A time-domain implementation of surface acoustic impedance condition with and without flow

Ozyoruk Y. , Long L.

JOURNAL OF COMPUTATIONAL ACOUSTICS, vol.5, no.3, pp.277-296, 1997 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 5 Issue: 3
  • Publication Date: 1997
  • Doi Number: 10.1142/s0218396x97000162
  • Page Numbers: pp.277-296


The impedance condition in computational aeroacoustic applications is required in order to model acoustically treated walls. The application of this condition in time-domain methods, however, is extremely difficult because of the convolutions involved. In this paper, a time-domain method is developed which overcomes the computational difficulties associated with these convolutions. This method builds on the z-transform from control and signal processing theory and the z-domain model of the impedance. The idea of using the z-domain operations originates from the computational electromagnetics community. When the impedance is expressed in the z-domain with a rational function, the inverse z-transform of the impedance condition results in only infinite impulse response type, digital, recursive filter operations. These operations, unlike convolutions, require only limited past-time knowledge of the acoustic pressures and velocities on the surface. Examples of one-and two-dimensional problems with and without how indicate that the method promises success in aeroacoustic applications.