error with simplefoam.
hi
i am running simpleFoam, when arriving at time =6 i get this error, can anyone please tell me what does this mean? Quote:
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change your fvSolution solver from GMAG to another some thing else ;)
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can you suggest something for me?
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for example PCG
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Hi with PCG it works till time 642, then nothing..
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your numerical solution diverges, you may want to check
1) your BCs 2) your fvSchemes 3) or using higher under relaxation Best Regards |
yesh you are right.
It was my BC i should have put negative for speed, Can you please tell me what indicated to you that the solution is diverging? thanks a lot |
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well izna
first look at your continuity :) Quote:
However there are several ways to understand whether it converges or not. for example your residual should be decreasing or if residuals became fixed, it should be less than an specific number in OpenFoam, you can save your terminal print in a log file by following command: Quote:
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also there are other easier tools to plot residual, search in forum |
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thanks a lot Nima For your patience.. In a simulation where i used PCG,with simpleFOAm, i obtain the above while iteration ...is it divergence? |
nope, it was not about convergence issue, i feel it's a bug in GAMG solver, i saw it before in some cases, so i suggested you to change your schemes
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hello Nima
thanks for the reply.. When doing a simualtion i notice that it say:" No finite volume option present" Is not that a bit abnormal? I mean normlaly we try to solve using the finite volume method...so what method is it using if not finite volume? |
nope, it returns to new OpenFOAM file Dict called fvOptions in system directory,
it seems OpenFOAM group are going to integrate some solvers options such as MRF zone or porous media, in one dict for modification. |
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HI nima.. After 1081 iterations why sudenly error? i am soo lost here..;( |
it seems some thing is wrong in solving Matrix :), i guess you need check your mesh, because PCG is almost stable solver :), maybe change your preconditioner
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hello
I am solving a 2 D case, but each time error was displayed..I am sending you my system folder can you please have a look? I am desperate here..:( :( :( https://www.dropbox.com/sh/hlwk4g3bsk1zi8p/iPm_UXOZ9k |
did you check your mesh witch checkMesh command?
your fvSolution setup is OK, but as you use an steady-state solver, you may want to use relaxation to converge easier |
hii\
Check mesh returns okay mesh.. no skewness or aything.. I tried pisoFoam, but after 292 iterations i obtain errors...:( i am honestly lost now.. please do advice...:( what pre cond you advice? Quote:
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izna look log file:
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you should monitor courant number, continuity and other variables residual! i recommend: 1- check your BC 2- off your turbulence (simulate laminar flow at first) 3- use under relaxation 4- use first order schemes |
everything is fine Nima, i checked it all.. but i think its my Boundary condition.. I am simulating in 2D my west bounday is Inlet and all threee other bounday ( ie north south and east) are Outflow.. So for this case i used
1) U folder outflow is zero gradient 2) P outflow is type fixedValue; value uniform 0; 3) k and epsilone are zero gradient 4)nut is fixed value 5) nuTilda is zero gradient do you think those values for Outflow are fine? |
it seems fine, just try for sides wall, slip BC
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hii
But i want my wind to go out from all 3 boundary hence i choose outflow for all 3.. |
then try inletOutlet
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thanks Nima..
I am going to try this for the full folder of 0.. |
hi.
with inletoutlet i achieve convergence at 313 but when i view my domain.. then complete blue colour ie zero velocity.. https://www.dropbox.com/sh/hlwk4g3bsk1zi8p/iPm_UXOZ9k |
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Hi Nima,
I'm using OF2.2.2 and am solving a laminar problem using modified buoyantBoussinesqSimpleFoam. blockMesh compiles well. But when I run it I get this error. Its the same as what Izna had. I've double checked the boundary conditions and the geometry. They seem to be fine. I do not know why this error persists Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Thanks in advance.Attachment 27064 Attachment 27065 |
Hi,
Judging by the error that has appeared I think its a problem in my fvSolutions file. Am I right? Also, since I've switched off turbulence I needn't include the discretization schemes for k, epsilon, omega and nut, right? Is that what is causing the error? Update: I just tried running another solver with the same boundary condition. and I get the exact same error. Is it a generic one? I'm not able to find out what it is from the error that I get. Any help will be really helpful, 'cos I'm lost at this point. Thanks. |
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