Diffraction loads on multiple vertical circular cylinders by least-squares Trefftz-type finite elements

The paper deals with the application of the so-called "frameless" Trefftz-type finite elements to the calculation of wave induced loads on the offshore, seabed, cylindrical structures. The method is based on the use of a suitably truncated $ T$-complete set of Trefftz functions over individual subdomains linked by means of a least square procedure. The Neumann homogeneous boundary conditions and the Sommerfeld radiation condition are readily incorporated in the trial functions of special purpose finite elements.