ffc team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Wed, May 27, 2009 at 02:49:36PM -0500, Brandon Chabaud wrote:
> Hello,
> 
> I am trying to solve a Stokes flow type problem under the constraint that the
> integral over the domain of the pressure is zero.  None of the pde demos have
> an example of this.  How do I impose this condition in fenics?  Thanks.

Have you tried using the normalize() function in DOLFIN? It subtracts
the average of a vector from a vector so it has zero mean value. You
can use that on the right-hand side for the pressure to ensure that
the system has a solution and then again on the solution to obtain a
solution with zero mean value if necessary.

-- 
Anders

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