A Numerical Simulation Of The Transport Of Suspended Particulate Matter In The 3-D Tidal Current Field

In this paper a 3-D particle tracing model is set up to simulate the transport of suspended particulate matter,e.g. drilling chips,slurry and suspended sand that comes into existence during oilfield development. Not only convection but also random diffusion of substantial particle and their sediment are considered in the model. In the model, particles which have different particle size have different subsidence velocities. And more over, the sedimentary condition and resuspension process of the suspended particle are taken into account in the model. Using this particle tracing method,we can get the sites of every suspended particles in the 3-D space.Finally, statistics method is applied to get the space-time distribution of the suspended particles concentration.The suspended substances moving with seawater nearby is regarded as particulate groups,and they can be traced in the tidal current field. Every particle movement is divided into three processes.The first process is convection forced by tidal current field. The second process is the turbulent diffusion analogued by random movement. The third process is the sediment and resuspension process of particles. After the three processes the next positiones of particles are localized. And finally,the concentration of these suspended particles is obtained after the mass of particles in the cell is added.When the particle tracing model are applied in the practicle sea area that is the South China Sea, a 3-D tidal current field is simulated based on the Backhaus model firstly. The result is going to be inputted to the suspended matter transport model.and then,three cases that is point source instantaneous discharge,point source continuous discharge and moving source continuous discharge are simulated respectively.And moreover,the differences of the calculation results in the following three cases are compared.In the case of point source instantaneous discharge, uniformity random distribution and normality random distribution are applied respectively to simulate the particulate diffusion process. In the case of point source continuous discharge for 5 hours,the particles are discharged respectively at the instance of high tide and low tide. In the case of moving source continuous discharge for 5 hours,the different computing formula to calculate the sediment velocity of particles are applied to simulate the sedimental process. The result indicates that the numerical simulation method of calculating concentration by tracing- statistics particles is feasible if advisable diffusion coefficient is obtained,and reasonable computing formula for getting the sediment velocity is applied.