University of Cambridge > > Waves Group (DAMTP) > Non-Modal Scattering over a Hard-Soft Wall Transition within a Cylindrical Duct

Non-Modal Scattering over a Hard-Soft Wall Transition within a Cylindrical Duct

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If you have a question about this talk, please contact Shiza Naqvi.

When considering acoustics within a lined cylindrical duct, a parallel sheared flow may be considered. However, doing so introduces a critical layer singularity resulting in a pressure field that consists of the usual modal field and also a non-modal field. While early work suggested that while in many cases the non-modal contribution may be neglected within the far-field, more realistic flow profiles have revealed cases exist where the non-modal component is comparable or even dominant in the far-field. When considering the scattering problem caused by a change in the duct wall boundary condition, often used is a mode matching method, which naturally cannot account for the non-modal field. Instead, the Wiener-Hopf technique may be utilised to account for these contributions without resorting to just neglecting them. This allows us to their effects understood, and has the potential for future comparisons to be made. In this talk I will highlight the various effects that may impact the overall behavior of the system, setup and illustrate the solution to the resulting Wiener-Hopf problem, and finally give my predictions for the overall behavior of the outgoing scattered field including the non-modal effect. This may be completed for various incoming sound sources, including ones that are also non-modal.

This talk is part of the Waves Group (DAMTP) series.

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