Feel free to add any relevant comments to the issue,
https://github.com/usnistgov/fipy/issues/690.
On Mon, Jan 13, 2020 at 1:36 PM Daniel Wheeler
wrote:
>
> Hi Chaitanya,
>
> I think you're correct. It seems that term should be multiplied by the
> time step. The tests all pass with your change. Would you like to
> submit a pull-request for that change?
>
> The way time stepping works is a bit weird in that equation so it
> wasn't clear to me what my intention was when I wrote that code.
> Anyway, I'll add it as an issue in FiPy.
>
> Thanks!
>
> On Thu, Jan 9, 2020 at 9:13 PM Chaitanya Joshi
> wrote:
> >
> > Hi,
> >
> > I am working with the leveler.py script in the level set examples. The
> > script chooses dt value for solving the equations based on the maximum
> > velocity of the interface at any given instant and the CFL number.
> >
> > Script: leveler.py
> > dt = cflNumber * cellSize / extOnInt.max()
> >
> > I changed that to a user specified fixed dt. To test the changes I made, I
> > ran the script for a flat interface and plotted acceleratorVar.interfaceVar
> > as a function of time for different dt values. Unfortunately, I was unable
> > to get dt convergence. By trial and error, I found out that if I call
> > AdsorbingSurfactantEquation with consumptionCoeff=None,
> > I get dt convergence. I then went through the
> > AdsorbingSurfactantEquation.py to see if I can find something. I think
> > there is a dt term missing in the AdsorbingSurfactantEquation.py.
> >
> > Script: AdsorbingSurfactantEquation.py
> > self.eq = TransientTerm(coeff = 1) -
> > ExplicitUpwindConvectionTerm(SurfactantConvectionVariable(distanceVar))
> > self.dt = Variable(0.)
> > mesh = distanceVar.mesh
> > adsorptionCoeff = self.dt * bulkVar * rateConstant #dt
> > multiplication
> >spCoeff = adsorptionCoeff * distanceVar._cellInterfaceFlag
> > scCoeff = adsorptionCoeff * distanceVar.cellInterfaceAreas /
> > mesh.cellVolumes
> > self.eq += ImplicitSourceTerm(spCoeff) - scCoeff
> > if otherVar is not None:
> > otherSpCoeff = self.dt * otherBulkVar * otherRateConstant *
> > distanceVar._cellInterfaceFlag #dt multiplication
> > otherScCoeff = -otherVar.interfaceVar * scCoeff
> > self.eq += ImplicitSourceTerm(otherSpCoeff) - otherScCoeff
> >
> > if consumptionCoeff is not None:
> > self.eq += ImplicitSourceTerm(consumptionCoeff) #This is
> > where I think a dt term is missing
> >
> > I believe the line should be
> > if consumptionCoeff is not None:
> > self.eq += ImplicitSourceTerm(consumptionCoeff*self.dt)
> >
> > Please let me know if I am thinking on the right lines.
> >
> > Regards,
> > Chaitanya
> >
> >
> >
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>
>
>
> --
> Daniel Wheeler
--
Daniel Wheeler
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