KR102: How can I locate and fix left handed cells?

1. The left-handed faces mostly occur at locations where the surfaces that are non-conformally connected have sharp corners or contortions. When you get the left-handed faces, you can fix it in Fluent by the TUI commands


2. If the TUI option fails to repair the left-handed faces, you may try the following,

At command prompt, type (rpgetvar 'nonconformal/cell-faces) to check the current value of the variable.

Then type (rpsetvar 'nonconformal/cell-faces 2) . This sets the left handed faces.

3. You can also try the following command:

/define/grid-interfaces> use-virtual-polygon-approach

This should be used before initialization. If you are not able to find this command, this means that Fluent has already applied this algorithm while reading the mesh.

4. When you fix the left handed faces using any of the above methods, you may get cells with negative volume. You will need to repair these cells manually. It`s best to fix the problematic geometry at the grid generation stage. To identify the problematic geometry, read the case file again and create an adaption register using the IsoValue Adaption panel with the category Grid and the subcategory Face-Handedness as follows:

(a) Go to Adapt-->Iso-values

(b) Select Grid in the Iso-value of drop down menu

(c) Select Face handedness from the drop down menu below that

(d) Enter 1 for Max as well as Min value in the Iso-min and Iso-max input box

(e) Press mark

(f) Go to manage in the same panel

(g) Click on the display button to see where the negative volumes are forming

This may give you an idea of the location of problematic geometry which you may then fix in the grid generation software.

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