Numerical Experiment on Two-Dimensional Line Thermal

查看全文 作　　者：[1]J.H.W.LEE;[2]陈国谦 机构地区：[1]Department of Civil Engineering,University of Hong Kong,Hongkong,China;[2]National Laboratory for Turbulence,Peking University,Beijing 100871,China 出　　处：《China Ocean Engineering》索引2002年第17卷第4期,共15页 基　　金：The project was supported by the Hong Kong Research Grants Council and in part by the Trans-Century Foundation for Outstanding Young Teachers sponsored by the National Education Ministry of China and a grant(No.1999043605)from the National 973 Projects o 摘　　要：The time evolution of a two-dimensional line thermal-a turbulent flow produced by an initial element with signifi-cant buoyancy released in a large water body, is numerically studied with the two-equation k - s model for turbulenceclosure. The numerical results show that the thermal is characterized by a vortex pair flow and a kidney shaped concentra-tion structure with double peak maxima; the computed flow details and scalar mixing characteristics can be described byself-similar relations beyond a dimensionless time around 10. There are two regions in the flow field of a line thermal: amixing region where the concentration of tracer fluid is high and the flow is turbulent and rotational with a pair of vortexeyes, and an ambient region where the concentration is zero and the flow is potential and well-described by a model ofdoublet with strength very close to those given by early experimental and analytical studies. The added virtual mass coeffi-cient of the thermal motion is found to be approximately 1. The aspect ratio for the kidney-shaped sectional thermal isfound to be around 1.45 for the self-similar phase. The predicted thermal spreading and mixing rate compares well withexperimental data. 关 键 词：thermals and puffs TURBULENCE modeling PLUMES and jets environmental fluid MECHANICS VORTEX flow added virtual mass MIXING and transport.