Internal generation of waves in 2D fully elliptic mild-slope equation FEM models

This paper looks at an alternative approach for the treatment of open boundaries in linear wave field simulations by means of fully elliptic mild-slope equation (MSE) finite elements models. In these kinds of models, the domain of investigation is traditionally contoured both by reflecting-absorbing boundaries, which simulate the coastline or the structures that emerge from the sea, and by an 'open' or 'artificial' boundary, which separates the sea region included in the domain from the semi-infinite region that extends outward to infinity. The approach presented here assumes the domain to be completely contoured by reflecting-absorbing boundaries. A total absorbing boundary is, in particular, assumed to separate the inner (finite) from the outer (semi-infinite) sea region. Sources of energy, which generate waves of specified height and period, are located within the domain along a line in the proximity of the inner-outer sea region boundary. Reflected and scattered waves can propagate over the generation line and are absorbed at the open boundary. Numerical tests have been carried out to simulate progressive and stationary waves in a channel and long waves around a fully reflecting circular island on a parabolic shoal, and to evaluate the amplification factors of a long and narrow bay. All these validation tests show a very good agreement with the available analytical solutions. A discussion is finally carried out on the advantages and disadvantages of the presented approach with respect to traditional ones. (C) 2003 Elsevier B.V. All rights reserved.