适用于涡激振荡问题研究的并行高精度方法

提出了一种用于研究大振幅及物体间小间距等极端情况下涡激振荡（VIV）问题的高精度方法。该方法针对三角形/四边形非结构混合网格，采用高精度谱差分（SD）格式对Navier-Stokes方程进行空间离散。通过引入非均匀滑移网格方法，将计算域分割成多个互相不重合的子区域，从而实现了子区域网格的独立变形，子区域之间通过粘接元进行信息传递。采用全耦合方法精确求解VIV问题中流体和固体间的相互作用。通过研究并行策略以及使用消息传递接口，实现了求解器的并行计算能力。数值模拟表明：对于无黏和有黏流动问题，该方法均能保持SD方法的高精度特性；对于动网格下的定常均匀来流，求解器能够做到自由流保持；单个圆柱VIV问题仿真与现有文献结果符合较好，验证了方法的可靠性；对于流场变形情况比较复杂的涡激振荡问题，求解器可以有效实现网格变形，并具有理想的并行效率。

A parallel high-order method for simulating vortex-induced vibrations

This paper presents a parallel high-order method for simulating Vortex-Induced Vibrations (VIV) at very challenging situations, such as vibrations of very closely placed solid objects or a row of multiple objects with large relative displacements. This method works on unstructured triangular/quadrilateral hybrid grids by employing the high-order Spectral Difference (SD) method for spatial discretization. By introducing nonuniform sliding meshes, a computational domain is split into several non-overlapping subdomains, and each subdomain can enclose an object and move freely with respect to its neighbors. The two sides of a sliding interface are coupled through a newly developed nonuniform mortar method. A monolithic approach is adopted to seamlessly couple the fluid and the solid vibration equations. Parallelization strategy is studied and achieved by message passing interface implementation. Through a series of numerical tests, we demonstrate that the present method is high-order accurate for both inviscid and viscous flows; for steady uniform flow, the solver can assure free stream preservation; single cylinder VIV simulation agrees well with previous simulations, which verifies the reliability of the method; mesh deformation can be easily applied even when the deformation of the flow field is complicated, and high parallel efficiency can be achieved at the same time.