#82: Some combinations of DiffusionTerm and ConvectionTerm do not work
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Reporter: wd15 | Owner:
Type: defect | Status: new
Priority: 1 | Component: None
Version: | Severity: Bugs
Keywords: |
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The following combinations seem to work correctly:
## works
eqn = UpwindConvectionTerm(coeff=convCoeff, diffusionTerm=-dTerm) == dTerm
##eqn = TransientTerm(1e-10) == UpwindConvectionTerm(coeff=-convCoeff,
diffusionTerm=dTerm) + dTerm
##eqn = 0 == UpwindConvectionTerm(coeff=-convCoeff, diffusionTerm=dTerm) +
dTerm
##eqn = 0 == -UpwindConvectionTerm(coeff=convCoeff, diffusionTerm=dTerm) +
dTerm
This is broken:
eqn = UpwindConvectionTerm(coeff=convCoeff, diffusionTerm=dTerm) == dTerm
It appears that the DiffusionTerm and ConvectionTerm need to be on the
same side of the equation. The following code demonstrates the problem:
from fipy import TransientTerm, UpwindConvectionTerm, DiffusionTerm,
Grid1D, CellVariable, VectorFaceVariable, numerix
from fipy import FixedValue, FaceVariable
mesh = Grid1D(nx=10, dx=1.)
var = CellVariable(mesh=mesh)
convCoeff = VectorFaceVariable(mesh=mesh)
convCoeff[:6]=-1e+6
diffCoeff = FaceVariable(mesh=mesh)
diffCoeff[6:]=1e+3
print convCoeff
print diffCoeff
BCs = (FixedValue(value=1., faces=mesh.getFacesRight()),
FixedValue(value=0., faces=mesh.getFacesLeft()))
dTerm = DiffusionTerm(1000)
## broken
##eqn = UpwindConvectionTerm(coeff=convCoeff, diffusionTerm=dTerm) ==
dTerm
## works
eqn = UpwindConvectionTerm(coeff=convCoeff, diffusionTerm=-dTerm) == dTerm
##eqn = TransientTerm(1e-10) == UpwindConvectionTerm(coeff=-convCoeff,
diffusionTerm=dTerm) + dTerm
##eqn = 0 == UpwindConvectionTerm(coeff=-convCoeff, diffusionTerm=dTerm) +
dTerm
##eqn = 0 == -UpwindConvectionTerm(coeff=convCoeff, diffusionTerm=dTerm) +
dTerm
eqn.solve(var, dt = 1e+10, boundaryConditions=BCs)
print var
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Ticket URL: <http://matdl-osi.org:9000/fipy/ticket/82>
FiPy <http://www.ctcms.nist.gov/fipy>
A Finite Volume PDE Solver Using Python
