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

simpleFoam solver crashing after few iterations

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

Like Tree1Likes
  • 1 Post By nandhakumar

Reply
 
LinkBack Thread Tools Display Modes
Old   June 22, 2016, 10:41
Default simpleFoam solver crashing after few iterations
  #1
New Member
 
VIJAYA KUMAR G
Join Date: Jun 2016
Location: Chennai, India
Posts: 19
Rep Power: 4
VIJAYA KUMAR is on a distinguished road
Hi everyone

I am new to OpenFoam. I wanted to do 3D analysis of Jet Impingement on a flat plate using simpleFoam. The problem is my solver crashes after few iterations.

Please help me out !!

I am attaching my files for reference !!

i used ICEM_CFD unstructured meshing and imported in Open FOAM !!

My error message

#0 Foam::error:rintStack(Foam::Ostream&) at ??:?
#1 Foam::sigFpe::sigHandler(int) at ??:?
#2 ? in "/lib/x86_64-linux-gnu/libc.so.6"
#3 double Foam::sumProd<double>(Foam::UList<double> const&, Foam::UList<double> const&) at ??:?
#4 Foam::PCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?
#5 Foam::GAMGSolver::solveCoarsestLevel(Foam::Field<d ouble>&, Foam::Field<double> const&) const at ??:?
#6 Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMa trix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const at ??:?
#7 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?
#8 Foam::fvMatrix<double>::solveSegregated(Foam::dict ionary const&) at ??:?
#9 Foam::fvMatrix<double>::solve(Foam::dictionary const&) at ??:?
#10 Foam::fvMatrix<double>::solve() at ??:?
#11 ? at ??:?
#12 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#13 ? at ??:?
Floating point exception (core dumped)
VIJAYA KUMAR is offline   Reply With Quote

Old   June 22, 2016, 19:40
Default
  #2
Senior Member
 
Michael Prinkey
Join Date: Mar 2009
Location: Pittsburgh PA
Posts: 363
Rep Power: 18
mprinkey will become famous soon enough
It has been a while since I worked with openfoam, but that seems to be erroring out in the Preconditioned CG solver that is called to solve the coarsest AMG grid and that system is singular or otherwise produced a floating point exception...divide by zero, probably.

Does your domain have an outlet? This looks like the continuity equation (aka pressure (correction) equation) is singular likely because you have inconsistent boundary conditions set. If you have, say, an inlet for the jet and no outlets, your boundary conditions violate the global mass conservation condition. This violation can manifest in a pressure (correction) system that cannot be solved--because no pressure field will make the mass fluxes locally conservative if the overall system is non-conservative due to boundary conditions.
mprinkey is offline   Reply With Quote

Old   June 23, 2016, 05:21
Default
  #3
New Member
 
VIJAYA KUMAR G
Join Date: Jun 2016
Location: Chennai, India
Posts: 19
Rep Power: 4
VIJAYA KUMAR is on a distinguished road
There is an outlet that I have named it as pressureoutletwall.
Is this a problem

herewith I am attaching my case.

log file is attached here
Attached Files
File Type: c log.C (6.4 KB, 15 views)
VIJAYA KUMAR is offline   Reply With Quote

Old   September 23, 2017, 14:38
Default
  #4
New Member
 
rajaram
Join Date: Jun 2017
Posts: 4
Rep Power: 3
vijy is on a distinguished road
Hey vijay kumar ,My name is Vijay singh...I am also solving same problem as you....
and same error is occuring to me also...if you found any solution of the problem...please help me....
vijy is offline   Reply With Quote

Old   September 26, 2017, 03:11
Default
  #5
New Member
 
CFDfreak
Join Date: Dec 2016
Posts: 15
Rep Power: 3
nandhakumar is on a distinguished road
can you explain your case setup briefly. It seems your your epsilon values are blowing up. How did you calculate your k and epsilon values for your model. The schemes used. try running in lower order schemes with low relaxation factors.
nandhakumar is offline   Reply With Quote

Old   September 26, 2017, 07:17
Default
  #6
New Member
 
rajaram
Join Date: Jun 2017
Posts: 4
Rep Power: 3
vijy is on a distinguished road
Thanks for the reply...@nandhakumar
I have attatched all the requied files includinlog files...I am using simpleFoam solver...
Renolds number is 35000..
formulas used are...
ε =(Cμ)^ 0.75*( k)^ 1.5/l
l=0.20D, where D=diameter of nozzle(40mm)
k = (U x ′ 2 + U y ′ 2 + U z ′ 2 )/2

