Improvements in the reliability and quality of unstructured hybrid mesh generation

Ito, Yasushi; Nakahashi, Kazuhiro

doi:10.1002/fld.669

Cited by 95 publications

(40 citation statements)

References 26 publications

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“…As the unstructured mesh generator and flow solver, Tohoku University Aerodynamic Simulation (TAS) code 8,9) is used in this study. RANS equations are solved in the unstructured mesh using a cell-vertex finite volume method.…”

Section: Flow Solver and Turbulence Modelmentioning

confidence: 99%

CFD Validation for High-Lift Devices: Three-Element Airfoil

Murayama

Zhong

Mukai

et al. 2006

Trans. Japan Soc. Aero. S Sci.

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In this study, the accuracy of structured and unstructured mesh CFD codes in simulating the flow around a threeelement high-lift configuration (slat, main wing, and flap) is assessed, and mesh dependency and effect of turbulence models are studied. In the first part of the study, the results of two structured mesh CFD codes and an unstructured mesh CFD code using the same turbulence model are compared and discussed. A mesh refinement approach is also used to examine the dependency of numerical accuracy on the density of unstructured meshes. By properly distributing mesh points in an unstructured mesh, the detail in flow physics is obtained. It is also shown that the quantitative prediction of the vortex in the slat cove is an important factor that affects accuracy. In the second part of the study, three turbulence models are compared using one of the structured mesh CFD codes. All turbulence models can produce similar flowfields. However, several differences are seen in the separated regions, especially in the slat cove. Commonly used turbulence models, Spalart-Allmaras model and Menter's SST model, produce similar aerodynamic forces at lower angles of attack. At higher angles of attack, the SST model gives better results for the present computations. It is found that the maximum lift and the angle at which the stall occurs are very sensitive to the turbulence model.

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Section: Flow Solver and Turbulence Modelmentioning

confidence: 99%

CFD Validation for High-Lift Devices: Three-Element Airfoil

Murayama

Zhong

Mukai

et al. 2006

Trans. Japan Soc. Aero. S Sci.

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“…Mesh sizes h 1 , h 2 , h 3 are defined for every point of the volume in each of the directions d 1 , d 2 , d 3 . In this paper, the mesh size field at a point x is isotropic, i.e.…”

Section: Cross Fieldsmentioning

confidence: 99%

A frontal approach to hex-dominant mesh generation

Baudouin

Remacle

Marchandise

et al. 2014

Adv Model Simul Eng Sci

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Background: Indirect quad mesh generation methods rely on an initial triangular mesh. So called triangle-merge techniques are then used to recombine the triangles of the initial mesh into quadrilaterals. This way, high-quality full-quad meshes suitable for finite element calculations can be generated for arbitrary two-dimensional geometries. Methods: In this paper, a similar indirect approach is applied to the three-dimensional case, i.e., a method to recombine tetrahedra into hexahedra. Contrary to the 2D case, a 100% recombination rate is seldom attained in 3D. Instead, part of the remaining tetrahedra are combined into prisms and pyramids, eventually yielding a mixed mesh. We show that the percentage of recombined hexahedra strongly depends on the location of the vertices in the initial 3D mesh. If the vertices are placed at random, less than 50% of the tetrahedra will be combined into hexahedra. In order to reach larger ratios, the vertices of the initial mesh need to be anticipatively organized into a lattice-like structure. This can be achieved with a frontal algorithm, which is applicable to both the two-and three-dimensional cases. The quality of the vertex alignment inside the volumes relies on the quality of the alignment on the surfaces. Once the vertex placement process is completed, the region is tetrahedralized with a Delaunay kernel. A maximum number of tetrahedra are then merged into hexahedra using the algorithm of Yamakawa-Shimada. Results: Non-uniform mixed meshes obtained following our approach show a volumic percentage of hexahedra that usually exceeds 80%. Conclusions: The execution times are reasonable. However, non-conformal quadrilateral faces adjacent to triangular faces are present in the final meshes.

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“…NASTRAN TM [16] which is a high-fidelity commercial software is employed for the structural and aeroelastic evaluations. Besides, the in-house unstructured mesh solver named as TAS-Code [17,18] gravity of the fuselage-wing configuration.…”

Section: Evaluation Methodsmentioning

confidence: 99%

Knowledge Discovery for Transonic Regional-Jet Wing through Multidisciplinary Design Exploration

Chiba

Obayashi

Morino

2008

JAMDSM

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Data mining is an important facet of solving multi-objective optimization problem. Because it is one of the effective manner to discover the design knowledge in the multiobjective optimization problem which obtains large data. In the present study, data mining has been performed for a large-scale and real-world multidisciplinary design optimization (MDO) to provide knowledge regarding the design space. The MDO among aerodynamics, structures, and aeroelasticity of the regional-jet wing was carried out using high-fidelity evaluation models on the adaptive range multi-objective genetic algorithm. As a result, nine non-dominated solutions were generated and used for tradeoff analysis among three objectives. All solutions evaluated during the evolution were analyzed for the tradeoffs and influence of design variables using a selforganizing map to extract key features of the design space. Although the MDO results showed the inverted gull-wings as non-dominated solutions, one of the key features found by data mining was the non-gull wing geometry. When this knowledge was applied to one optimum solution, the resulting design was found to have better performance compared with the original geometry designed in the conventional manner.

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Improvements in the reliability and quality of unstructured hybrid mesh generation

Cited by 95 publications

References 26 publications

CFD Validation for High-Lift Devices: Three-Element Airfoil

CFD Validation for High-Lift Devices: Three-Element Airfoil

A frontal approach to hex-dominant mesh generation

Knowledge Discovery for Transonic Regional-Jet Wing through Multidisciplinary Design Exploration

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