A high‐order element based adaptive mesh refinement strategy for three‐dimensional unstructured grid. (29th June 2017)

• Record Type: Journal Article
• Authors: Gou, Jinlan; Yuan, Xin; Su, Xinrong
• Is Part Of: International journal for numerical methods in fluids. Volume 85:Number 9(2017)
• Page Start: 538
• Page End: 560
• Publication Date: 2017-06-29
• Subjects: accuracy -- AMR -- curved geometry -- high‐order element -- hybrid unstructured mesh -- robustness; Fluid dynamics -- Mathematics -- Periodicals; 532
• DOI: 10.1002/fld.4397
• Languages: English
• ISSNs: 0271-2091

Abstract

Summary: Adaptive mesh refinement (AMR) shows attractive properties in automatically refining the flow region of interest, and with AMR, better prediction can be obtained with much less labor work and cost compared to manually remeshing or the global mesh refinement. Cartesian AMR is well established; however, AMR on hybrid unstructured mesh, which is heavily used in the high‐Reynolds number flow simulation, is less matured and existing methods may result in degraded mesh quality, which mostly happens in the boundary layer or near the sharp geometric features. User intervention or additional constraints, such as freezing all boundary layer elements or refining the whole boundary layer, are required to assist the refinement process. In this work, a novel AMR strategy is developed to handle existing difficulties. In the new method, high‐order unstructured elements are first generated based on the baseline mesh; then the refinement is conducted in the parametric space; at last, the mesh suitable for the solver is output. Generating refined elements in the parametric space with high‐order elements is the key of this method and this helps to guarantee both the accuracy and robustness. With the current method, 3‐dimensional hybrid unstructured mesh of huge size and complex geometry can be automatically refined, without user intervention nor additional constraints. With test cases including the 2‐dimensional airfoil and 3‐dimensional full aircraft, the current AMR method proves to be accurate, simple, and robust. Abstract : This paper analyzes the failures of existing unstructured adaptive mesh refinement (AMR) strategy and proposes a novel high‐order element–based AMR strategy for hybrid unstructured grid. The results show that this is an accurate and robust AMR for 3‐dimensional hybrid unstructured mesh of huge size and complex geometry, without user intervention and additional contraints.