snappyHexMesh: Feature snapping of thin membrane edge
 

Dear all,

attached to this post is a small test case of a thin membrane I am trying to mesh using snappyHexMesh. while the result overall is good, I noticed the edges are very rough. first intuition was to use a feature edge so snappyHexMesh would snap elements to the exact surface, but clearly that is not working - see screenshot attached.

anybody have an idea what could be wrong here?

thanks,

guenter

Hai Guenter :),

Detected 0 feature points, could be the first point to fix, so

Could you try to use the attached emesh file? or even in your eMesh file replicate the edge list to three times.

( during the initial check, it seems the way Snappy took the points is bit different.Meaning to detect an edge (0 1), you have to put this edge for three times!!!

I hope this can help in using the feature edges properly.


Best regards,
Dominic Britto & Bernhard !

attachement
 

pls see the attachment. :)

Hai Guenter,:)

It seems for a thin surface the Edge list have to be duplicated min 1 more time.

see the attached pngs, for further comparison btn single edge list - double edge list - double edgelist with tol 10 & 0.01.

But still the snapping is not done very perfectly, probably, this surface is continuously changing in angle in 3D and probably not easy for the snappy to catch the edges in a smoother way, as the initial blocks are done in an orthogonal manner!

Some more suggestions form other users also expected!!!

Thank you,
Dominic Britto.I
:)

dominic,

very nice work! :) thanks for looking into this, definitely the idea to have the edge list twice is a big step forward. i am wondering why this is necessary - mabe thin, one-sided objects are not really supported - would be interesting to see if one creates a - still very thin - two-sided version of this shape?

thanks again and best regards,

guenter

Hi Dominic,

why does it help to double the edge list? I've got a similar problem with a pipe with a diameter of 1 cm placed under a large desk, which snappy refuses to mesh at all. Even replicating the list ten times won't help. :/

Thanks, Robert

EDIT: I still don't know WHY, but that replication-trick really did it now! Thank you so much!

Thanks for this information, it helps a lot !

meshing baffles and boundary condition
 

Hello foamers,


Excuse me for restarting this thread again. i have a similar problem. I have a very simple geometry of a box with a zero thickness surface inside. i created the geometry in salome.Exported geometry as stl files and meshing in snappyHexMesh. I used the "facetype baffles" in snappy hex mesh to create baffle.
I have the following questions:
1. After meshing it shows the master and slave boundary in polymesh/boundary files. how to set boundary conditions for theses surfaces in 0 folder?

Am I missing something. There is not tutorials for the method where snappyhexmesh is used to create baffles. I have tried the tutorials Tjunctionfan and thermal baffles tutorials but they use createbafflesDict. but I want to generate baffles for the geometry stl file i created in Salome. Could someone through some light. I m stuck at this point.

I m using OpenFoam 2.3.0

I have posted the question also in
http://www.cfd-online.com/Forums/ope...tml#post618403

#5

regards,
Naresh