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meshing problems , Kind Sir please Help!

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Old   April 27, 2011, 22:29
Default meshing problems , Kind Sir please Help!
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Stephen
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Hi all

I wonder if some kind soul can help. I am running a simple case, a pipe with 3 outlets. I would like to optimise the outlets. to find the best diameter for them.

I Drew the pipe and exported it as a STEP file, Imported that into Netgen and Meshed it. Exported the file as a Netgen Neutral file into Descretizer where I set up the patches . Inlets and outlets, walls etc

However somewhere along the line; patch0;type;patch;nFaces;0;startFace;37441 didnt get any faces

Sooo I deleted it ( well its worth a try especially if you dont know what you are doing !!)

well openFoam ran up to time 69 when it crashed, with this warning;

Time = 69

smoothSolver: Solving for Ux, Initial residual = 0.492886, Final residual = 0.0034533, No Iterations 2
smoothSolver: Solving for Uy, Initial residual = 0.830014, Final residual = 0.0074513, No Iterations 3
smoothSolver: Solving for Uz, Initial residual = 0.456928, Final residual = 0.00419737, No Iterations 5
GAMG: Solving for p, Initial residual = 0.00120776, Final residual = 3.01571e-06, No Iterations 2
time step continuity errors : sum local = 8.39734e+18, global = -4.7615e+11, cumulative = -4.7615e+11
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam170/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/opt/openfoam170/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 in "/lib/libc.so.6"
#3 Foam::LimitedScheme<double, Foam::limitedLinearLimiter<Foam::NVDTVD>, Foam::limitFuncs::magSqr>::limiter(Foam::Geometric Field<double, Foam::fvPatchField, Foam::volMesh> const&) const in "/opt/openfoam170/lib/linux64GccDPOpt/libfiniteVolume.so"..............blah blah

So I ran CheckMesh

and got this; Snip...Checking topology...
****Problem with boundary patch 0 named patch1 of type wall. The patch should start on face no 37441 and the patch specifies 37965.
Possibly consecutive patches have this same problem. Suppressing future warnings.
***Boundary definition is in error.
Point usage OK.
Upper triangular ordering OK.
Face vertices OK.
Number of regions: 1 (OK)....

snip ,,,, Mesh non-orthogonality Max: 65.4224 average: 21.0547
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 0.737253 OK.

Mesh OK.


So it seems to me that the patch0 is the problem and as I guessed just deleting it wasn't such a good idea!

So ( If this is the problem ) do I correct this problem and give patch0 faces or remove it ?


Secondly I would like to find a robust work path so that I can reduce this learning curve ( and example , the meshing options in Netgen I just dont understand and I cannot find the answer anywhere)


Sorry about the length of this post but I tried to include as much information as possible

kind regards

Stephen
Can post the entire warning message if needed
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Old   April 29, 2011, 01:57
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Bump

anybody???

Stephen
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Old   April 29, 2011, 15:35
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I recently had to export a geometry from Solidworks into openfoam and I found out that the safest way was to export the geometry as a step file, import it into an open source meshing software called salome, mesh it there however you want and export as a .unv file which can then be converted into openfoam using ideasUnvToFoam converter.

I remember I had a similar problem where the face number wouldn't match on particular patches and that would cause the solver to crash. I suggest you might wanna try out salome because it's very easy to use and gives you a lot of versatility on how to set up patches that will be boundaries in openfoam, especially the 'explode' option, so useful!

I also remember deleting the certain patches to make things work but it turns out that number of faces from one patch to the other must match exactly in the boundaries file and if you have even a remotely complicated geometry, doing that by hand becomes very tedious.

So give salome a shot. Hope this helps =)
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Old   April 30, 2011, 08:11
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Quote:
Originally Posted by atareen64 View Post
I recently had to export a geometry from Solidworks into openfoam and I found out that the safest way was to export the geometry as a step file, import it into an open source meshing software called salome, mesh it there however you want and export as a .unv file which can then be converted into openfoam using ideasUnvToFoam converter.

I remember I had a similar problem where the face number wouldn't match on particular patches and that would cause the solver to crash. I suggest you might wanna try out salome because it's very easy to use and gives you a lot of versatility on how to set up patches that will be boundaries in openfoam, especially the 'explode' option, so useful!

I also remember deleting the certain patches to make things work but it turns out that number of faces from one patch to the other must match exactly in the boundaries file and if you have even a remotely complicated geometry, doing that by hand becomes very tedious.

So give salome a shot. Hope this helps =)
Will give that a try on Monday morning , Strangely I know Salome is good but I hardly use it ..I will do from now !

Thanks , will post back

Stephen
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Old   April 20, 2012, 10:17
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Hi Stephen,

could you solve your problem with this:

Quote:
Problem with boundary patch 0 named patch1 of type wall. The patch should start on face no 37441 and the patch specifies 37965.
Possibly consecutive patches have this same problem. Suppressing future warnings.
Thanks,
Attila
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