Muffler analysis using the direct mixed-body boundary element method and an efficient four-pole approach

Muffler analysis is a good example of using the boundary element method in industrial applications. Typical mufflers or silencers used in industry usually contain complex internal components such as extended inlet/outlet tubes, thin baffles with eccentric holes, internal connecting tubes, perforated tubes, flow plugs, and sound absorbing materials. In this paper, the direct mixed-body boundary element method for muffler analysis is briefly reviewed. The transmission loss is evaluated by an improved four-pole method that does not require solving the boundary element matrix twice. Numerical predictions are compared to experimental measurements, including test cases with a mean flow in the perforated tube.