One way to increase the precision of your calculations in Ansys Workbench is to use the double-precision solver option in Fluent. This option allows you to use more digits after the decimal point and reduce the numerical errors. You can find this option in the Fluent Launcher, under Options, as shown in this tutorial and this one. Alternatively, you can also increase the precision of values or number of decimal places in SpaceClaim by changing the Primary Precision option in File > SpaceClaim Options > Units. You can learn more about this option from this forum post.
How do I know if my calculations are precise enough?
There are several factors that can affect the precision of your calculations in Ansys Workbench, such as the mesh quality, the solver settings, the convergence criteria, and the material model. You can check the precision of your calculations by comparing the results with analytical solutions, experimental data, or other reliable sources. You can also monitor the residuals and other quantities of interest during the solution process to ensure that they reach a steady or periodic state. Additionally, you can perform a sensitivity analysis or a mesh refinement study to evaluate how the results change with different input parameters or mesh sizes. You can find more information and examples on how to check the precision of your calculations from the following sources:
Can you explain more about mesh quality and refinement study?
Mesh quality depends on several factors, such as the element type, the element shape, the element size, and the element alignment. Different types of elements have different advantages and disadvantages for different problems. For example, tetrahedral elements are easy to generate and can fit complex geometries, but they may have lower accuracy and stability than hexahedral elements. The element shape affects how well the element can approximate the curvature of the geometry and the gradients of the solution. The element size determines how fine or coarse the mesh is, and how well it can capture the details of the problem. The element alignment refers to how well the mesh follows the direction of the flow or the stress.
Mesh refinement is a way to improve the mesh quality by increasing the number of elements or changing their shape. Mesh refinement can be done globally or locally. Global mesh refinement applies to the whole domain or a large region, and it increases the resolution of the mesh uniformly. Local mesh refinement applies to a specific area of interest, such as a boundary layer, a corner, or a crack, and it increases the resolution of the mesh selectively. Mesh refinement can also be done adaptively or manually. Adaptive mesh refinement is an automated process that adjusts the mesh based on some criteria, such as the error estimate, the solution gradient, or the user-defined function. Manual mesh refinement is a user-controlled process that modifies the mesh based on some parameters, such as the element size, the inflation factor, or the smoothing factor.
Mesh quality and refinement study is important for obtaining reliable and accurate results in Ansys Workbench. A good quality mesh can reduce the numerical errors and improve the convergence of the solution. A refined mesh can capture the features and phenomena of interest more accurately and resolve the variations of the solution more precisely. However, mesh quality and refinement also have some trade-offs, such as increased computational cost, memory requirement, and solution time. Therefore, it is necessary to balance between mesh quality and refinement and computational efficiency.
You can learn more about mesh quality and refinement study in Ansys Workbench from these sources:
- Generating Mesh in ANSYS Workbench | Part-1
- How to check the MESH Quality in Ansys Workbench | Mesh Metrics | Skewness | Orthogonal Quality
- Tutorial on Meshing in ANSYS Workbench I ANSYS Basic Tutorials Apply various Mesh on geometry
- Ansys sturcutal analysis tutorials 23: mesh convergence and refinement ; Stress history plot
- mesh refinment study - Ansys Learning Forum
- Using Adaptive Convergence with Ansys Mechanical — Lesson 5
- MESH QUALITY AND ADVENCED TOPICS ANSYS WORKBENCH 16.0 - Academia.edu
How do I choose the right element size for my mesh?
Choosing the right element size for your mesh depends on several factors, such as the geometry, the physics, the accuracy, and the computational cost of your problem. There is no universal rule for selecting the optimal element size, but there are some general guidelines and methods that can help you. Here are some of them:
- You can start with a coarse mesh and refine it gradually until you reach a desired level of accuracy or convergence. You can use global or local refinement, adaptive or manual refinement, or a combination of them. You can also use different types of elements, such as tetrahedral, hexahedral, or hybrid elements, depending on the complexity and curvature of your geometry.
- You can use mesh sizing controls to specify the element size for a selected body, face, edge, or vertex. You can also use the sphere of influence option to apply a local element size around a point of interest. You can access these options by right-clicking on the Mesh in the project tree and selecting Insert > Sizing.
- You can use mesh metrics to evaluate the quality of your mesh, such as the skewness, the aspect ratio, the orthogonal quality, or the smoothness. You can check these metrics by right-clicking on the Mesh in the project tree and selecting Mesh Metrics. You can also use mesh statistics to see the number and type of elements in your mesh. You can access these statistics by right-clicking on the Mesh in the project tree and selecting Statistics.
