兰州大学机构库 >土木工程与力学学院
大涡模拟后台阶湍流流动及流场中颗粒的弥散
Alternative TitleResearch on LES of Turbulent Flow over a Backward-facing Step and Particle Dispersion in Flow Fields
刘晓军
Thesis Advisor武生智
2009-05-31
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Keyword大涡模拟 后台阶 弥散 有限体积法 离散颗粒
Abstract本文编制了一套二维湍流的计算机程序,可用于在交错网格系统下对后台阶湍流流动进行大涡模拟(LES)。在研究风场的大涡模拟方法中采用标准Smagorinsky亚格子模型,使用SIMPLER算法,对后台阶中的流动进行了数值计算。详细讨论了低雷诺数时涡结构回流区长度随不同台阶长度、不同入口条件的变化情况以及随时间的演化过程;分析了高雷诺数时的流场特征。这些结果与有关实验结果进行对比,吻合良好。 在此基础上,用轨道法模拟颗粒相运动。在研究气相大涡结构的基础上,重点揭示大涡结构下颗粒的运动规律及其弥散特性。研究表明小颗粒的分布受大涡结构的控制,其弥散过程与流体大涡结构的空间发展相一致,但是由于流动中大涡边缘和中心区的压力差,颗粒在大尺度涡的边缘出现密集。而大颗粒在流场中的分布受其惯性控制,对气相的涡结构不敏感。高速释放到流场中的大颗粒受惯性影响最大,保持在其原有动量方向上运动。 所得到了这些有益的结果,为在细观框架下研究气固两相相互作用奠定基础。
Other AbstractA general computer code has been developed for large eddy simulation(LES) of turbulent flow over a backward-facing step in a two-dimensional duct. For LES, the standard Smagorinsky sub-grid scale model and SIMPLER algorithm are applied to wind field simulation of backstep flow. For low Reynolds number, it is shown that the eddy coherent structures evolving in spatially with time increasing were visualized. The change of the reattachment length with different length of the step and different entrance conditions is also obtained. We also analyses the flow field characteristics with high Reynolds number. And comparison with experiment data is performed. On this base, the particle movement is simulated by orbital method. Based on research of wind field in large-eddy structure, it reveals the movement of particles and their dispersion in large-eddy structure. The study shows that, the dispersion process of small particles is dominated by the large eddy structure. Thus their distribution can trace the large eddy structures spatially. Due to the difference of pressure between the edge and the center of a large eddy structure, particles tend to congregate at the edge of large eddies. In contrast, the distribution of large particles mainly governed by inertia are relatively insensitive to large eddy. With high inflow velocity, large particles keep their motion in the direction of initial momentum. The useful results obtained lay the foundation for research gas-solid interaction under the micro framework.
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/226619
Collection土木工程与力学学院
Recommended Citation
GB/T 7714
刘晓军. 大涡模拟后台阶湍流流动及流场中颗粒的弥散[D]. 兰州. 兰州大学,2009.
Files in This Item:
There are no files associated with this item.
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Altmetrics Score
Google Scholar
Similar articles in Google Scholar
[刘晓军]'s Articles
Baidu academic
Similar articles in Baidu academic
[刘晓军]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[刘晓军]'s Articles
Terms of Use
No data!
Social Bookmark/Share
No comment.
Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.