INTERNAL WAVE GENERATION IN AN IMPROVED 2-DIMENSIONAL BOUSSINESQ MODEL

A set of Boussinesq-type equations with improved linear frequency disp ersion in deeper water is solved numerically using a fourth order accu rate predictor-corrector method. The model can be used to simulate the evolution of relatively long, weakly nonlinear waves in water of cons tant or variable depth provided the bed slope is of the same order of magnitude as the frequency dispersion parameter. By performing a linea rized stability analysis, the phase and amplitude portraits of the num erical schemes are quantified, providing important information on prac tical grid resolutions in time and space. In contrast to previous mode ls of the same kind, the incident wave field is generated inside the f luid domain by considering the scattered wave field in one part of the fluid domain and the total wave field in the other. Consequently, wav es leaving the fluid domain are absorbed almost perfectly in the bound ary regions by employment of damping terms in the mass and momentum eq uations. Additionally, the form of the incident regular wave field is computed by a Fourier approximation method which satisfies the governi ng equations accurately in water of constant depth. Since the Fourier approximation method requires an Eulerian mean current below wave trou gh level or a net mass transport velocity to be specified, the method can be used to study the interaction of waves and currents in closed a s well as open basins. Several computational examples are given. These illustrate the potential of the wave generation method and the capabi lity of the developed model. (C) 1998 Elsevier Science Ltd. All rights reserved.