Topology-Changing with movingConeTopo
 

Hello Open-Foam-Users,

I am trying to simulate a moving box in a box with cell layer addition/removing.
Therefore i began with the movingComeTopo-tutorial, which uses the movingConeTopoFvMesh for mesh-movement and manipulation.
The tutorial runs, but when im trying to replace the tutorial-mesh (and the boundaries, of course) with my Salome-made unv-mesh (ideasUnvtoFoam) i get that error:


I looked into the source files and 'et voila': That error occus when a variable 'topoChanger_.size()' is set to 0. The variable 'topochanger' is constructed in topoChangerFvMesh.C with 'topoChanger_(*this)'.

This leeds to the following questions:
What is that variable for? (my C++ knowledge = bad)
Why is its size zero for my Mesh? Is there maybe anything wrong with the ideasUnvToFoam-tool, although the generated files for points, faces,.. look exactly like the one made with blockMesh.

Maybe some of you know whats going wrong.

Thank you all for reading this!

Michael

hi michael,

please delete all *Zones in $FOAM_CASE/constant/polymesh and then run the app again.

Christof

Hi christoph,

thank you very much for your advice!

There was a faceZones-file I deleted now, but another error follows:

4.5 and 15.5 are the defined obstale edges and according to the tutorial the beginning of the moving box. Maybe there is something wrong with my leftEdge-definition: I assumed that the leftEdge parameter defines the beginning of the mesh, so its set to 0.

PS: this error produces the empty faceZones-file, which leads to error I posted above.

Michael

The error is clear....your zones are both zero. So the lib cant add layer-meshmodifier. I think there is somethink wrong with your case setup. Maybe the min/max thickness values? It is possible to upload your case?

Christof (note the "f" at the end ;) )

Hi Christof (sorry about the ph ;)),

here is the upload (32mb, with mesh): http://rapidshare.com/files/28613086...sh.tar.gz.html

Note that this mesh was originally written for movement in y-direction. I read that movingConeTopo is written for movement in x-direction, so I changed my movement to x-direction, although the movement itself makes no sense for now. If I see the first cell layer being deteted and another being added, I will transform the mesh immediately. ;)

Edit: The Mesh is hex with 0.25 cell-size everywhere in every dimension (easy setup for the first). Thickness is for left and right defined as 0.125=min and 0.75=max.

Hi Michael,

i looked through your case and to the code of movingConeTopoFvMesh. The faceZones are 0 because the if condition is false. (Have a look at line 125 of movingConeTopoFvMesh.C) This lib is exlusive for similar cases like the tutorial case.
I think you have to modify the lib.

Have a nice day,
Christof

Hi christof,

your hint was absolutely correct! Many, many thanks! ;)
Defining that obstacle edges in the dynamicMeshDict and(!) in the code doesnt make sense to me, but however: the calculation starts now :)

But there must be other tutorial-specific variables in the code, because the calculation aborts when topology-change is done (the solver claims zero-volume-elements in layerAdditionRemoval.C line 208). That does not surprise me, because the solver ignores the specified minThickness and maxThickness values and compresses the cells until they reach zero-volume. Maybe the (really small) thickness values of the tutorial are still somewhere implemented.

Hi,

the solver looks into the dictionary for min and max thickness. Maybe your setup is bad. Play a bit with these values and have fun.

Nice day,
Christof.

Doing something similar, here are my changes to movingConeTopoFvMesh.H:
(That is, I _think_ the main changes I need here are relevant to where the solver chooses the initial faces-to-extrude.)

My difficulty is in trying to get OpenFOAM to recognize this new puffValveTopoFvMesh as a valid dynamicFvMesh type. I'm not sure if this means that it's an "application" or a "library". I tried to adapt the dynamicMesh/topoChangerFvMesh/Make entries as follows:

files:
options:
I don't think I've got the Make/files and Make/options entries set up right because the compilation (with wmake) yields the following:
followed by lots more errors in a similar vein.

Any ideas? Thanks.

Sarah,

Make your own class that derives from topoChangerFvMesh (take a cue from any of the other solvers, like mixerFvMesh, for example), put it in its own sub-directory (like puffValveTopoFvMesh/puffValveTopoFvMesh.C), and add an entry to Make/files in the topoChangerFvMesh folder.

Also, use 'wmake libso' to make a library (as opposed to 'wmake', which makes an application instead)

You would also want to change the TypeName entry in your header file as well, since that entry is used for run-time selection

Okay, I think I got that sorted out. Here's the resulting puffValveTopoFvMesh.C, for those taking notes at home:
I've also made the recommended edits / additional files as deepsterblue's outlined.

I get a dimensions error when I run my modified sonicDyMFoam, but I think that's quasi-separate from the topoChangerFvMesh business, so I'll talk about it in the other thread.