No need to apologize. I'm glad you were able to find the information you were looking for.
As [noted here](https://www.ctcms.nist.gov/fipy/examples/diffusion/generated/examples.diffusion.mesh1D.html?highlight=gradient) the normal component of the boundary gradients are zero by default. You can see the non-zero tangential components in this simple example: ``` import fipy as fp mesh = fp.Grid2D(nx=1, ny=2) var = fp.CellVariable(mesh=mesh, value=[1, 2]) fp.Viewer(vars=var.faceGrad).plot() ``` ________________________________________ From: fipy-boun...@nist.gov <fipy-boun...@nist.gov> on behalf of M.J. Bogdan <mjb...@cam.ac.uk> Sent: Thursday, August 8, 2019 5:12 AM To: FIPY Subject: Re: Is faceGrad at boundaries assumed zero by default, or only its component normal to the boundary? All right, I've found the information, so sorry for engaging you. Best regards, Michal On 2019-08-03 14:47, M.J. Bogdan wrote: > Hello, > > I am slightly confused by the default boundary Neumann condition of > faceGrad. I have found a mention in one of the previous e-mail threads > here that faceGrad is assumed 0 by default on mesh boundaries, for any > variable (I have failed to locate any mention of this in the > documentation, but will be happy to be pointed to a relevant piece > there). Is that precisely correct? Or is only the faceGrad component > normal to boundary that is set to 0 by default? > > Best regards, > > Michal > > > > > _______________________________________________ > fipy mailing list > fipy@nist.gov > http://www.ctcms.nist.gov/fipy > [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ] _______________________________________________ fipy mailing list fipy@nist.gov http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ] _______________________________________________ fipy mailing list fipy@nist.gov http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
