The fluid-flexible-structure interaction (FFSI) is characterized by the large deformation, the thin structure, and the complex turbulent flow field. Accurately simulating FFSI poses three challenges, which are the modeling of the thin structure, the capture of moving interface, and the numerical stability of multi-physics field coupling, respectively. In this study, the FFSI is simulated by the entirely smoothed particle hydrodynamics (SPH) because of its natural advantage in dealing with the moving interface within a unified framework. The shell model with single-layer particles is introduced into SPH to simulate the thin flexible structure. The truncation error caused by the single-layer boundary is modified by the normal flux approach. The - turbulence model is incorporated into SPH to improve numerical accuracy in capturing turbulent details. In addition, other techniques or models that ensure the efficiency and stability of the calculation are used in this study, including PST (particle shifting technique), δ-SPH model, and GPU (graphics processing unit). The flows around the single filament and the hydrostatic benchmark are simulated to verify the accuracy of the current SPH method for simulating FFSI. The interaction between fluid and single filament and the interaction between fluid and dual-filament system are simulated to study the interacting mechanism between fluid and flexible structures. Three important conclusions are obtained by the discussions of numerical results: the critical values of dimensionless parameters can be found to determine whether the filament vibration attenuates or tends to stabilize; the stabilization time of the filament movement can be effectively reduced as the initial orientation angle increases or the perturbation of upstream flow field increases; the movement of filament with a small mass ratio is more sensitive to the perturbation of upstream flow field.

中文翻译：

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完全基于SPH的FSI求解器及超薄柔性结构水动力特性数值研究


流体-柔性-结构相互作用（FFSI）具有变形大、结构薄、湍流场复杂等特点。精确模拟 FFSI 面临三个挑战，分别是薄结构的建模、运动界面的捕获以及多物理场耦合的数值稳定性。在本研究中，FFSI 采用完全平滑的粒子流体动力学（SPH）进行模拟，因为它在统一框架内处理运动界面方面具有天然的优势。 SPH中引入单层粒子壳模型来模拟薄型柔性结构。由单层边界引起的截断误差通过法向通量方法进行修正。 - 湍流模型被纳入 SPH 中，以提高捕捉湍流细节的数值精度。此外，本研究还使用了其他保证计算效率和稳定性的技术或模型，包括PST（粒子移位技术）、δ-SPH模型和GPU（图形处理单元）。对单丝周围的流动和静水压基准进行了模拟，以验证当前 SPH 方法模拟 FFSI 的准确性。通过模拟流体与单丝之间的相互作用以及流体与双丝系统之间的相互作用，研究流体与柔性结构之间的相互作用机制。 通过数值结果的讨论得到了三个重要结论：可以找到无量纲参数的临界值来确定灯丝振动是否衰减或趋于稳定；随着初始取向角的增大或上游流场扰动的增大，可以有效减少细丝运动的稳定时间；质量比小的细丝运动对上游流场的扰动更加敏感。