This solution does work.Thank you.
On Wed, May 20, 2009 at 9:55 PM, Daniel Wheeler
<[email protected]>wrote:
>
> Try this:
>
> #!/usr/bin/env python
> from fipy import *
>
> ## my mesh and subdivisions and time variable
> Lx = 10.0
> Ly = 10.0
> Nx = 20.0
> Ny = 20.0
> Dx = Lx/Nx
> Dy = Ly/Ny
> t = Variable(value=0.0)
>
> ## create mesh
> m2D = Grid2D(nx=Nx, ny=Ny, dx=Dx, dy=Dy)
> x, y = m2D.getFaceCenters()
>
> ## define diffusion coefficients and different material along top edge of
> box
> nominalDiffusionCoef = 0.1
> D = FaceVariable(mesh=m2D, value=nominalDiffusionCoef)
> D.setValue(3 * nominalDiffusionCoef, where = (y > 9))
>
> ## define sources - not using at present
> ## boundarySource = FaceVariable(mesh=m2D, value = 0.0, rank=1)
> ## boundarySource.setValue(-1, where = m2D.getExteriorFaces() )
> ## other things I tried
> ## eq = TransientTerm() == ImplicitDiffusionTerm(coeff=D) + cv * t
> ## eq = TransientTerm() == ImplicitDiffusionTerm(coeff=D) +
> boundarySource.getDivergence()
>
> # Use the simple one
> eq = TransientTerm() == ImplicitDiffusionTerm(coeff=D)
>
> ## set up boundary conditions
> facesHeaters = (m2D.getFacesRight())
> # want flux to go to zero after a set time
> BCs = ( FixedFlux(faces=facesHeaters, value = -0.5 * (t < 3) ))
>
> phi = CellVariable(name = "solution variable",
> mesh = m2D,
> value = 1.0)
>
> dt = 0.9 * Dx*Dy / (2 * 1.0)
>
> ## setup viewer and end-time
> totalTime=10
> viewer=Viewer(vars=phi)
> viewer.plot()
>
> while t < totalTime:
> eq.solve(var=phi, boundaryConditions=BCs, dt=dt)
> viewer.plot()
> t.setValue(t.getValue()+dt)
> print t < 3, t ## check
>
> raw_input("Press <return> to proceed...")
>
>
> On Wed, May 20, 2009 at 12:11 AM, david wende <[email protected]>
> wrote:
> > Hi Gurus,
> >
> > This is a continuation of my attempts to model a bit of silicon being
> > heated by a pulse of laser.
> > I am also including the top metal layer as a change in diffusion coef.
> >
> > Modelling the heating by a FixedFlux along the right hand side, and would
> > like it to be non-zero before time T, and zero after time T.
> >
> > Eventually I would include some convection/radiation terms along
> > the other 3 sides, but that is not included yet (doing this bit by bit).
> >
> > I am having trouble making the flux go to zero. The signum function is
> > working and printing out OK, but it seems that when a BC has a time
> > dependent term, something goes wrong.
> >
> > Here is the code:
> >
> > #!/usr/bin/env python
> > from fipy import *
> > def signum ():
> > """ This returns 1 or 0 depending on time """
> >
> > if 3.0 > t:
> > return 1.0
> > else:
> > return 0.0
> >
> > ## my mesh and subdivisions and time variable
> > Lx = 10.0
> > Ly = 10.0
> > Nx = 20.0
> > Ny = 20.0
> > Dx = Lx/Nx
> > Dy = Ly/Ny
> > t = Variable(value=0.0)
> >
> > ## create mesh
> > m2D = Grid2D(nx=Nx, ny=Ny, dx=Dx, dy=Dy)
> > x, y = m2D.getFaceCenters()
> >
> > ## define diffusion coefficients and different material along top edge of
> > box
> > nominalDiffusionCoef = 0.1
> > D = FaceVariable(mesh=m2D, value=nominalDiffusionCoef)
> > D.setValue(3 * nominalDiffusionCoef, where = (y > 9))
> >
> > ## define sources - not using at present
> > ## boundarySource = FaceVariable(mesh=m2D, value = 0.0, rank=1)
> > ## boundarySource.setValue(-1, where = m2D.getExteriorFaces() )
> > ## other things I tried
> > ## eq = TransientTerm() == ImplicitDiffusionTerm(coeff=D) + cv * t
> > ## eq = TransientTerm() == ImplicitDiffusionTerm(coeff=D) +
> > boundarySource.getDivergence()
> >
> > # Use the simple one
> > eq = TransientTerm() == ImplicitDiffusionTerm(coeff=D)
> >
> > ## set up boundary conditions
> > facesHeaters = (m2D.getFacesRight())
> > # want flux to go to zero after a set time
> > BCs = ( FixedFlux(faces=facesHeaters, value = -0.5 * signum() ))
> >
> > phi = CellVariable(name = "solution variable",
> > mesh = m2D,
> > value = 1.0)
> >
> > dt = 0.9 * Dx*Dy / (2 * 1.0)
> >
> > ## setup viewer and end-time
> > totalTime=10
> > viewer=Viewer(vars=phi)
> > viewer.plot()
> >
> > while t() < totalTime:
> > eq.solve(var=phi, boundaryConditions=BCs, dt=dt)
> > viewer.plot()
> > t.setValue(t()+dt)
> > print signum(), t ## check
> >
> > raw_input("Press <return> to proceed...")
> >
> > Could you help?
> >
> > Thanks a lot
> >
> > --
> > David Wende
> > home +972-8-9353488
> > work +972-2-5886116
> > mobile +972-54-234-6479
> >
>
>
>
> --
> Daniel Wheeler
>
>
--
David Wende
home +972-8-9353488
work +972-2-5886116
mobile +972-54-234-6479
