An Extended Transfer Matrix Approach to Model the Effect of Boundary Layers on Acoustic Linings
(English)Manuscript (preprint) (Other academic)
Sound absorbing materials exposed to grazing flow experience a change in the surface properties due to the boundary layer developed above the surface. The effect of this boundary layer is significant even for fairly low Mach numbers, and several attempts to find analytical models to describe this effect have previously been made. This paper proposes a numerical discretization method, based on the classic transfer matrix approach to model the boundary layer effect. The method includes the time averaged flow velocity gradients of the boundary layer, which is shown to be essential in order to obtain convergence to the correct solution. The method is found to predict the effect of the boundary layer on the surface properties correctly compared to previous numerical solutions. The proposed method is simple to implement, and benets from a fast convergence relative to other numerical methods.
grazing flow, surface impedance, sound absorption
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:kth:diva-128560OAI: oai:DiVA.org:kth-128560DiVA: diva2:648095