Thanks, I worked it out. But still have three questions: (1) The 4th-order is split by "psi = d2fdphi2(phi-phiold) + dfdphi - epsilon**2*laplace phi". I do not understand why we need d2fdphi2(phi-phiold)? (2) when solving the equation, sweep() controls the residual but solve() does not. I am wondering what this "residual" exactly is? it is the residual of what? (3) I noticed the recent issue "coupled 1D PDE on a periodic grid". I want to implement 2D periodic boundary condition. The question is, in addition to use PeriodicGrid2D(), should I do anything else to ensure the periodic boundary condition?
On 12/02/15 19:01, Guyer, Jonathan E. Dr. wrote: > Those figures were just copied over from > http://www.ctcms.nist.gov/fipy/examples/cahnHilliard/generated/examples.cahnHilliard.mesh2D.html > and represent a 1000x1000 mesh run to an elapsed time of 1000. > > The coupled example runs a 20x20 mesh up to t=0.05. You should be able to > manually increase the mesh size and the run time. Please be aware of the > problems cited in https://github.com/usnistgov/fipy/issues/378, however. > > We should make the figure consistent with the example, or make the example > consistent with mesh2D. Filed as https://github.com/usnistgov/fipy/issues/437. > > > On Feb 12, 2015, at 7:27 AM, Ronghai Wu <[email protected]> wrote: > >> Dear Fipy developers and users, >> >> I would like to split 4th-order DiffusionTerm into two 2nd-order. Taking the >> "examples.cahnHilliard.mesh2DCoupled" as example. >> >> http://www.ctcms.nist.gov/fipy/examples/cahnHilliard/generated/examples.cahnHilliard.mesh2DCoupled.html >> >> When running this example, I cannot get expected result as shown in the web. >> Instead, the \phi will diffuse out to 0.5. So, is there anything wrong with >> the code? If the splitting method is correct? Thanks. >> >> Regards >> Ronghai >> _______________________________________________ >> fipy mailing list >> [email protected] >> http://www.ctcms.nist.gov/fipy >> [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ] > > _______________________________________________ > fipy mailing list > [email protected] > http://www.ctcms.nist.gov/fipy > [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ] -- ------------------------------------------ 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 _______________________________________________ fipy mailing list [email protected] http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
