應用於非結構化四邊形網格建構之輪廓撒點與網格品質改善技術發展

NCUIR > Engineering College > Graduate Institute of Mechanical Engineering > Electronic Thesis & Dissertation > Item 987654321/93717

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/93717

Title:	應用於非結構化四邊形網格建構之輪廓撒點與網格品質改善技術發展
Authors:	陳定輝;Chen, Ting-Hui
Contributors:	機械工程學系
Keywords:	六面體網格;網格品質改善;四邊形網格;自動化網格建構;平滑化;網格合併;輪廓節點建構;Hexahedral mesh;Mesh quality improvement;Quadrilateral mesh;Automated mesh construction;Smoothing;Mesh merging;Contour node construction
Date:	2023-07-11
Issue Date:	2024-09-19 17:32:18 (UTC+8)
Publisher:	國立中央大學
Abstract:	在進行模流分析之前，需要將CAD模型轉化為實體網格，以便在分析軟件中進行後續計算。目前，四面體網格發展較為成熟，應用較為普遍。但是，為了減少整體的網格數量，以達到減少計算時間的目的，需要構建六面體網格進行模流分析。而在生成六面體的實體網格之前，必須先建構四邊形的表面網格，然而生成高品質的四邊形網格仍然存在著許多的問題。本研究提出了一種考慮網格頂點相鄰關係的方法，來改善四邊形網格品質。首先，本研究使用B-rep結構的資料，對面上的各個輪廓邊進行分類，並透過分類結果進行均勻輪廓節點或是非均勻輪廓節點的建構。接著，應用本實驗室開發的網格自動建構技術進行網格生成，並在最後透過本研究開發的品質修復演算法，來改善網格的最終品質，其中包含平滑化以及網格合併等程序。最後，透過展弦比以及最小角度來評估生成的四邊形網格，並根據其結果進行分析，其中，所有測試案例中，99.8%的點可以正確輔助網格建構，而經過品質修復後，品質不好的網格占總體網格數量的不到1%，故證明本研究以正確的輔助網格的建構，並改善其網格品質使整體的網格品質優良。 ;Before performing mold flow analysis, it is necessary to convert the CAD model into a solid mesh for subsequent calculation in the analysis software. At present, the development of tetrahedral mesh is relatively mature, and its application is relatively common. However, in order to reduce the overall number of grids and achieve the purpose of reducing calculation time, it is necessary to construct a hexahedral grid for mold flow analysis. Before generating the hexahedral solid mesh, the quadrilateral surface mesh must be constructed, but there are still many problems in generating high-quality quadrilateral mesh. This study proposes a method that considers the neighbor relationship of mesh vertices to improve the quality of quadrilateral meshes. First, this research uses the B-rep structure data to classify each silhouette edge on the surface, and constructs uniform or non-uniform contour nodes through the classification results. Then, apply the mesh automatic construction technology developed in this laboratory for mesh generation, and finally use the quality restoration algorithm developed in this research to improve the final quality of the mesh, including smoothing and mesh merging procedures. Finally, the generated quadrilateral mesh is evaluated by aspect ratio and minimum angle, and analyzed according to the results. In all test cases, 99.8% of the points can correctly assist mesh construction, and after quality repair, the quality is not good. Good grids account for less than 1% of the total number of grids, so it is proved that this research uses correct auxiliary grid construction and improves its grid quality to make the overall grid quality excellent.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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