8.1 Regular Perturbations 8.1. 1 Webster's horn equation 8.2 Multiple scales......... 8.3
Helmholtz resonator with non-linear dissipation 8.4 Slowly varying ducts......... 8.5 Reflection …

An explicit solution is given of a pulse reflecting in time domain at a Helmholtz resonator
impedance wall that provides some insight into the reflection problem in time domain and at …

The Ingard–Myers condition, modelling the effect of an impedance wall under a mean flow
by assuming a vanishingly thin boundary layer, is known to lead to an ill-posed problem in …

The walls of ducts containing flow are often acoustically lined in order to reduce sound.
Many simple models of acoustic linings assume the lining to be linear and locally reacting; …

Time-domain impedance boundary conditions are reviewed and similarities between the
models are shown. The extended Helmholtz resonator model is used with a time-domain …

A methodology to design broadband time-domain impedance boundary conditions (TDIBCs)
from the analysis of acoustical models is presented. The derived TDIBCs are recast …

An analytic Green's function is derived for a lined circular duct, both hollow and annular,
containing uniform mean flow, from first principles by Fourier transformation. The derived …

Abstract An explicit Wiener–Hopf solution is derived to describe the scattering of sound at a
hard–soft wall impedance transition at x= 0, say, in a circular duct with uniform mean flow of …

AEROENGINE noise reduction is, in today's turbine design, achieved principally by using
passive-acoustic treatments. Reductions of noise in the forward arc of aeroengines are …

A new and efficient time-domain implementation is proposed for the impedance model
originally introduced by Tam and Auriault (Tam, CKW, and Auriault, L.,“Time-Domain …