The Numerical Method Study Of Water Exchange For Sea Bay

21th century is the "Ocean Century". The ocean has rich resources and is asupporting system of ecology for human being. However, due to the high-speeddevelopment of economy, millions of tons of waste water are discharged in ocean andcontaminate the environment of ocean. The water exchange is very important for thecontrol of ocean pollution and environment protection. For sea bay such as Bohai Bay,the study of water exchange is a key factor that could give scientific evidence to thecontrol of ocean pollution. In this paper, a numerical method was used to compute thewater exchange. This paper developed two-dimension water dynamics model and two-dimensionadvection-diffusion model, the finite difference method ADI has been used to solvethe models. The software of the two models, the pre-process, the post-process andmoving display system have been established. The models were verified by theexperiment data of expand flow and field measured data of Bohai Bay, thecomputational result and experiment result agreed well. The mechanism of water exchange was studied in this paper. The water exchangemethods were collected and analyzed. The results of water exchange methods werecompared with results of the numerical modeling for different size sea bay. Theresults show that for these methods the larger size of the bay the more the error ofwater exchange rate. There for a numerical water exchange method that uses thehalf-exchange period to scale the water exchange ability was presented. The numerical modeling was used to calculate the water exchange of Bohai Bayand get the distribution of water exchange ability of Bohai Bay. The results show thatin some area the water exchange is very slow. At last, the particle movement and theadvection-diffusion movement of pollutant in Tianjin sea area were carried out.