To generate a good quality mesh for Ansys Fluent, you need to follow some essential rules that are based on the mesh quality criteria and the physics of the problem. Here are some of the rules:
- Choose the appropriate mesh type for your problem. Ansys Fluent supports different types of meshes, such as tetrahedral, hexahedral, polyhedral, and mosaic. Each type has its own advantages and disadvantages, depending on the geometry, flow features, and solver settings. For example, tetrahedral meshes are easy to generate and can conform to complex shapes, but they may have lower accuracy and stability than hexahedral meshes. Polyhedral meshes can reduce the cell count and improve the solution convergence, but they may require more memory and CPU time than tetrahedral meshes. Mosaic meshes can combine the benefits of polyhedral and hexahedral meshes by using polyhedral elements in the bulk and hexahedral elements near the walls¹.
- Minimize the mesh skewness and aspect ratio. Mesh skewness is a measure of how far a cell deviates from an ideal shape, such as an equilateral triangle or a regular hexagon. Mesh aspect ratio is a measure of how stretched a cell is. High skewness and aspect ratio can degrade the solution accuracy and convergence, as well as increase the numerical diffusion and errors. Ansys Fluent provides tools to check and report the mesh quality based on these criteria²⁴. You can also use mesh adaption and refinement techniques to improve the mesh quality in regions of high skewness or aspect ratio¹.
- Resolve the boundary layer and other flow features. The boundary layer is the thin layer of fluid near the wall where the velocity changes from zero to the free-stream value. The boundary layer has a significant impact on the drag, heat transfer, and separation of the flow. To capture the boundary layer effects accurately, you need to use a fine mesh near the wall that satisfies the y+ criterion. The y+ value is a dimensionless parameter that indicates how well the mesh resolves the viscous sublayer, which is the innermost part of the boundary layer where the flow is laminar. Depending on the turbulence model and the wall treatment used, you may need to have a y+ value below 1, between 1 and 5, or above 30¹. You can use Ansys Fluent to calculate and report the y+ values on your mesh². Besides the boundary layer, you also need to resolve other important flow features, such as shear layers, separated regions, shock waves, and mixing zones. You can use mesh sizing functions, inflation layers, or body of influence to control the mesh density and distribution in these regions¹.
- Optimize the mesh size and performance. The mesh size affects not only the solution accuracy, but also the computational cost and time. A finer mesh can resolve more details of the flow, but it also requires more memory and CPU time to solve. Therefore, you need to find a balance between the mesh resolution and the computational efficiency. You can use Ansys Fluent to estimate the memory and CPU time required for your mesh². You can also use parallel processing, hybrid meshing, or mesh morphing techniques to speed up your simulation¹.
These are some of the essential rules to generate a good quality mesh for Ansys Fluent. I hope this helps you with your simulation project 😊. If you want to learn more about Ansys Fluent meshing, you can check out some of these online courses³⁶ or read some of these documents⁴⁵. Have a nice day!
Source:
(1) Advanced Ansys Fluent Meshing | Ansys Training. https://www.ansys.com/training-center/course-catalog/fluids/advanced-ansys-fluent-meshing.
(2) Ansys Meshing | 2D/3D Mesh Generation and Analysis for FEA, CFD. https://www.ansys.com/products/meshing.
(3) ANSYS FLUENT 12.0 User's Guide - 6.2.2 Mesh Quality - ENEA. https://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/node167.htm.
(4) Ansys Fluent Meshing Learning Track | Ansys Courses. https://courses.ansys.com/index.php/learning-track/ansys-fluent-meshing-watertight-geometry-workflow/.
(5) How to Verify Mesh Quality in ANSYS Workbench - FEA Tips. https://featips.com/2021/05/07/how-to-verify-mesh-quality-in-ansys-workbench/.
(6) Chapter 15. Reporting Mesh Statistics - univ-reims.fr. https://romeo.univ-reims.fr/documents/fluent/tgrid/ug/chp15.pdf.
Cake Story
There was once a family of four: a father, a mother, a son, and a daughter. They loved to eat cake, but they had different preferences for the flavors and the toppings. The father liked chocolate cake with whipped cream, the mother liked vanilla cake with strawberries, the son liked carrot cake with cream cheese frosting, and the daughter liked lemon cake with blueberries.
One day, they decided to bake a cake together for their anniversary. They agreed to make a four-layer cake, each layer with a different flavor and topping. They spent hours in the kitchen, mixing, baking, cooling, and decorating the cake. They were very proud of their creation and couldn't wait to taste it.
They brought the cake to the dining table and admired it for a while. Then they decided to cut it into four equal pieces, one for each of them. The father took a knife and sliced the cake vertically, making two halves. Then he sliced one of the halves horizontally, making two quarters. He gave one quarter to himself and one quarter to his wife. He was about to slice the other half of the cake when he realized that he had made a mistake.
He had cut the cake in such a way that each piece had only one flavor and topping. His piece had only chocolate and whipped cream, his wife's piece had only vanilla and strawberries, and the remaining pieces had only carrot and cream cheese or lemon and blueberries. He had not mixed the flavors and toppings as they had intended.
He looked at his family and saw their disappointed faces. They had all wanted to try a bit of each flavor and topping, not just their own favorites. He felt sorry for ruining their anniversary cake. He apologized profusely and asked them what they wanted to do.
The mother thought for a moment and then smiled. She said that they could still enjoy the cake if they shared their pieces with each other. She suggested that they cut each piece into four smaller pieces, so that everyone could have one small piece of each flavor and topping. She said that this way, they could taste the variety of the cake and also appreciate each other's preferences.
The father agreed with his wife's idea and quickly cut the pieces as she suggested. He gave one small piece of each flavor and topping to each member of his family. They all thanked him and took their plates. They then proceeded to eat their cake with delight.
They found that the cake was delicious and that each flavor and topping complemented the others. They also enjoyed sharing their opinions and preferences with each other. They realized that they had learned something new about themselves and their family through this experience.
They finished their cake and hugged each other. They thanked each other for making the cake together and for being flexible and generous with their choices. They agreed that this was the best anniversary cake they ever had.
The end 😊
If U want more interesting posts go to links below
How to avoid overflow error in Ansys Fluent
Types of supports and examples - Ansys Static Structural
How to deal with peak stresses on Ansys Structural (Mechanical)
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