[firedrake] RT/BDM works but not TH/VMS

[Colin Cotter]

Hi Justin,
  What is the form you are using for the VMS formulation?

all the best
--cjc

On 13 November 2015 at 19:21, Justin Chang <jychang48 at gmail.com> wrote:

> Hi all,
>
> So given this Darcy problem:
>
>   a = (dot(v, w) - p*div(w) - div(v)*q)*dx
>   L = f*q*dx
>
> where f = "12*pi*pi*sin(pi*x[0]*2)*sin(pi*x[1]*2)*sin(2*pi*x[2])" and with
> these solver options:
>
> 'ksp_type': 'gmres',
>     #'ksp_monitor_true_residual': True,
>     'pc_type': 'fieldsplit',
>     'pc_fieldsplit_type': 'schur',
>     'pc_fieldsplit_schur_fact_type': 'upper',
>     'pc_fieldsplit_schur_precondition': 'selfp',
>     'fieldsplit_0_ksp_type': 'preonly',
>     'fieldsplit_0_pc_type': 'bjacobi',
>     'fieldsplit_0_sub_pc_type': 'ilu',
>     'fieldsplit_1_ksp_type': 'preonly',
>     'fieldsplit_1_pc_type': 'hypre',
>     'fieldsplit_1_pc_hypre_type': 'boomerang'
>
> And without specifying any boundaries (my forcing function f is chosen so
> that the pressure is homogeneous on the boundary), RT0 and BDM works
> beautifully.
>
> However, with Taylor-Hood elements and VMS (which is equal order CG1 plus
> a least squares stabilization), the velocity works but the pressure
> solution is screwed up.
>
> Why is that?
>
> Thanks,
> Justin
>



-- 
http://www.imperial.ac.uk/people/colin.cotter

www.cambridge.org/9781107663916
-------------- next part --------------
HTML attachment scrubbed and removed