Numerical Prediction On Finite Length Line Inclined Positively Buoyant Jets In Uniform Cross Flows

Finite length inclined positively buoyant jets in uniform cross flows is one of basic flow shapes of environmental pollution. Numerical simulation on it is a supplement to the line buoyant jets in cross flow, and has a reference value to the hydraulic design, dilution effect and pollution range of diffusers.The emphasis of the thesis is put on the behaviors of the finite length inclined positively buoyant jets in uniform cross flow using Hybrid Finite Analytic Method (HFAM), the standard k - e turbulence model and staggered grid, and also some behaviors of jets at angles of 60"and 90?to the horizontal are compared. Many valuable conclusions make people have a definite cognition and comprehension to the finite length inclined positively buoyant jets in uniform cross flows from the work done in the thesis.In the first place, a brief description on the origin, the realistic background and researchful significance of the problem under study are presented, as well as the definitions and classifications of jets, review on the line buoyant jets are summarized. The changed density, turbulent, time-averaged, basic system of equations is derived from Boussinesq's approximation, which is given. The standard k-s model and the Hybrid Finite Analytic Method are introduced. Then, a series of successful numerical simulations on the finite length inclined positively buoyant jets in uniform cross flows environment are developed. Based on the results from numerical simulations, some qualitative pictures of the complex three -dimensional mean flows are given. In terms of these pictures, the flowing behavior of the buoyant jets and the mechanism of end-vortexes generation are made a study. The change rules of end-vortexes and temperature and dilution on trajectory of jets, horse-hoof shape of buoyant jets on horizontal, the phenomenon of the jets touch wall, and the effects of diffuser length^ densimetric Foroude number % velocity ratio on buoyant jets are also given. On the side, the result from the comparison between finite length inclined positively buoyant jets and finite length vertical positively buoyant jets is that inclined diffuser discharge is more advisable than vertical diffuser discharge in shallow water. At last, the thesis draws a conclusion from the whole research and takes a look into the forth-coming work on the line buoyant jets in cross flows.