## ListGetInteger error in Periodic BC

Numerical methods and mathematical models of Elmer

### Re: ListGetInteger error in Periodic BC

Hi Peter,

Indeed there is a problem with my mesh and with the piece of code I wrote to make it.
The z values of the inlet/outlet nodes don't correspond. I am trying to figure this out.

This bring a different question.
Since this is in cylindrical coordinates, is it better computationally to solve the whole thing in r, theta, z coord? Then it is a simpler translation between the inlet and outlet and my mesh will be simpler to build and be more accurate.

Denis
denis.cohen

Posts: 25
Joined: 15 Dec 2010, 13:50

### Re: ListGetInteger error in Periodic BC

Hi Denis

There is no choice of 3D problems other than cartesian. You can have effectively cylindrically symmetric case using FlowSolver with also a third component for the velocity. However, even this should live in a 2D (r,z) mesh.

There is a issue to remember for periodic problems and vector fields: the periodicity is only obtained when the vectors are rotated to the same reference. Therefore for vector valued problems and rotational BCs, the periodic system should be applied together with normal-tangential system for the vector field.

-Peter
raback

Posts: 1903
Joined: 22 Aug 2009, 11:57
Location: Espoo, Finland

### Re: ListGetInteger error in Periodic BC

Thanks for the info.
Will try to fix all that.

Denis
denis.cohen

Posts: 25
Joined: 15 Dec 2010, 13:50

### Re: ListGetInteger error in Periodic BC

Hi Peter,

I've corrected the mesh which I think is now OK.
However I am still getting the WARNING in the periodic BC. The points between inlet and outlet should be close enough after a rotation of -pi/6. May be I am writing my Periodic BC in my sif file incorrectly.

Attached is the sif, the mesh and a figure of the mesh.

Denis
Attachments
mesh figure
mesh.png (47.26 KiB) Viewed 125 times
mesh3d_fit.tar.gz
mesh data
elmer_test001.sif
sif file