06 Dec How to spot poor quality mesh zones (revisited and improved)
Dealing with complex geometries can be difficult. Creating good meshes for CFD simulations is sometimes a very complex task. It is not unusual that, especially in the very first simulations trials, the computational grid is affected by numerous problems. In such cases it is fundamental to refine the grid in order to eliminate these shortcomings and to improve the overall quality. In this post we present a tool provided by CONSELF which allows the user to identify poor quality mesh zones in a very intuitive way.
Mesh geometric problems and how to spot them
Geometric problems can often be encountered when dealing with computational grids creation. They are typically caused by a combination of multiple factors:
- Complex input geometries
- Too few cells
- Inappropriate meshing algorithm/features
It is important to have a clear idea of these errors, why they affect solution accuracy and their relation with cells geometry. The image on the right shows four typical meshing shortcomings, we accurately described them in one of our previous posts: “4 mesh issues causing poor CFD simulation accuracy”
There are other mesh issues that can affect the computational grid. All these problematic zones can be located in different areas of the simulation domain so a graphical way to identify such areas is the best instrument to help the user to deal with them. In fact, in order to tackle these critical elements the first thing to do is to isolate them, to know where they are.
How to improve your grid
We are now able to spot zones with poor mesh quality parameters. The image on the left shows you how your grid will look like when problematic cells are highlighted. What can we do next?
In order to improve the quality of our discretization, the classical countermeasure, that works most of the times, is to refine the grid in those particular regions. This way we will be able to better describe geometry features that are one of the most common factors causing poor mesh quality.
It is also possible to try a different meshing algorithm that can be more suitable for the given geometry. In addition, if we are using a particular feature such as the boundary layer, we have to be really careful. Such features must be used only when the combination geometry complexity / meshing resolution assures an adequate topology for smooth layers growth/extrusion.
“With CONSELF is very easy to find poor quality mesh zones, I am able to discover problematic areas even before running my simulation”
How to spot poor quality mesh zones: the video tutorial
The tutorial video on the right shows you how to take advantage of CONSELF to locate mesh issues in your simulation domain. When you are about to setup a simulation, the first thing to check is if your mesh presents poor quality zones or not. To do so follow these are these steps:
- Choose the mesh you want to use
- Let the mesh load in the graphical window and:
- open the menu clicking on the “Pipeline” button
- select the solution file “system.foam”
- check if under the menu “Color” you have only “Solid color” or additional options (typical mesh quality parameters such has nonOrthoFaces, skewFaces, etc)
In case you see only “Solid color” it means your mesh does not present problems and you can proceed with your simulation. Otherwise, you should check where your problems are located. To do so, use following procedure:
- In the graphical window
- apply the “Threshold” filter under the menu identified by a “+” sign
- in the filter properties choose the mesh quality parameter variable you want to visualize, it is equal to zero where the mesh is good, one where the grid presents that particular problem
- set the minimum and maximum threshold values as 0.5 and 1 and click on the small tick in the upper part of the filter property
- in the pipeline menu activate the visualization of the entire file “system.foam” and set “Opacity” value in its “Representation” property equal to 0.3
Completing these steps you are able to take a look at the whole file in transparency with problematic mesh zones highlighted in red.
You can try now with your own geometries and meshes. Using CONSELF is free, all you have to do is to register and signup for the WELCOME plan. If you need inspiration or a detailed tutorial, don’t forget to take a look at our dedicated page, you will be able to learn how to deal with CONSELF platform very quickly.
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CONSELF wants to make state of the art, cutting edge technology, available to every professional in the globe.
CFD & FEM simulation software is a very powerful tool, with its adoption optimization and innovation can be achieved in every field. To make this instrument accessible to everyone means lowering costs, but mainly to develop an infrastructure that favours a super-easy adoption by market new entrants.
CONSELF is highly committed and will pursue this goal working side by side with professional and industries to define the best strategies and solutions.
Alessandro Palmas – firstname.lastname@example.org