In this work, the sharp-interface immersed boundary (IB) method proposed by Mittal et al. (J Comput Phys 227(10):4825–4852, 2008) is extended to fluid-structure-interaction (FSI) simulation of parachute inflation by utilizing several open-source tools. The method employs a Cartesian-grid ghost-cell methodology to accurately represent the immersed boundary, and it is suitable for solving moving-boundary flows with arbitrarily complex geometries. The finite-element code CalculiX is employed to solve the structural dynamics of the parachute system. The IB flow solver is coupled with CalculiX in a minimally-invasive manner using the multi-physics coupling library preCICE. The implicit fluid-structure coupling together with the Aitken adaptive under-relaxation scheme is considered to improve the numerical accuracy and stability. The developed approach is validated by a benchmark FSI case. Numerical experiments on the inflation process of several typical parachutes are further conducted. The breathing process, flow structure, canopy displacement and drag coefficient are analyzed to demonstrate the applicability of the present approach for simulating parachute inflation.

中文翻译：

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锐界面浸入边界法模拟降落伞充气的扩展

在这项工作中，Mittal 等人提出的锐界面浸入边界（IB）方法。 (J Comput Phys 227(10):4825–4852, 2008) 通过利用多种开源工具，扩展到降落伞膨胀的流固耦合 (FSI) 模拟。该方法采用笛卡尔网格幻影单元方法来精确表示浸没边界，适用于求解具有任意复杂几何形状的移动边界流。有限元代码 CalculiX 用于求解降落伞系统的结构动力学。 IB 流求解器使用多物理场耦合库 preCICE 以微创方式与 CalculiX 耦合。考虑了隐式流固耦合和 Aitken 自适应欠松弛方案来提高数值精度和稳定性。所开发的方法已通过基准 FSI 案例进行验证。进一步对几种典型降落伞充气过程进行了数值实验。对呼吸过程、流动结构、座舱盖位移和阻力系数进行了分析，以证明该方法对于模拟降落伞充气的适用性。