基于LBM流固耦合算法的桥梁颤振稳定性分析

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，在MRT-LBM框架下构造了一种显式运算的大涡模拟方法—MRT-LBM-DSM作为流固耦合算法的流场求解器；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求解。基于LBM流固耦合算法编制计算程序对Great Belt东桥的颤振稳定性问题进行了分析。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。

Numerical Investigation for Flutter Instability of Bridge using FSI Model within the Lattice Boltzmann Framework

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.