3D Flow And Salinity Mathematic Model

Based on the detailed and abroad investigation of the inland and overseas literatures three dimensional turbulence computation in recent 10 years, the vertical delaminating coefficient kowas introduced in normal σ - coordinate transform in this paper. This means σ = wasused to displace the normal σ, which has been regularly used in the computation of 3D flow in recent years. The use of new σ coordinate is aimed to match the landform better and improve the instance that the normal σ coordinate mathematic models are emanative with complicated landform sometimes. The way to get ko was given in this paper. By this way, the turbulence control equations were constructed from Reynold equations with static pressure supposition and Boussinesq's turbulence viscidity coefficient supposition and the salinity transportation equations, which are representative of the matter transportation equations, are given. The integrated deduction and corresponding boundary conditions are also given. The potential problems related to the applications of k- model under the new coordinates are analyzed and the distribution formula of vertical turbulence viscidity coefficients is deduced on the base of logarithmic velocity of flow according to the characteristics of the model.The FDM is applied to the numeric discreteness of control equations under the new coordinates and the corresponding programs are developed. The reliability of the model is proved by the comparison between computation and observation in the following three cases, the distribution of vertical velocity of flow on two dimensional invariant flow, the distribution of vertical velocity of flow and transverse velocity of flow on three dimensional invariant flow in the flume. In the case of computation of invariant flow in the flume, the boundary conditions on bottom and wall of the flumes are managed specially according to the view of wall function method, and the formula about u* is deduced according to the hydraulic characteristic of invariant flow in the flume.In the part sea area of the Oujiang estuary which has complicated landform, the different ko are adopted in the control equations of flow and salinity process to work out the process of tide level, averaged salinity and the flow field using the invariant flow and the real process of tide level as the boundary conditions. The comparison and analysis among the computed results, the theoretic results and the computed results of two dimensional numeric model in a large area indicate that the model is applicable.The results are summed up deeply and systemically and the problems required further investigation are pointed out. Also, the promising approach is set forth and discussed initially.