DOLFIN

Incompressible Navier Stokes demo

Asked by Dupront

Hello,

 I ran the channel demo for the instationary incompressible Navier-Stokes equations.
 It worked very fine.
 I wanted to run the driven cavity problem but I could not make it work.
 I only changed the definition of the mesh, it is a UnitSquare now
 and the dirichlet boundary conditions.
 In particular I don't have any pressure dirichlet condition on the boundary.

 What should I do to get it right ?
 Thank you.

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Anders Logg (logg) said : 		#1

On Wed, Oct 17, 2012 at 09:15:58AM -0000, Dupront wrote:
> New question #211443 on DOLFIN:
> https://answers.launchpad.net/dolfin/+question/211443
>
> Hello,
>
> I ran the channel demo for the instationary incompressible Navier-Stokes equations.
> It worked very fine.
> I wanted to run the driven cavity problem but I could not make it work.
> I only changed the definition of the mesh, it is a UnitSquare now
> and the dirichlet boundary conditions.
> In particular I don't have any pressure dirichlet condition on the boundary.
>
> What should I do to get it right ?
> Thank you.

What happens when you run the solver? I suspect the pressure Krylov
solver breaks down?

Try adding changing the pressure solve as follows:

  # Pressure correction
  begin("Computing pressure correction")
  b2 = assemble(L2)
  normalize(b2)
  [bc.apply(A2, b2) for bc in bcp]
  solve(A2, p1.vector(), b2, "gmres", prec)
  normalize(p1.vector())
  end()

--
Anders

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