阵列四柱绕流的数值模拟

Study on the characteristics of flow around a four square cylinder array

阵列四柱绕流特性是研究海洋结构物涡激运动的基础,文中引入雷诺平均法求解NS方程,结合SST k-ω湍流模型阵列四立柱绕流进行了数值模拟.根据中国南海流场实际分布特点,选取6个典型流速,由于阵列四柱结构对称,故选取3个来流方向进行研究.在对单个方柱绕流的斯特哈尔数与相关实验和数值模拟进行验证对比的基础上,研究了张力腿四立柱升力系数、拖曳力系数、立柱截面上的涡强分布以及尾涡泄放结构,采用频谱分析方法研究了阵列方柱频域特性.数值模拟结果表明:四立柱在0°及45°流向时四立柱的涡泄频率大于单方柱的涡泄频率,而22.5°时两者基本相同,四立柱的斯特哈尔数均大于单个立柱,各立柱涡强最大值均位于上游立柱迎流面拐点处,尾流涡泄结构均表现为2S模式.

The characteristics of flow around a four square cylinder array are the base of the research on the vor texinduced motion （VIM） of oceanic platform. Shearstress transport k to model （ SST k to model） of Reyn olds averaged NavierStokes equations （RANS） is employed to simulate the flow around four columns in this pa per. According to the real distribution characteristics of flow field in the South China Sea, six typical current ve locities are chosen in this paper. Three current directions are selected to simulate the flow＇s characteristics be cause of the platform＇s symmetry. The Strouhal number of flow around a square cylinder is compared with that of classical experiments and numerical simulations. Drag coefficient, lift coefficient, vortex intensity distribution of column crosssection and the vorticity structure of flow around four square cylinders are discussed. The frequency domain characteristics of square cylinders in array are studied by spectral analysis method. The results of numeri cal simulation show that the vortex shedding frequency of four square cylinders array is lager than that of a square cylinder at current direction 0°and current direction 45°, but almost the same at current direction 22.5°. It is found that Strouhal number of four square cylinders array is larger than that of a square cylinder. Meanwhile, the maximum point of vortex intensity of every column is at the corner of upflow surface. The structures of vortex shedding are all the 2S mode of vortex formation.