mixed Dirichlet and Neumann boundary conditions for vector components

Asked by Nico Schlömer on 2013-05-02

I'd like to solve the Navier--Stokes equations for an axisymmetric flow u, and the boundary conditions at the rotational axis r=0 are typically given by

    u_r = 0
    du_z/dr = 0

where u_r, u_z are the components in r- and z-direction, respectively.

How would I implement this in Dolfin?

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DOLFIN Edit question
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Last query:
2013-05-03
Last reply:
2013-05-09

This question was reopened

Nico Schlömer (nschloe) said : #1

I just found https://answers.launchpad.net/dolfin/+question/144966 to answer the question.
Sorry for the noise!

Nico Schlömer (nschloe) said : #2

Okay, so I just bumped into the same issue again, with the exception that I need to enforce

    u_r = g
    du_z/dr = 0

along the boundary of a domain which happens not to align with a coordinate axis. The V.sub(d) trick from https://answers.launchpad.net/dolfin/+question/144966 doesn't apply anymore then. Any suggestion?

Anders Logg (logg) said : #3

FEniCS no longer uses Launchapd for Questions & Answers. Please
consult the documentation on the FEniCS web page for where and
how to (re)post your question: http://fenicsproject.org/support/

Anders Logg (logg) said : #4

FEniCS no longer uses Launchapd for Questions & Answers. Please
consult the documentation on the FEniCS web page for where and
how to (re)post your question: http://fenicsproject.org/support/

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