On Feb 20, 2015, at 6:39 AM, Ronghai Wu <[email protected]> wrote: > (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)?
See the discussion on linearization of the source in http://www.ctcms.nist.gov/fipy/examples/phase/generated/examples.phase.simple.html You could write "psi = dfdphi - epsilon**2*laplace phi", but dfdphi would be a fully explicit source. By expanding source = source_old + d(source)/d(phi) (phi - phi_old) you get a more implicit version of the same term, with better convergence properties. _______________________________________________ fipy mailing list [email protected] http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
