Effects of Wave Breaking Action on Flows in Tidal-flats
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In this paper, we construct a mathematical model for flows above and under the tidal-flat. First we construct a mathematical model for flows above and under the tidal-flat. Then we unify the flow equations defined in different regions into single equation by means of fictitious domain method via singular perturbation. Thanks to the unified equation, numerical simulation becomes much simpler. We obtain several observations from our numerical simulations of wave breaking action on the tidal-flats by use of some extracting techniques. First technique is a time-averaging technique, in which we compute a time-averaged flow field and draw time-averaged streamlines. Time averaged streamlines show how the seawater circulates in the tidal-flat. This phenomenon affects to distribution of silts (small sand particles) in sand, which is important for bacteria to live. Our observation is in good agreement with an experimental observation. Second technique is a streak lines technique, by which we trace the loci of fluid particles. We can see a radial direction flow starting from a source point, which is located in a little bit lower than maximum run-up point. This observation is also in good agreement with the experimental results.
KeywordsFree Surface Tidal Flat Wave Breaking Sand Beach Virtual Particle
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