Learning Forum

[Soumit Sarkar]

Fluent 2022 R2 will create a "bridge of cells" between 2 seperate bodies in the fluid flow domain in between gaps of 25-30mm or less. Originally our CFD was done in Ansys 19 until our university discontinued support for it, and we switched to Ansys 22. We have never had a problem meshing bodies with such small gaps, and the scoped sizing is able to create cells of 0.5mm at minimum. Each seperate object has a unique identifier, and are not combined in the geometry. In this example, the ground of the domain and the undertray of the vehicle have "combined" in 2 spots. This is less than ideal as the ground moves relative to the stationary vehicle to represent the ground effect of the fluid flow. Is there a setting or option that can be changed to account for tighter tolerances during meshing, that is outside the scoped sizing and minimum element sizing settings?

[Rob]

Is there an option to ignore self intersection? I suspect the faces are close enough that the cells bridge the gap and therefore leak. The tools were upgraded so there may have been a default change, or an additional option was added. 

[Soumit Sarkar]

 

I have not found an option or a setting that ignores self intersections before the CAD obejcts are wrapped in the meshing process. Is there a way to change this or set a minimum tolerance between each object to prevent self intersections from forming?

 

[Rob]

Assuming you're using the workflow, 

 

Otherwise, there are recovery options in the Wrap tool. 

[Soumit Sarkar]

I use a jou script to automate the meshing process in a HPC cluster. The objects/wrap commands do not include an option to set a minimum gap between objects or an option to ignore parallel faces. I have found boundary/remesh/controls/intersect/ignore-parallel-faces, but this command requires me to remesh and restitch faces which makes the original wrapping process moot.

[Rob]

I think the wrapper does have a tolerance setting, the problem with journals etc is that they don't always work well in different versions as additional options are added. I'm fairly sure there are tools for intersection and overlap in the repair tools.