基于LBM流固耦合算法的桥梁颤振稳定性分析

Numerical Investigation for Flutter Instability of Bridge Using FSI Model Within the Lattice Boltzmann Framework

为有效分析风-桥梁的相互作用和研究桥梁的颤振稳定性问题,发展了一种显式求解流固耦合问题的LBM数值模拟方法。将传统大涡模拟的亚格子涡黏性模型——动态Smagorinsky模型(dynamic Smagorinsky model,DSM)引入多松弛时间格式的格子玻尔兹曼方法(multiple relaxation time-lattice Boltzmann method,MRT-LBM)中,构造了一种显式运算的大涡模拟方法——MRT-LBM-DSM。采用MRT-LBM-DSM作为流场求解器;将结构视为弹性支撑于流场中的刚体,其运动方程采用Runge-Kutta法求解;利用格子玻尔兹曼方法(lattice Boltzmann method,LBM)的移动边界技术更新流固耦合面的位置,实现了流固耦合问题的松耦合分区显式求解。基于提出的LBM流固耦合算法,编制计算程序对Great Belt东桥的颤振稳定性进行分析。研究表明,由LBM流固耦合算法计算得到的Great Belt东桥颤振临界风速与试验和其他数值结论吻合良好,初步说明LBM流固耦合算法可以较为准确地预测颤振现象的发生。

In order to simulate wind-bridge interaction and study bridge flutter instability effectively,a lattice Boltzmann analysis of fluid-structure interaction( FSI) problems was presented. The flow around a rigid fixed bridge cross-section was modeled by large eddy simulation( LES) through incorporation of dynamic sub-grid-scale( SGS) model in multiple relaxation time lattice Boltzmann method( MRT-LBM). The time discretization of the structural dynamics was performed using Runge-Kutta method. The loosely-coupled partitioned algorithm was accomplished by updating fluid-structure interfaces via moving boundary technique of lattice Boltzmann method. In the end,the Great Belt East Bridge was investigated to study its flutter instability using self-developed codes. A good agreement was found between the simulation and the existing results regarding the critical flutter speed of Great Belt East Bridge. Moreover,the study showed that the present methodology has a well prediction for the onset of flutter instability.