CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM

Trouble with Mesh non-orthogonality

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   October 2, 2012, 15:48
Default Trouble with Mesh non-orthogonality
  #1
Member
 
M Mallikarjuna Reddy
Join Date: Jul 2012
Posts: 91
Rep Power: 5
mmkr825 is on a distinguished road
Hi Foamers,
I prepared my solver which is non-linear PDE. I am working on suspension flow (Fluid+Particles) through different geometries. When i compiled my solver then it is giving no errors, but when i run my case file by using my solver it is giving some error message.

Error message:-
Starting time loop

Time = 1nl [0 0 -1 0 0 0 0] 0.02716
DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 4.70429e-06, No Iterations 5
DILUPBiCG: Solving for Uy, Initial residual = 0, Final residual = 0, No Iterations 0
swak4Foam: Allocating new repository for sampledGlobalVariables
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam211/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam211/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam:ILUPreconditioner::calcReciprocalD(Foam::Fi eld<double>&, Foam::lduMatrix const&) in "/opt/openfoam211/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#4 Foam:ILUPreconditioner:ILUPreconditioner(Foam: :lduMatrix::solver const&, Foam::dictionary const&) in "/opt/openfoam211/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#5 Foam::lduMatrix:reconditioner::addasymMatrixCons tructorToTable<Foam:ILUPreconditioner>::New(Foam ::lduMatrix::solver const&, Foam::dictionary const&) in "/opt/openfoam211/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#6 Foam::lduMatrix:reconditioner::New(Foam::lduMatr ix::solver const&, Foam::dictionary const&) in "/opt/openfoam211/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#7 Foam::PBiCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam211/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#8 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/openfoam211/platforms/linuxGccDPOpt/lib/libfiniteVolume.so"
#9 Foam::fvMatrix<double>::solve() in "/home/malli_reddy/OpenFOAM/malli_reddy-2.1.1/platforms/linuxGccDPOpt/bin/twoFoam"
#10
in "/home/malli_reddy/OpenFOAM/malli_reddy-2.1.1/platforms/linuxGccDPOpt/bin/twoFoam"
#11 __libc_start_main in "/lib/i386-linux-gnu/libc.so.6"
#12
in "/home/malli_reddy/OpenFOAM/malli_reddy-2.1.1/platforms/linuxGccDPOpt/bin/twoFoam"
Floating point exception


My governing equation involves non-linear equations. When i give good initial guess (i.e by running the case by using linear solver instead of non-linear solver at first for the guess) then the case is running properly and giving good results for simple channel flow.(in which for Mesh non-orthogonality Max: 0 average: 0)
When i repeat the above same procedure for non zero Mesh non-orthogonality then after two iterations the solution is diverging.

Please let me know what is the problem and what above error trying to explain.

Thanks
Regards
Mallikarjuna
mmkr825 is offline   Reply With Quote

Old   October 25, 2012, 01:13
Default
  #2
Member
 
Join Date: May 2012
Posts: 68
Rep Power: 5
som87 is on a distinguished road
Only Ux and Uy?..You need to consider a Control Volume for OF.It appears there is some problem with the geometry specification.If you are going for solely 2D case, create a unit mesh in the z direction...

hope it helps
__________________
Best wishes,

Somdeb Bandopadhyay
som87 is offline   Reply With Quote

Old   October 25, 2012, 12:09
Default
  #3
Senior Member
 
kmooney's Avatar
 
Kyle Mooney
Join Date: Jul 2009
Location: Amherst, MA USA - San Diego, CA USA
Posts: 285
Rep Power: 9
kmooney is on a distinguished road
Quote:
Originally Posted by som87 View Post
Only Ux and Uy?..You need to consider a Control Volume for OF.It appears there is some problem with the geometry specification.If you are going for solely 2D case, create a unit mesh in the z direction...

hope it helps

If you're running a 2D case OF will only solve for the x and y components in the segregated solution so there's no problem there. If introducing mesh non-orthogonality is killing your stability, try increasing the number of nNonOrthogonalCorrectors in the /system/fvSolution dictionary. If you mesh is too skewed, however, you might be out of luck and want to try some different meshing strategies.
kmooney is offline   Reply With Quote

Old   October 25, 2012, 18:00
Default
  #4
Member
 
Join Date: May 2012
Posts: 68
Rep Power: 5
som87 is on a distinguished road
O my......totally forgot about segregated solver situation. Thank you very much for the correction.
__________________
Best wishes,

Somdeb Bandopadhyay
som87 is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
No layers in a small gap bobburnquist OpenFOAM Native Meshers: snappyHexMesh and Others 6 August 26, 2015 09:38
Layers:problem with curvature giulio.topazio OpenFOAM Native Meshers: snappyHexMesh and Others 10 August 22, 2012 09:03
2D Mesh Generation Tutorial for GMSH aeroslacker Open Source Meshers: Gmsh, Netgen, CGNS, ... 12 January 19, 2012 04:52
basic of mesh refinement arya CFX 4 June 19, 2007 12:21
Mesh Mignard FLUENT 2 March 22, 2000 06:12


All times are GMT -4. The time now is 09:07.