An Analytical Model for Boundary Layer Attenuation of Acoustic Modes in Rigid Circular Ducts With Uniform Flow

Abstract

An analytical model is derived for the attenuation of fundamental and higher-order (both axisymmetric and non-axisymmetric) acoustic modes caused by viscothermal losses in the acoustic boundary layer. Flow convection effects are included in the modeling by assuming a uniform mean axial velocity profile. The proposed model can be applied to calculate the damping of the acoustic waves propagating in wide circular flow ducts with rigid walls. A simple and effective way of including the mean flow convection in the modeling for the attenuation of the fundamental mode is also suggested.the