Optimization of a variable mouth acoustic horn

By using boundary shape optimization on the end part of a semi‐infinite waveguide for acoustic waves, we design transmission‐efficient interfacial devices without imposing an upper bound on the mouth diameter. The boundary element method solves the Helmholtz equation modeling the exterior wave propagation problem. A gradient‐based optimization algorithm solves the resulting least‐squares problem and the adjoint method provides the necessary gradients. The results demonstrate that there appears to be a natural limit on the optimal mouth diameter. Copyright © 2010 John Wiley & Sons, Ltd.