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[snappyHexMesh] How to eliminate skew faces in motorbike tutorial

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Old   August 13, 2014, 21:53
Default How to eliminate skew faces in motorbike tutorial
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Nick
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Hello all,

FTP so please be gentle

I have recently installed blueCFD singlecore 2.1 mingw 64 dual precision, not sure if that makes any difference or not.

So I figured out how to run the motorbike tutorial, but it exits pretty quickly during potentialFoam
Code:
/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.1                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
/*   Windows 32 and 64 bit porting by blueCAPE: http://www.bluecape.com.pt   *\
|  Based on Windows porting (2.0.x v4) by Symscape: http://www.symscape.com   |
\*---------------------------------------------------------------------------*/
Build  : 2.1-88b2f2ae3a0b
Exec   : potentialFoam -noFunctionObjects -writep
Date   : Aug 14 2014
Time   : 11:35:41
Host   : "BEBE"
PID    : 2712
Case   : C:/blueCFD-SingleCore-2.1/ofuser-2.1/run/tutorials/incompressible/simpleFoam/motorBike
nProcs : 1
SigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster
allowSystemOperations : Disallowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0

Reading field p

Reading field U


Calculating potential flow
GAMG:  Solving for p, Initial residual = 1, Final residual = 0.0401607, No Iterations 5
GAMG:  Solving for p, Initial residual = 0.0444346, Final residual = 0.0016506, No Iterations 1
GAMG:  Solving for p, Initial residual = 0.00204825, Final residual = 0.000139724, No Iterations 3
GAMG:  Solving for p, Initial residual = 0.00133821, Final residual = 0.000100228, No Iterations 1
GAMG:  Solving for p, Initial residual = 0.000143176, Final residual = 1.11963e-005, No Iterations 3
GAMG:  Solving for p, Initial residual = 6.13086e-005, Final residual = 3.67266e-006, No Iterations 2
GAMG:  Solving for p, Initial residual = 9.62095e-006, Final residual = 6.07685e-007, No Iterations 3
GAMG:  Solving for p, Initial residual = 2.883e-006, Final residual = 2.01597e-007, No Iterations 2
GAMG:  Solving for p, Initial residual = 4.68639e-007, Final residual = 6.01575e-008, No Iterations 2
GAMG:  Solving for p, Initial residual = 1.38111e-007, Final residual = 3.33552e-008, No Iterations 1
GAMG:  Solving for p, Initial residual = 4.09721e-008, Final residual = 4.09721e-008, No Iterations 0
continuity error = 2.4018e-006
Interpolated U error = 0.000275128
ExecutionTime = 22.047 s  ClockTime = 22 s

End



So I have tried to break the process down, which basically goes like this.
- I run blockMesh
- I run checkMesh, and there are no problems.
- I edit snappyHexMeshDict to split the process into individual steps
Code:
// Which of the steps to run
castellatedMesh true;
snap            false;
addLayers       false;
- I run snappyHexMesh
- I run checkMesh, there are no problems.
- I edit snappyHexMeshDict to split the process into individual steps
Code:
// Which of the steps to run
castellatedMesh false;
snap            true;
addLayers       false;
- I run snappyHexMesh
- I run checkMesh, there are skew faces.
Code:
***Max skewness = 9.5136, 18 highly skew faces detected which may impair the quality of the results
  <<Writing 18 skew faces to set skewFaces
I have tried changing this and that, but can't get rid of this error. At best I have got it down to 5 skew faces by changing the nSmoothPatch value from 3 to 2 or 4, can't recall exactly which it was.

I was hoping, that the motorbike tutorial would be well know enough that someone could point me in the right direction to resolving the problems, and completing the tutorial. FWIW I have the tutorial code, is there a set of tutorial instructions that I am missing?

Thanx in advance (fingers crossed)

Nick
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Old   August 14, 2014, 01:17
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Ah, OK.

I have managed to keep tinkering, and running the mesh very coarse I can get it to no skew errors, however I still get basically the same output from potentialFoam. Is that all that is to be expected?
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Old   July 17, 2015, 11:54
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gned
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dear Nick !
could you attach your final snappyHexMeshDict without mesh errors (checkMesh OK) and explain better which problems do you still have exactly?
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