Numerical Simulation Of Soluble Conservative Pollution Diffusion In Rivers Using SWE-SPH Method

With economic development,a large amount of industrial and urban residential waste water enters rivers and lakes through the sewage outlet,causing the environmental quality of the water area near the sewage outlet to decline,study the law of the transport and diffusion of pollutants,and accurately conduct the transmission behavior of the pollutants in the river.Forecast,it provides scientific guidance basis for the treatment of pollutants in rivers and lakes.In this paper,the Shallow water equation-Smoothed particle hydrodynamics(SWE-SPH)method is used to solve the shallow water equation and corresponding moving diffusion equation,the depth average(?)-(?)turbulence equation and the corresponding turbulent diffusion equation to simulate the soluble inert pollutants diffusion process in the river.For the first time,the SPH method was used to solve the deep average(?)-(?)turbulence equation,and the preliminary exploration of the turbulent diffusion process of pollutants was carried out,and the application field of the SPH method was further expanded.The main research work is as follows:1.Establish the SWE-SPH diffusion model,and develop the open source code for SPH solving shallow water to simulate and verify the molecular diffusion and migration diffusion process of pollutants in one-dimensional and two-dimensional shallow water.Design instantaneous point sources,finite distribution sources and continuous distribution sources and other different types of pollution sources,and compare and verify that the SPH simulation values are consistent with the analytical solution results.2.Use the SWE-SPH method to solve the depth average(?)-(?)turbulence equation,verify the hydrodynamics,and simulate the turbulent motion process of the constant flow in the two-dimensional complex rough river bed and the sudden expansion channel on the smooth river bed.The simulation results are the same as the experimental values in the literature.The comparison between the simulated values is high,and the error of the numerical calculation results is small.3.Simulate the turbulent diffusion process of pollutants in actual rivers,preset the COD concentration of 8 kg/m~3 to be instantly discharged into the Ningxia section of the Yellow River during high and low water periods,and study the distribution of pollutant concentrations over time within a section of14 km from the accident site.Under the same discharge conditions,the water quality pollution in the river during the dry season is more serious,and the simulation results are reasonable,verifying that the SWE-SPH method is reliable for solving the pollutant transport equation,and there is no negative concentration value in the calculation process,and the stability is good.