Hello,
For x*y, I do not mean the expressions of phi is x*y. Here I just use
x*y to sign discrete initial values to phi. My question has been solved.
But thank you all the same.
Regards
Ronghai
On 26/01/15 19:08, Fausto Arinos de A. Barbuto wrote:
Hello,
Can't you do this?
phi = CellVariable(mesh=mesh, hasOld=1, value=x*y)
phi2 = CellVariable(mesh=mesh, hasOld=1, value=(x*y)**2)
phi3 = CellVariable(mesh=mesh, hasOld=1, value=(x*y)**3)
eq = TransientTerm(var=phi, coeff=1.0e0) ==
ImplicitDiffusionTerm(var=phi, coeff=1.0e0) +
ImplicitDiffusionTerm(var=phi2, coeff=1.0e0) +
ImplicitDiffusionTerm(var=phi3, coeff=1.0e0)
At least, it works.
Regards,
Fausto
On Monday, January 26, 2015 3:10 PM, Ronghai Wu <[email protected]> wrote:
Dear Fipy developers and users,
I have a strange PDE in 2D "dphi/dt = Laplacian(phi) +
Laplacian(phi**2) + Laplacian(phi**3)",
which I implement in the following way, but raise typeerror "The
value of an `_OperatorVariable` cannot be assigned". Can anyone
help me? Thanks.
dx = 0.1
dy = dx
nx = 100
ny = nx
mesh = Grid2D(dx=dx, dy=dy, nx=nx, ny=ny)
x = mesh.cellCenters[0]
y = mesh.cellCenters[1]
phi = CellVariable(mesh=mesh, hasOld=1, value=x*y)
eq = TransientTerm(var=phi, coeff=1.) ==
ImplicitDiffusionTerm(var=phi, coeff=1.) +
ImplicitDiffusionTerm(var=phi**2, coeff=1.) +
ImplicitDiffusionTerm(var=phi**3, coeff=1.)
viewer = Viewer(vars=phi)
for step in range(10):
phi.updateOld()
res = 1.e5
while res > 1.e-1:
res = eq.sweep(dt=1.e-3)
viewer.plot()
Regards
Ronghai
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--
------------------------------------------
Ronghai Wu
Institute of Materials Simulation (WW8)
Department of Materials Science and Engineering
University of Erlangen-Nürnberg
Dr.-Mack-Str. 77, 90762 Fürth, Germany
Tel. +49 (0)911 65078-65064
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