Sound propagation in ducts with bulk reacting lining in the presence of laminar mean flow

In this Letter the problem of sound propagation in ducts lined with bulk reacting material in the presence of laminar mean flow is considered. The boundary conditions appropriate for the cases of circular and two-dimensional rectangular ducts with bulk reacting linings are formulated by making use of the analytical solutions of the sheared flow wave equations presented by the authors in their earlier work. These are then solved numerically. Results showing the effect of sheared mean flow on the attenuation of the lowest mode, and the comparison of locally reacting and bulk reacting linings are presented