Hi Franck,
I got this error before. This could result from your equation itself or the
discretization. You can try smaller time step and smaller grid size (dx) to
see if you can get rid of it. It seems the error stays very large when the
equation is being solved and the solver could not get to the error you
defined after the maximum iterations. That may be why you got those errors.
Maybe the developers will have more professional opinions.
Hope this helps.
Regards,
Zhiwen
On Sun, Aug 24, 2008 at 10:24 AM, franck kalala <[EMAIL PROTECTED]
> wrote:
> Thanks again for your help,
> but I still have one error message that I cannot understand, this my code
>
> **************************************************************************************************
> rom __future__ import division
> L=1.
> nx=400
> dx=L/nx
> timeStepDuration=0.012
> from fipy.meshes.grid1D import Grid1D
> mesh=Grid1D(dx=dx, nx=nx)
> from fipy.variables.cellVariable import CellVariable
> phi=CellVariable(name="saturation", mesh=mesh)
> p=CellVariable(name="pressure",mesh=mesh)
> x=mesh.getCellCenters()[...,0]
> phi.setValue(.9, where=x<.5)
> phi.setValue(.3, where=x>=.5)
> p.setValue(1.)
> pcs=0
> qin=40*((x>=.1)&(x<=.3))+20*((x>=.7)&(x<=.9))
> qout=60*((x>=.4)&(x<=.6))
> sin=.8
> pin=0
> q1s=sin*qin+phi*qout
> q2s=(1-sin)*qin+(1-phi)*qout
> if __name__=='__main__':
> import fipy.viewers
> phiviewer=fipy.viewers.make(vars=(phi), limits={'ymin':.2, 'ymax':1.1})
> pviewer=fipy.viewers.make(vars=(p), limits={'ymin':.2, 'ymax':1.1})
> phiviewer.plot()
> pviewer.plot()
> raw_input("initial condition. press <return> to proceed...")
> from fipy.terms.transientTerm import TransientTerm
> from fipy.terms.powerLawConvectionTerm import PowerLawConvectionTerm
> from fipy.terms.explicitSourceTerm import _ExplicitSourceTerm
> from fipy.terms.implicitDiffusionTerm import ImplicitDiffusionTerm
> eq1=ImplicitDiffusionTerm(coeff=1)==_ExplicitSourceTerm(q1s+q2s)
>
> eq2=TransientTerm(coeff=2)==_ExplicitSourceTerm(q1s-q2s)+PowerLawConvectionTerm(coeff=2*p.getFaceGrad())-p.getFaceGrad().getDivergence()
> steps=100
> for i in range(steps):
> eq1.solve(p, dt=timeStepDuration)
> eq2.solve(phi, dt=timeStepDuration)
> if __name__ =='__main__':
> phiviewer.plot()
> pviewer.plot()
>
> *************************************************************************************************************************
> when running this code i got the following error message
> Warning (from warnings module):
> File "C:/Python25/tsetdipha.py", line 43
> eq1.solve(p, dt=timeStepDuration)
> MaximumIterationWarning: Iterations: 1001. Relative error: 2.96727e+018
>
> Warning (from warnings module):
> File "C:/Python25/tsetdipha.py", line 43
> eq1.solve(p, dt=timeStepDuration)
> StagnatedSolverWarning: The solver stagnated. Iterations: 20. Relative
> error: 2.23961e+016
>
> Warning (from warnings module):
> File "C:/Python25/tsetdipha.py", line 43
> eq1.solve(p, dt=timeStepDuration)
> StagnatedSolverWarning: The solver stagnated. Iterations: 4. Relative
> error: 4.16036e+016
>
> Warning (from warnings module):
> File "C:/Python25/tsetdipha.py", line 43
> eq1.solve(p, dt=timeStepDuration)
> StagnatedSolverWarning: The solver stagnated. Iterations: 2. Relative
> error: 6.11332e+016
>
> This message seems to appear infinitly
>
> I don't understand this error,
> could any one to help me?
>
> Regards
>
>
>
> 2008/8/20 Jonathan Guyer <[EMAIL PROTECTED]>
>
>>
>>
>> On Aug 20, 2008, at 2:57 PM, franck kalala wrote:
>>
>> Did you not forgot a term in the second equation?
>>> eqp=ImplicitDiffusionTerm(coeff=1)==_ExplicitSourceTerm(q1s+q2s)
>>> eqphi=TransientTerm(coeff=2)==_ExplicitSourceTerm(q1s-q2s)
>>>
>>> after subtracting the two equations of the problem I sent in the attached
>>> file, there a term which looks like 2\nabla(phi\nabla p), then how to
>>> represent it?
>>>
>>
>> In an equation for phi?
>>
>> PowerLawConvectionTerm(coeff=2 * p.getFaceGrad())
>>
>> You've also got a p.getFaceGrad().getDivergence() term that isn't in your
>> .pdf and the sign of your ImlicitDiffusionTerm is wrong in eqp.
>>
>>
>>
>
>
> --
> ***********************************************
> ***********************************************
> Franck Kalala Mutombo
> [EMAIL PROTECTED]
> African Institut for Mathematical Sciences, Muizenberg Cape Town, South
> Africa
> [EMAIL PROTECTED]
> ************************************************
> ************************************************
>
