网格变形与重叠相结合的运动边界问题数值模拟方法研究

Overlap mesh as well as deforming mesh are the two main methods dealing with moving boundary problems. On the one hand, overlap mesh is good at dealing with multi-body moving problems, however, it can not handle morphing boundary. On the other hand, deforming mesh method, which can solve morphing boundary problems perfectly, would meet great difficult when handling severe multi-body relative moving problems. Although the local re-mesh step can be used to enhance the ability of deforming mesh, the procedure used to be very complex and the effect are not always satisfying. Therefore, the combination of the overlap mesh and deforming mesh should be more beneficial. In this project the coupled scheme of the overlap mesh and deforming mesh is taken into account, the main research fields contains: First, the robust and effective deforming mesh method. Second, conservative interpolation method in overlap region. Third, coupled strategy of the overlap mesh and deforming mesh. Fourth, unsteady flow solver based on the coupled moving mesh. This coupled method can deal with issues with both morphing and large relative moving, which would be more adaptive compared with the traditional overlap mesh as well as deforming mesh.

变形网格技术和重叠网格技术是处理运动边界问题常见的两种方法。重叠网格技术在处理多体相对运动问题时具有突出的优势，但是无法处理柔性变形问题；网格变形技术则能够处理中等柔性变形问题，通过结合局部网格重构，也可以应用于大变形、大位移、相对运动问题，但是局部网格重构操作过程繁琐，对于相对运动比较剧烈的问题计算效率、精度受影响较大。因此，将网格重叠、网格变形相结合是一个较好的动网格策略。本项目拟开展网格变形\重叠相结合的动态混合网格技术及非定常数值计算方法研究，内容包括鲁棒、高效的网格变形技术研究，重叠网格守恒插值技术研究，网格变形\重叠耦合方法研究，与该耦合动网格策略相适应的非定常数值计算方法研究等。该耦合方法能够适用于既存在柔性变形、又存在剧烈相对运动的复杂工程问题的数值研究，和单纯的重叠网格或者变形网格技术相比，其具有更优越的应用前景。

变形网格技术和重叠网格技术是处理运动边界问题常见的两种方法。重叠网格技术在处理多体相对运动问题时具有突出的优势，但是无法处理柔性变形问题；网格变形技术则能够处理中等柔性变形问题，通过结合局部网格重构，也可以应用于大变形、大位移、相对运动问题，但是局部网格重构操作过程繁琐，对于相对运动比较剧烈的问题计算效率、精度受影响较大。因此，将网格重叠、网格变形相结合是一个较好的动网格策略。.本项目在自然基金项目的支持下，开展了网格变形与重叠相结合的动态混合网格技术及非定常数值计算方法研究，发展了并行化的非结构重叠网格隐式装配技术、并行化的网格变形技术，并在统一的框架下实现了网格重叠与变形的结合。该耦合方法能够适用于既存在柔性变形、又存在剧烈相对运动的复杂工程问题的数值研究，和单纯的重叠网格或者变形网格技术相比，其具有更优越的应用前景。此外，该技术具有良好的并行加速比，针对多体嵌套问题的测试表明，其并行效率与美国的PUNDIT软件相当。基于该技术，进一步发展了考虑动态重叠网格的多学科紧耦合数值模拟方法，形成了气动/运动/控制一体化数值模拟能力，并在生物外流流体力学研究、多体分离、数值虚拟飞行等方面得到了有效应用。