The Effect Of The Instability Of Alongshore Current On Substance Transport

With the rapid development of the economy at the coastal areas , the oceanic exploitation and transportation become gradually active .The total amount of pollutant flown into the sea maintains high, the polluted area expands, and environmental quality of the ocean falls down obviously. The rules of the pollutants transport due to the coastal hydrodynamics should be studied to protect and improve the ocean environment. The longshore current has important influences on the transport and diffusion of pollutants besides on the sediment transport in the near-shore region. In the paper, numerical simulation is used to compute the pollutant transport rule induced by the instability of the longshore current. The main content includes these parts as follows:(1)The longshore current model and the pollutant transport model are introduced, the discrete method and correlation coefficient are analyzed in detail, and the numerical results of the convective-diffusion model have been validated by the example of the point source.(2)Based on the analysis of the pollutant transport acted by the stable longshore current ,the wave height, the wave set-up and set-down ,and the longshore current velocity under eight work condition during the experiment are calculated and the compatibility of the numerical simulation results and the experiment results is validated by comparing with the experimental observed value.(3) This paper emphasises on the analysis of the pollutant movement induced by the instability of the longshore current. The instable movement of the longshore current is simulated by adding periodic destabilization on the upper border of the longshore current to generate the swing phenomenon .The pollutant diffusion in the action of continuous sources caused by the instable longshore current is calculated. The primary goal of this research is to discuss the swing phenomenon of the ink in the process of transport along the coast observed in the experiment. The inference that the swing phenomenon in the process of pollutant transport observed in the experiment is induced by the instability of the longshore current is validated.