in the hardwall case are at infinity. When the real part of the wall admittance is positive starting values for the integration procedure to obtain these extra eigenvalues can be obtained by a limiting case analysis. When the imaginary part of the admittance is negative it appears that all the roots can be accounted for by the usual hardwall initial values κ_{n}b = nπ.
 Publication:

Journal of Sound Vibration
 Pub Date:
 January 1977
 DOI:
 10.1016/0022460X(77)905594
 Bibcode:
 1977JSV....50..159E
 Keywords:

 Acoustic Ducts;
 Acoustic Propagation;
 Ducted Flow;
 Eigenvalues;
 Two Dimensional Flow;
 Acoustic Impedance;
 Acoustic Measurement;
 Boundary Value Problems;
 Mach Number;
 Numerical Integration;
 Propagation Modes;
 Acoustics