Hi,
Thank you for a very good program!
I am using FiPy to solve the heat equation in a cartesian geometry. I am
trying to set both a convective and a radiative boundery condition on the
right side of the geometry. I have done this by applying a source on the
boundary as follows:
maskRight = CellVariable(mesh, value=0.,unit="1")
maskRight.setValue(1, where=(mesh.getCellCenters()[0] > Lx - dx))
convectionOut = maskRight * (T - Tinf) * hAir / dx # [W/m^3]
radiationOut = maskRight * epsBoxOut * sigma * (T**4-Tinf**4) / dx
#[W/m^3]
source = heaterCellMask * dW #[W/m^3]
eqn = ImplicitDiffusionTerm(coeff=k) - convectionOut - radiationOut +
source == TransientTerm(coeff=cp*density)
while time < endTime:
T.updateOld()
residual = 100
while residual > desiredResidual:
residual = eqn.sweep(var=T,dt=timeStepDuration)
time += timeStepDuration;
I took this method from a post from 2006,*
http://www.mail-archive.com/[email protected]/msg00206.html .*My question is if
this works with the implicit solver since the boundary sources depends on
the temperature? I have also tried to use another way of representing the
convective boundary using an implicit source as follows (from this post
http://osdir.com/ml/python-fipy/2009-11/msg00045.html):
mask = mesh.getFacesRight()
outCoeff = (mask*[[hAir], [0]]).getDivergence()
convectionOut = ImplicitSourceTerm(coeff=outCoeff) - outCoeff * Tinf
The result is almost identical. But i just want to be on the save side, so
i don't run in to trouble later on. If this later method should be to
prefer for the implicit solver then i wonder how one would represent the
4:th power of the implicitSource when applying the radiative boundery? Or
maybe I should do this in some other way?
Best regards
Per Dahlbäck
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