I am eagerly waiting for your reply...
Attached Files
File Type: gz all files.tar.gz (2.9 KB, 2 views)
vijy is offline   Reply With Quote

Old   September 26, 2017, 08:34
Default
  #7
New Member
 
CFDfreak
Join Date: Dec 2016
Posts: 15
Rep Power: 3
nandhakumar is on a distinguished road
Hello

I have read your boundary condition files.certain things are bit confusing. swirl flow rate inlet velocity i never used so i cannot comment on that.

Everything looks fine try reducing the tolerance value to 10e-5 or 10e-4 in fvSolution file and try changing the under relaxation values. If that doesnt work try calculating k and epsilon value from other formulas.
Teosim likes this.
nandhakumar is offline   Reply With Quote

Old   September 27, 2017, 06:14
Default
  #8
New Member
 
Join Date: Aug 2017
Location: Milan Area, Italy
Posts: 10
Rep Power: 2
Teosim is on a distinguished road
Hi viji,
I am not confident with your case setup and OF version you are using but here are some thoughts.

How about the quality of your mesh? Could you please upload checkMesh log?

Noticed the simulation starts at time step 40: is that a "clean start" or is the solver resuming a previous simulation?

On the pressure BC: is fixedValue=0 exactly what you wanted for patch named "wall1" and "wall2"?

On the U BC: I never used swirlFlowRateInlet Velocity but is the velocity inlet vector (13 0 0) correctly oriented? (it might be just me but sometimes i overlook that)

You could try to increase relative tolerance for solvers (i.e. 0.01 for p and 0.001 or less for U etc.). You could also add a minIter entry (setting minimum number of iteration to 3 or 5)

Finally you could try starting the solver with turbulence switched off and turn it on after it stabilizes a little.
Teosim is offline   Reply With Quote

Old   September 28, 2017, 13:52
Default tolerance value in fvSolution
  #9
Member
 
Jon Elvar Wallevik
Join Date: Nov 2010
Location: Reykjavik, ICELAND
Posts: 91
Rep Power: 13
JonW will become famous soon enough
hi folks
if you are working with difficult mesh combined with difficult material model, you should not be shy in reducing the tolerance value.
In some cases, I am using tolerance between 0.1e-9 and 0.1e-11.
This is actually when I am using interFoam, with difficult grid and difficult material model. But the point is, when I started, I was very shy in reducing these tol values, and the solver always crashed. Now I am not, and everything is working perfectly.

If you are afraid that the solver is calculating something incorrect after a full run, make a case in which there exists an analytical solution for comparison.

If you are doing time dependent calculation, be careful on these relaxation factors. These can actually make your simulation results incorrect. Relaxation is actually best for time independent problems. Can be used for time-dependent problems as well, but just be careful (for example, run several runs with different relaxation factors to see if there are any difference).

cheers
J.
JonW is offline   Reply With Quote

Old   October 5, 2017, 17:01
Default
  #10
New Member
 
Ashish Magar
Join Date: Jul 2016
Location: Mumbai, India
Posts: 25
Rep Power: 3
ashishmagar600 is on a distinguished road
Hii

Please refer this post, you may find some direction to correct your case:
Time-step continuity error with diverging p and U

I had similar issues. Common mistakes are bad meshing and incorrect flow physics. If all is sure then there is a possibility of a crash in the mesh.

Regards,
Ashish
ashishmagar600 is offline   Reply With Quote

Reply

Tags
openfoam, simple foam

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
Cannot run the code properly: very large time step continuity error crst15 OpenFOAM Running, Solving & CFD 9 December 14, 2014 19:17
calculation stops after few time steps sivakumar OpenFOAM Running, Solving & CFD 7 March 17, 2013 07:37
SLTS+rhoPisoFoam: what is rDeltaT??? nileshjrane OpenFOAM Running, Solving & CFD 4 February 25, 2013 05:13
Error while running rhoPisoFoam.. nileshjrane OpenFOAM Running, Solving & CFD 8 August 26, 2010 12:50
Unknown error sivakumar OpenFOAM Pre-Processing 9 September 9, 2008 12:53


All times are GMT -4. The time now is 12:11.