用于浸入边界法的混合非结构网格的网格自适应
Mesh Adaptation on Hybrid Unstructured Meshes for Immersed Boundary Methods
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中文总结 AI 辅助
本研究开发了一种用于混合非结构网格的新型预处理工具，可对浸入几何周围的网格加密，通过圆柱、NACA0012翼型及多段翼型的流动模拟验证，结果与实验数据吻合良好，实现了准确高效的流动模拟。
中文摘要 AI 辅助
在本研究中，我们描述了一种用于混合非结构网格网格自适应的新型预处理工具，其目标应用是浸入边界法。该工具的输入是外部网格生成软件生成的非结构、混合且协调的网格，主要目标是在浸入几何周围对该网格进行加密，从而使采用浸入边界法的CFD求解器能够准确且高效地模拟流动问题。输入的背景网格可由不同类型的单元构成，如四面体、六面体、棱柱和棱锥，与笛卡尔网格不同，这些单元允许构建更灵活的网格。混合非结构网格使人们能够将浸入边界技术应用于一类新的流动问题，其中整个几何被分解为固定几何部分和变化几何部分：为固定几何生成贴体网格，而变化几何则采用浸入边界法。我们通过多个流动问题对新型网格进行测试，包括圆柱绕亚音速流动和NACA0012翼型绕亚音速流动，均采用有限体积法和间断伽辽金法求解Navier-Stokes方程。作为网格生成的工业实例，我们考虑多段翼型的模拟：在此情况下，网格生成软件为缝翼和主翼型生成非结构协调背景网格，而襟翼作为浸入几何放置在该贴体网格中。由于需要准确且高效的结果，我们在襟翼周围对该网格进行加密，随后采用耦合浸入边界法的有限体积法求解Reynolds平均Navier-Stokes方程，模拟高升力条件下的亚音速流动。所报道的数值模拟结果与实验数据吻合良好。
英文摘要
In this work, we describe a new preprocessing tool for mesh adaptation on hybrid unstructured meshes with a target application on immersed boundary methods. The tool has as input an unstructured, hybrid, and conforming mesh generated by an external mesh generation software, and the main goal is to refine this mesh around immersed geometries in such a way that the CFD solver using the immersed boundary method can simulate flow problems in an accurate and efficient manner. The input background mesh can be made of different types of elements, like tetrahedra, hexahedra, prisms, and pyramids, which, unlike Cartesian meshes, permit for a more flexible mesh. Hybrid unstructured meshes enable one to use the immersed boundary technology in a new class of flow problems where the full geometry is decomposed into a fixed geometry part and a changing geometry part. A body-fitted mesh is generated for the fixed geometry while for the changing one is used the immersed boundary method. We simulate several flow problems to test the new meshes, including subsonic flow past a cylinder and subsonic flow past an NACA0012 airfoil, both using finite volume and discontinuous Galerkin methods and solving the Navier--Stokes equations. As an industrial example of our mesh generation, we consider the simulation of a multi-element airfoil: in this case, a mesh generation software generates an unstructured conforming background mesh for the slat and main airfoil, while the flap is placed as immersed geometry in this body-fitted mesh. As accurate and efficient results are sought, this mesh is refined around the flap and then the subsonic flow at high-lift flow conditions is simulated with a finite volume method coupled with an immersed boundary method and using the Reynolds--averaged Navier--Stokes equations. The reported numerical simulations are in good agreement with experimental data.
