Fully-Nonlinear Simulation of a Plunging Breaking Wave Impacting a Vertical Wall.

摘要

This thesis seeks to extend fully nonlinear potential flow theory to the problem of breaking wave impact upon a vertical wall. The validity of this theory as a basis for simulation of a deep-water plunging breaking wave was recently demonstrated by comparison of numerical results with experiments by Chan. The numerical approach used was a mixed Eulerian-Lagrangian method based upon application of Cauchy's integral theorem to the fluid domain. We apply this same approach to the wave impact problem. Chan's experimental results on the kinematics and dynamics of wave impact on a vertical wall provide a basis for comparison. First, the simulation of a plunging breaker in a long tank is repeated to examine the difficulties involved more closely and to investigate the influence of point regridding and smoothing routines upon the results. Next a shorter numerical tank is used with the same wavemaker input to force overturning to occur near the end of the tank. Difficulties with simulation are revealed which were not present with the longer tank, and techniques are developed to address them. A simulation is finally achieved in which the overturning wave reaches the end of the tank before re-entry into the free surface occurs. This allows imposition of an impact condition at the end of the tank. Techniques for simulating the impact process are then investigated. Preliminary results obtained for the impact simulations show qualitatively plausible flows in some cases, with formation of upward and downward moving jets along the wall after impact. (EDC)