Abstract A flapping motion is an important fluid–structure interaction (FSI) phenomenon. Although it has been extensively studied, there are still many unknowns. Because there are numerous parameters in the kinematics and morphology for flapping motions, it is difficult to experimentally determine parameter values that enhance flapping aerodynamics because of the associated time, cost, and space constraints. Therefore, a simulation-based study is a promising approach for investigating flapping motions. In our previous work, we developed an interface-tracking-based three-dimensional (3D) parallel FSI analysis system by the partitioned iterative method. However, this system failed in some cases during parametric calculations for various flapping motions. This seems because of 3D large movements and complex twisting motions of a deformable flapping wing. Because the distortion of a fluid mesh often leads to failure in the FSI analysis, the selection of a mesh control scheme greatly influences the robustness. Improving the robustness of the analysis is essentially important for the parametric analyses with a wide range of parameter sets to be tested. In the present study, we incorporate the solid-extension mesh moving technique (SEMMT) together with a specialized mesh design surrounding the flapping wing into our analysis system to improve the robustness. Furthermore, we quantitatively demonstrate the effectiveness of the above mesh control technique in 3D flapping problems by measuring the degree of mesh distortion. Using the improved FSI analysis method, we have succeeded in conducting wide range parametric studies of flapping motions to compare active and passive pitch motions and investigate lead-lag motions. We found that passive pitch caused due to appropriate Young's modulus in an elastic portion was able to produces a high lift coefficient which was almost equivalent to active pitch cases. We also confirmed that some lead-lag motions enhance the lift force.

中文翻译：

---

用于扑翼运动参数研究的鲁棒流固耦合分析

摘要 扑动是一种重要的流固耦合（FSI）现象。尽管已被广泛研究，但仍有许多未知数。由于扑动运动的运动学和形态学参数很多，由于相关的时间、成本和空间限制，很难通过实验确定增强扑动空气动力学的参数值。因此，基于模拟的研究是研究扑翼运动的一种很有前景的方法。在我们之前的工作中，我们通过分区迭代方法开发了一个基于界面跟踪的三维 (3D) 并行 FSI 分析系统。但是，在某些情况下，该系统在对各种扑翼运动进行参数计算时会失败。这似乎是因为可变形扑翼的 3D 大运动和复杂的扭曲运动。由于流体网格的变形往往会导致 FSI 分析失败，因此网格控制方案的选择对鲁棒性影响很大。提高分析的稳健性对于要测试的参数集范围很广的参数分析至关重要。在本研究中，我们将实体扩展网格移动技术 (SEMMT) 与围绕扑翼的专门网格设计结合到我们的分析系统中，以提高稳健性。此外，我们通过测量网格失真程度，定量证明了上述网格控制技术在 3D 拍打问题中的有效性。使用改进的 FSI 分析方法，我们成功地对扑动运动进行了广泛的参数研究，以比较主动和被动俯仰运动并研究超前-滞后运动。我们发现由于弹性部分中适当的杨氏模量引起的被动俯仰能够产生高升力系数，这几乎相当于主动俯仰情况。我们还确认了一些超前滞后运动会增强升力。