- You can compare your results with analytical solutions, experimental data, or other reliable sources to validate your mesh. You can also monitor the residuals and other quantities of interest during the solution process to ensure that they are within acceptable limits. You can also perform a sensitivity analysis or a mesh convergence study to evaluate how your results change with different input parameters or mesh sizes.
You can learn more about how to choose the right element size for your mesh in Ansys Workbench from these sources:
- Correct mesh size - a quick guide! - Enterfea
- Learn Everything about the Ansys Workbench | Mesh Sizing - Skill-Lync
- Sizing a Mesh | Ansys Innovation Courses
- Defining Element Size Of A Body In ANSYS® Mechanical(Illustrated Expression) - ML
- Changing The Element Size In ANSYS® Meshing(Iluustrated Expression) - ML
How do I know if my element size is too small or too large?
The element size is a key parameter that affects the accuracy and efficiency of your mesh and solution in Ansys Workbench. If your element size is too small, you may have a very fine mesh that can capture the details of your problem, but it will also increase the computational cost, memory requirement, and solution time. If your element size is too large, you may have a very coarse mesh that can reduce the computational cost, memory requirement, and solution time, but it will also introduce numerical errors and affect the convergence of your solution.
To know if your element size is too small or too large, you can use some methods and criteria to evaluate your mesh and solution quality. Here are some of them:
- You can compare your results with analytical solutions, experimental data, or other reliable sources to validate your mesh and solution. You can also monitor the residuals and other quantities of interest during the solution process to ensure that they are within acceptable limits.
- You can use mesh metrics to evaluate the quality of your mesh, such as the skewness, the aspect ratio, the orthogonal quality, or the smoothness. You can check these metrics by right-clicking on the Mesh in the project tree and selecting Mesh Metrics. You can also use mesh statistics to see the number and type of elements in your mesh. You can access these statistics by right-clicking on the Mesh in the project tree and selecting Statistics.
- You can perform a sensitivity analysis or a mesh convergence study to evaluate how your results change with different input parameters or mesh sizes. You can use global or local refinement, adaptive or manual refinement, or a combination of them. You can also use different types of elements, such as tetrahedral, hexahedral, or hybrid elements, depending on the complexity and curvature of your geometry.
You can learn more about how to know if your element size is too small or too large in Ansys Workbench from these sources:
Can you explain more about the aspect ratio and orthogonal quality metrics?
Sure, I can explain more about the aspect ratio and orthogonal quality metrics in Ansys Workbench. These are two of the mesh metrics that you can use to evaluate the quality of your mesh elements.
The aspect ratio quantifies the shape of the elements, where 1 is a perfectly shaped element and the element shape is worse with a higher aspect ratio. The aspect ratio is defined as the ratio of the shortest length of the element to the longest length of the element1. For example, a tetrahedral element has an aspect ratio of 1 if it is a regular tetrahedron, and a higher aspect ratio if it is elongated or flattened. A hexahedral element has an aspect ratio of 1 if it is a cube, and a higher aspect ratio if it is a rectangular prism or a parallelepiped. The aspect ratio affects the accuracy and stability of the solution, as well as the convergence rate. Generally, you should aim for an aspect ratio less than 20 for structural analysis and less than 1000 for fluid analysis2.
The orthogonal quality quantifies the alignment of the elements with respect to the geometry and the physics of the problem. The orthogonal quality is defined as the minimum value of the dot product between the element face normal and the vector from the face centroid to the opposite node, for all faces of the element3. The orthogonal quality ranges from 0 to 1, where 1 is the best value and 0 is the worst value. For example, a tetrahedral element has an orthogonal quality of 1 if it is equilateral and orthogonal to the geometry, and a lower orthogonal quality if it is skewed or distorted. A hexahedral element has an orthogonal quality of 1 if it is aligned with the geometry and the flow or stress direction, and a lower orthogonal quality if it is misaligned or twisted. The orthogonal quality affects the accuracy and robustness of the solution, as well as the numerical diffusion and dispersion. Generally, you should aim for an orthogonal quality greater than 0.1 for most problems4.
You can check these metrics by right-clicking on the Mesh in the project tree and selecting Mesh Metrics. You can also use mesh statistics to see the number and type of elements in your mesh. You can access these statistics by right-clicking on the Mesh in the project tree and selecting Statistics.
You can learn more about how to improve these metrics by using different meshing methods, such as global or local refinement, adaptive or manual refinement, or different types of elements, such as tetrahedral, hexahedral, or hybrid elements. You can find some tutorials and examples from these sources:
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