流固耦合分析的一种改进CBS有限元算法

A MODIFIED CBS FINITIE ELEMENT APPROACH FOR FLUID-STRUCTURE INTERACTION

针对流固耦合问题,发展了一种基于任意拉格朗日-欧拉(ALE)描述有限元法的弱耦合分区算法.运用半隐式特征线分裂算法求解Navier-Stokes方程,在压力Poisson方程中引入质量源项以满足几何守恒律;运用子块移动技术更新动态网格,并配以光滑处理防止网格质量下降;采用Newmark-β法求解结构运动方程.为保持流体-结构界面处速度和动量守恒,利用修正结合界面边界条件方法求解界面处速度通量和动量通量.运用本方法分别模拟了不同雷诺数下单圆柱横向和两向流致振动、串列双圆柱两向流致振动.计算表明,本文方法计算效率高,计算结果与已有实验和数值计算数据吻合.

This paper performed a finite element analysis of fluid-structure interaction （FSI） problems under the arbitrary Lagrangian-Eulerian （ALE） description. The loosely-coupled partitioned algorithm was employed where Navier-Stokes equations were solved by the semi-implicit characteristic based split （CBS） scheme while the equation of motion for structure was solved by the Newmark-/3 technique. A mass source term, in accordance with the so-called geometric conservation law （GCL） when computing on moving meshes, was adopted in the pressure Poisson equation, the efficient moving submesh approach （MSA） was used for the mesh deformation in the computation of fluid-structure interaction, and a smoothing algorithm was introduced to avoid the degradation of moving meshes if a long-playing simulation was carried out. Such a technique as modified combined interface boundary condition （MCIBC） method was applied on the velocity and momentum fluxes along the interface. Consequently, the present loosely-coupled partitioned procedure achieved better accuracy and stability on the study of fluid-structure interaction. Moreover, the proposed method was applied to the flow-induced vibration analysis of one single circular cylinder and two circular cylinders. The numerical results showed high efficiency and a good agreement with the existing experimental and numerical data.