Orthogonal quality is a mesh metric that measures the shape and orientation of the mesh cells. It is calculated by comparing the vectors from the cell centroid to the cell centroid of each adjacent cell, and to each face. The closer these vectors are to be orthogonal (perpendicular) to each other, the higher the orthogonal quality. Orthogonal quality ranges from 0 to 1, where 0 means poor quality and 1 means excellent quality ³.
Orthogonal quality is used for various purposes, such as:
- Assessing the convergence and accuracy of numerical methods, such as finite element analysis (FEA) or computational fluid dynamics (CFD).
- Optimizing the mesh size and shape for different applications and geometries.
- Detecting and correcting errors or defects in the mesh generation process.
Orthogonal quality can be improved by using structured meshes, which have more regular and balanced cell shapes than unstructured meshes. Structured meshes can also reduce the computational cost and time of solving complex problems. Some tools that can help create structured meshes are Multizone or Sweep mesh in ANSYS².
Source:
(1) Mesh Quality | Prescient Technologies. https://www.pre-scient.com/knowledge-center/product-development-by-reverse-engineering/mesh-quality/.
(2) What Are Good Orthogonal Quality Values? - Ansys Learning Forum. https://forum.ansys.com/forums/topic/what-are-good-orthogonal-quality-values/.
(3) Orthogonal Quality in ANSYS Meshing - Illustrated Explanation - ML. https://mechanicalland.com/orthogonal-quality-in-ansys-meshing/.
(4) ANSYS Mesh Metrics Explained - FEA Tips. https://featips.com/2022/11/21/ansys-mesh-metrics-explained/.
Why orthogonal quality is important in cfd analysis ?
Orthogonal quality is important in CFD analysis because it affects the accuracy and stability of the simulation results. Orthogonal quality measures how well the mesh cells are aligned with each other and with the geometry. If the mesh cells are not orthogonal, they can cause numerical errors or instability in the solution process. Therefore, it is desirable to have a high orthogonal quality for CFD simulations.
According to some sources, a good orthogonal quality value for Fluent is above 0.1¹². However, this may vary depending on the problem being solved and the element formulation. Some factors that can influence the orthogonal quality are:
- The shape and size of the mesh cells
- The capture curvature option
- The sweepable part of the geometry
- The meshing tool used
Some tools that can help improve the orthogonal quality are Multizone or Sweep mesh in ANSYS², which can generate structured meshes with more regular and balanced cell shapes. Structured meshes can also reduce the computational cost and time of solving complex problems.
Source:
(1) Mesh Quality | Mesh Visualization Tips | SimScale. https://www.simscale.com/docs/simulation-setup/meshing/mesh-quality/.
(2) What Are Good Orthogonal Quality Values? - Ansys Learning Forum. https://forum.ansys.com/forums/topic/what-are-good-orthogonal-quality-values/.
(3) finite element - Is mesh orthogonality important for FEM .... https://scicomp.stackexchange.com/questions/37355/is-mesh-orthogonality-important-for-fem.
(4) Determining Mesh Quality and Accuracy Parameters | System Analysis Blog .... https://resources.system-analysis.cadence.com/blog/msa2022-determining-mesh-quality-and-accuracy-parameters.
How do I calculate orthogonal quality of a mesh?
To calculate the orthogonal quality of a mesh, you need to compare the vectors from the cell centroid to the cell centroid of each adjacent cell, and to each face. The closer these vectors are to be orthogonal (perpendicular) to each other, the higher the orthogonal quality. Orthogonal quality ranges from 0 to 1, where 0 means poor quality and 1 means excellent quality ³.
There are different methods and tools that can help you calculate and improve the orthogonal quality of a mesh. For example, you can use MATLAB's meshQuality function ⁴ or ANSYS's Mesh Metrics ⁵ to evaluate the shape and orientation of the mesh cells. You can also use ANSYS's Multizone or Sweep mesh features ² to generate structured meshes with more regular and balanced cell shapes.
Source:
(1) Mesh Quality | Prescient Technologies. https://www.pre-scient.com/knowledge-center/product-development-by-reverse-engineering/mesh-quality/.
(2) Evaluate shape quality of mesh elements - MATLAB meshQuality - MathWorks. https://www.mathworks.com/help/pde/ug/pde.femesh.meshquality.html.
(3) ANSYS Mesh Metrics Explained - FEA Tips. https://featips.com/2022/11/21/ansys-mesh-metrics-explained/.
(4) Determining Mesh Quality and Accuracy Parameters. https://resources.system-analysis.cadence.com/blog/msa2022-determining-mesh-quality-and-accuracy-parameters.
(5) Lecture 7: Mesh Quality & Advanced Topics - FEA Tips. https://featips.com/wp-content/uploads/2021/05/Mesh-Intro_16.0_L07_Mesh_Quality_and_Advanced_Topics.pdf.
How to improve orthogonal quality of mesh on Ansys Workbench?
Orthogonal quality of mesh on Ansys Workbench is a measure of how well the mesh cells are aligned with each other and with the geometry. A high orthogonal quality means that the mesh cells are close to perpendicular to each other and to the faces. A low orthogonal quality means that the mesh cells are skewed or distorted, which can affect the accuracy and stability of the simulation results.
There are several ways to improve the orthogonal quality of mesh on Ansys Workbench, such as:
- Using structured meshes, which have more regular and balanced cell shapes than unstructured meshes. Structured meshes can be generated by using the sweep or multizone methods in Ansys Meshing ¹².
- Using inflation layers, which create smooth transitions from the boundary layer to the core mesh. Inflation layers can be applied to the geometry or to the mesh, depending on the mesh method used ³.
- Using mesh controls, such as face sizing, edge sizing, body sizing, sphere of influence, etc. to refine or coarsen the mesh in specific regions or features. Mesh controls can help capture the curvature and details of the geometry and reduce the faceting angles ⁴.
- Using mesh quality metrics, such as skewness, aspect ratio, smoothness, etc. to evaluate and improve the shape and orientation of the mesh cells. Mesh quality metrics can be accessed from the mesh tab or the statistics tab in Ansys Meshing ⁵.
Source:
(1) How to improve orthogonal quality in ANSYS Meshing?. https://forum.ansys.com/forums/topic/how-to-improve-orthogonal-quality-in-ansys-meshing/.
(2) Suggestions to improve mesh quality - Ansys Learning Forum. https://forum.ansys.com/forums/topic/suggestions-to-improve-mesh-quality/.
(3) Problems with mesh – elements impossible to accomplish Orthogonal Quality. https://forum.ansys.com/forums/topic/problems-with-mesh-elements-impossible-to-accomplish-orthogonal-quality/.
(4) Orthogonal Quality in ANSYS Meshing - Illustrated Explanation - ML. https://mechanicalland.com/orthogonal-quality-in-ansys-meshing/.
(5) Solver-Based Meshing: How To Maintain High-Quality Mesh - Ansys. https://www.ansys.com/blog/solver-based-meshing-how-to-maintain-high-quality-mesh.
(6) https://caeai.com/resources/tips-tricks-hex-brick-meshing-ansys-e-learning.
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