Sewage Discharge In Coflowing Ambient And Calculation Method Study For Water Environmental Capacity

As a typical flowing type in hydrodynamics, the three-dimensional co-axial turbulent pure jet has getting more and more attention in environmental hydrodynamics field. In this thesis, the k~e turbulent model and hybrid finite analytic method are used to numerically analyze this type of flow.Firstly, the numerical model of turbulent jet in coflowing ambient (standard k~e model) is established, and calculation method (hybrid finite analytic method under the case of staggered grids) is introduced to be the base of our study.Secondly, we regard the co-axial jet in a rectangular transaction stream as subject investigated. Some conclusions are obtained as following: (1) The model's practicability is validated, by way of the comparisons of simulation results with experimental data, numerical values and theoretical analysis values. Prediction values to the smaller velocity ratio are given simultaneously. (2) Concentration field distributing characteristic and streamline characteristic are acquired. (3) The co-axial jet in quiescent ambient are primarily studied, and the comparison between numerical value and theoretical analysis value of concentration is achieved to demonstrate the model's validity. The maximum velocity's attenuation and therelation between sewage's dilution ratio S_c and distance x on centerline areattained.Finally, aiming at water environmental capacity's calculation problem, summary and analysis on the corresponding calculation methods in different cases are given, that is, contrary inducing method and subsection summation method under ascertain information condition, and blind theory calculation method under uncertainty information condition. After analysis and comparison, corresponding examples are presented.