[Maff]

Hi all,

I'm having some problems with cyclicAMI patches (OpenFOAM 2.1.1).
I'm working on a 3-bladed wind turbine, meshing a third of the domain (120-degree slice, single rotating reference frame).

The model is SpalartAllmaras and the solver is MRFSimpleFoam (by the way, MRFSimpleFoam is far more stable than SRFSimpleFoam in my opinion).

At the beginning I had problems with the convergence of nut and nuTilda.
After trying a lot of different schemes and relaxation factors, I noticed that "y" (wall distance in yPlusRAS) was calculated wrong. And I thought: that's why nut is not good.
With "cyclic" patches the wall distance is ok, so cyclicAMI seemed to be the problem.

Then I found this thread,
I added the cyclicAMI patches to "nonRotatingPatches" in MRFZones dictionary and now my results are ok (at least they seem ok).
But the wall distance y is still not good. I don't know if this can cause any problem, maybe with the calculation of y+.

The attached images show the problem with the calculation of y on the cyclicAMI patches (purple arrow).
The contour of y shows where the problem starts (yellow arrow), i.e. where it thinks there's a wall but there isn't.

I created the cyclicAMI patches with the following createPatchDict.

pointSync false;
patches
(
    {
        // Name of new patch
        name cyclic_half0;
        // Type of new patch
        patchInfo
        {
            type cyclicAMI;
   neighbourPatch cyclic_half1;
   transform rotational;
   rotationAxis (0 1 0);
   rotationCentre (0 0 0);
   matchTolerance 0.0001;
        }
        // How to construct: either from 'patches' or 'set'
        constructFrom patches;
        // If constructFrom = patches : names of patches. Wildcards allowed.
        patches (periodic1);
        // If constructFrom = set : name of faceSet
        set f0;
    }
 
    {
        // Name of new patch
        name cyclic_half1;
        // Type of new patch
        patchInfo
        {
            type cyclicAMI;
   neighbourPatch cyclic_half0;
   transform rotational;
   rotationAxis (0 1 0);
   rotationCentre (0 0 0);
   matchTolerance 0.0001;
        }
        // How to construct: either from 'patches' or 'set'
        constructFrom patches;
        // If constructFrom = patches : names of patches. Wildcards allowed.
        patches (periodic2);
        // If constructFrom = set : name of faceSet
        set f0;
    }
);

I tried to specify the "rotationAngle", but it doesn't seem to have any effect.

Is this a bug or am I doing something wrong? Do I have to worry about this? (will y+ be calculated right?)

Thank you in advance

[Maff]

there's an easy way to reproduce this.
in the "mixer" tutorial (incompressible/SRFSimpleFoam/mixer) replace the cyclic patches with cyclicAMI patches.
run yPlusRAS and you will get strange "y" contours.