Guided wave propagation and scattering in pipe-works comprising elbows

Guided waves (GW) are used to inspect pipe-works in various industries. Specific features of pipe-works lead to complex scattering phenomena. Simulations tools able to handle such a complexity must be developed to help interpretation and to optimize testing configurations. They must handle both long range propagation and local scattering phenomena. Here, a modal formulation is derived to deal with pipe-works comprising arbitrarily curved elbows linking otherwise straight pipes. First, the semi-analytic finite element method is extended in curvilinear coordinates to predict guided modes in elbows. Then, GW scattering at the junction of a straight pipe with an elbow is investigated. Modal solutions in both parts being known, the mode matching method is derived to compute modal reflection and transmission coefficients given as elements of a scattering matrix. Further, the global scattering matrix of a pipework comprising an arbitrary number of elbows linking straight pipes is considered. A general formulation presented in this conference series is used which handles multiple scattering phenomena that possibly arise. Interestingly, the computation of both modal solution and the scattering matrix with mode-matching method only requires meshing the pipe section. Examples illustrate the various steps. (authors)