Round Buoyant Jet In Three-dimensional Unsteady Flow Field Numerical Simulation Studies

Due to the effect of tide, the flow field is unsteady in coastal waters. The wastewater discharged into three-dimension dynamic flow, in fact, is diluted by the interaction of tide and jet flow. The concentration of pollutant in space depends on the characteristics of time averaged and turbulent flow. Because of the complexness of the co-existence of unsteady three dimensional environmental flow and the jet flow, thorough study of the problem is difficult. The study results of both numerical and experiment are very few. Numerical integral method is applied in this paper to study this problem, hoping to provide a reliable, yet simple numerical model for the application in the ocean disposal of waster water.Compared with other numerical model, momentum integral method is simple. The theoretical background is based on the self-similitude of the flow. In this method the governing differential equations are transformed into ordinary differential equations, using boundary conditions to make the mathematical problem closureThere are five parts in the paper:1. Introduction. The up-to-date research progress and application of buoyant jet is reviewed in this part. In view of the problem in the existing research results, the content and method are elaborated.2. Mathematical model. Based on some assumptions, a mathematical model is presented for a rounded buoyant jet flow in three-dimensional environmental water. The rounded buoyant jet is discharged into horizontally infinity water area. The jet flow is assumed as constant and fully turbulent, the environment water is uncompressible, and the pressure gradient is vertical.3. The result of numerical model. The ordinary differential equations are solved numerically under the given initial and other conditions. Based on the numerical results, the flow feature and the dilution development of the rounded buoyant jet in three-dimension dynamic flow are analyzed.4. Comparison with other model results and experimental data. The comparison is made with other numerical results and Hayakawa's experimental data. The comparison shows that the numerical results presented in this paper have better agreement with experimental data..5. Summary and expectation.In summary, the numerical model based on momentum integral method for solving the interaction problem of three dimensional flow and a jet flow is simple, yet reliable, and can be applied in the engineering practice of waster water ocean disposal.