[cyln]

Dear OpenFOAM community,

I was using cyclic BC in OF for one of my simulations. However, next to the cyclic boundaries, I was getting an unexpected gradient in my flow parameters.


Then, I decided to do a benchmark study whose pictures are attached. I am getting the same gradient next to the cyclic boundaries in the benchmark study as well. The same situation is present for slip wall BC, however, since I need to figure out how to make cyclic BC work in OF, first I would like to know why this gradient occurs.

I generate my mesh in ICEM, and then convert it to foam mesh using fluent3DMeshToFoam. Then, I use createPatch utility to generate the cyclic boundary condition. In openfoam, I am using pimpleFoam solver.


People have been using the cyclic boundary condition in OpenFOAM for their research for a long time. Has someone ever experienced this issue? Do you know why this gradient is happening?

If nobody knows the answer, how can we trust OpenFOAM ?!?

Cheers,
Cyln

[tomf]

Hi,

It looks like you are looking at interpolated data. Do you see the gradient also when there is not interpolation? I am not sure which post-processing utility you are using, but in ParaView you can select point values or cell values. You should use the latter for these kind of checks.

Regards,
Tom

[cyln]

It is not an interpolation problem. The cyclic BC is not correctly imposed as I get unusual values when I check point values as well. The post processing tool is Tecplot.

[tomf]

Hi,

I meant you should look at cell values, not at point values. Because you also have a gradient next to your slip wall now, which makes no sense either.

Regards,
Tom