三维有限长圆柱绕流数值模拟

摘要

[目的]为探究有限长圆柱绕流的流动机理和特性,[方法]采用大涡模拟(LES)数值模型并结合涡识别方法,对三维有限长圆柱绕流进行数值模拟,并对有限长圆柱绕流进行验证和分析.[结果]模拟结果表明,有限长圆柱回流区相对较短,自由端的下洗作用会扰乱卡门涡街,导致阻力系数损失;相对于固定壁面,自由端面对顺流向速度影响更大;自由端面"蘑菇"涡成对出现,且存在2个流动源点;有限长圆柱流场存在更明显的三维特性,阻力系数更小;圆柱自由端后存在梢涡,圆柱与固定壁面交界处存在"马蹄"涡.[结论]所得结果可对有限长圆柱的流动特性进行相对全面的描述,对于理解和研究有限长圆柱绕流机理具有一定的参考价值.%[Objectives]In this paper,in order to study the flow characteristics and mechanism of three-dimensional flow around a circular cylinder of finite length,[Methods]a numerical simulation using a Large Eddy Simulation(LES)and vortex structural classification technology is carried out,and the accuracy of the simulation is proven.[Results]When analyzing the flow field,it is found that the length of the recirculation zone is smaller for a circular cylinder of finite length. In addition,the downstream from the free end can suppress the common phenomenon of Karman-Vortex-Street which leads to a loss of drag-coefficient. Compared with the fixed wall at the bottom,the free end surface has a higher influence on the onstream-wise velocity. The'mushroom' vortex appears in pairs and two original points exist on the free end.The circular cylinder of finite length appears to be strongly three-dimensional with a lower drag-coefficient.Moreover,there is a tip vortex behind the free end and a horseshoe vortex in the cylinder-wall junction.[Conclusions]The results of this paper give a relatively comprehensive description of the flow characteristics of a circular cylinder of finite length,and can provide useful references for relevant research.