Numerical Simulation On The Transport And Dispersion Of The Offshore Discharged Pollutants And Its Application

With the dense population and the rapid development of industrial, the plenty ofthe wastewater is increasing dramatically, including industrial and agriculturalwastewater, grows rapidly. Recently, discharging pollutants offshore becomes aneffective way to deal with pollutions in coastal cities. The pollutants are transported toocean area with a certain depth along pipes and discharged at a high speed bydiffusers. In order to avoid the pollutes staying around the offshore outfall, andinvading sensitive marine zone, such as the marine wetland areas, proliferative zonesand other serious problems, it is meaningful to study pollutants diluting, transportingand dispersion characteristics in the mixing zone of waster outfall, and to selectappropriate outfall location and establish effective wastewater discharge system.When studying the characteristics of the mixing zone of the pollute jet, twoaspects are taken into consideration. One of them is the near-field region of the jet,mainly affected by the jet’s initial momentum. The other is the far-field region of thejet, hardly independent of the jet, where pollutes are just to transport and diffuse whileflowing with the ambient water.This dissertation reviews the development of the studies on the dischargingpollutes in the near-field region of jets, and sums up the kinds of methods. Previousresearch mainly studied the jet in deeper water, but the research in the shallow waterlike Bohai Sea is rare, where the influence of the free surface on the hydrodynamicsand pollutants dispersal must be considered in the near-field region of jets. The modelof the near-field region of jets is established, including3-D turbulence model andwater quality model. the models are validated respectively using variousbenchmarks with analytical solutions and experimental datum. The results show thatthe model is credible and can be used to simulate the near-field region of pollutantsoutfalls.In the far-field region of jets, pollutants just passively transport and dispersealong with the ambient water. In this dissertation, FVCOM’s tidal model and waterquality model are used to simulate pollutes transport. The3-D FVCOM is analyzedand tested by the real datum in Bohai Bay. The results are proved that FVCOM canbe further applied to Bohai Bay to estimate pollutants transport.The validated3-D turbulent model and FVCOM are applied to NanGangindustrial area coastal water and used to study three pollutes outfalls. The initialdilutions in near-field regions of three jets are discussed, respectively. The concepts ofaverage concentration and affected area are suggested to be used to study the impact of pollutes in the DaGang proliferative zones, based on which reasonable location ofpollute outfall is decided.