Thank you very much! On Tue, Jul 24, 2018 at 10:13 AM Daniel Wheeler <daniel.wheel...@gmail.com> wrote:
> On Wed, Jul 18, 2018 at 4:36 PM, Daniel DeSantis <desan...@gmail.com> > wrote: > > > > > > If I wanted to run this in a cylindrical coordinate grid, the equation > would become: > > > > > > Can I just call the following in FiPy to account for this coordinate > system change?: > > > > mesh = CylindricalGrid1D(nx = 100.,Lx = 1., dx = 1./100.) > > Yes, that should work. There is a bug (see > https://github.com/usnistgov/fipy/issues/547) when calculating > gradients, but I don't think that applies to diffusion terms. > > Jon, is that correct? > > > If not, how do I account for the dependent variable when it is not in > the differential? Essentially, how do can I put lambda/r in the coefficient > etc.? > > You can multiply through by r and then split the transient term into > an implicit TransientTerm and a source term. It gives an extra source > term that is dependent on the time step. > > > 2) Is the correct way to add a source term simply to write something > like: > > > > eq = TransientTerm() == DiffusionTerm() + S > > > > or > > > > eq = TransientTerm() == DiffusionTerm() + ImplicitSourceTerm(S)? > > Either one. ImplicitSourceTerm implies that the source term is "var * > S", not "S" only, but the "var" is the variable that you're solving > for. To use ImplicitSourceTerm the S should be negative. In your case, > the source does not depend on temperature so you can't use an > ImplicitSourceTerm. > > > 3) Regarding boundary conditions, I am trying to use a boundary > condition that has my dependent variable (T) in the boundary condition. The > condition is dT/dr = h(T - Tc), where Tc is a constant. Would this be the > correct way to do that? I'm mostly inquiring about writing the dependent > variable as T.faceValue... > > > > T.faceGrad.constrain(h*(T.faceValue - Tc), mesh.facesLeft) > > I think that should work. Test it carefully. It's never obvious to me > what the sign should be. Don't trust it though. > > -- > Daniel Wheeler > > _______________________________________________ > fipy mailing list > fipy@nist.gov > http://www.ctcms.nist.gov/fipy > [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ] > -- Daniel DeSantis
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