Re: Front-fixing method for moving boundary problem

On Sep 22, 2008, at 2:59 AM, Etienne Rivard wrote:

> Jonathan, I think I have found a way to do what I want to do. I  
> tested it and it works. It probably falls into the "ugly hack"  
> category, but I like it because it's really simple and seems to work  
> fine.

I'll need to go back and refresh myself on what you were trying to do,  
but thanks for sending this in.

> So, what I do is I include the line of code where I define the  
> equation inside the solution loop along with my self-made and very  
> basic Runge-Kutta-Fehlberg ODE solver. Which results in something  
> like:
:
:
> This probably won't beat any records of speed, but I'm not after  
> that for the moment.

Interesting. It won't much (any?) difference in speed, but I'd be  
inclined to write this as:

dSdt = Variable()
eq = TransientTerm() \
         == ImplicitDiffusionTerm(coeff=K/(c*rho*Snew**2)) \
         - ExponentialConvectionTerm(xi/Snew * dSdt) \
         - temp / Snew * dSdt
while res > tolRes:
    grad = (temp.getHarmonicFaceValue()[-1] -
            temp.getHarmonicFaceValue()[-2]) / dx
    dSdt.setValue(intRecRate(elapsed, Snew, grad))
    res = eq.sweep(var=temp,
                   boundaryConditions=BCs,
                   dt=dt,
                   solver=solver)
    grad = (temp.getHarmonicFaceValue()[-1]
            - temp.getHarmonicFaceValue()[-2]) / dx
    resODE = RKF45(lambda t, S: intRecRate(t, S, grad), 0, S, dt)

> Also, the use of french in your answers leads me to believe 2  
> things. First, you probably guessed my francophone background from  
> my name (sadly, maybe also my non-native english).

Your name gave you away. Your English is quite fine.

> That is very clever! Second, I like to think that you want to learn  
> some french.
> I would like to support this endeavour by correcting a tiny little  
> mistake. The word "dommage" is masculin. Therefore we say "Quel  
> dommage!"

Doumo onegaishimasu. While I have no problems with gender in Spanish,  
Italian, or Romanian, I pretty much gave up on it when it comes to  
French.