V = VectorFunctionSpace(mesh,"CG",1) Q = FunctionSpace(mesh,"CG",1) W = V*Q v,p = TrialFunctions(W) w,q = TestFunctions(W) ... a = (dot(v, w) - p*div(w) - div(v)*q)*dx + 0.5*dot(v+grad(p),w+grad(q))*dx L = f*q*dx if that's what you're asking On Fri, Nov 13, 2015 at 1:48 PM, Colin Cotter <colin.cotter@imperial.ac.uk> wrote:
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@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
_______________________________________________ firedrake mailing list firedrake@imperial.ac.uk https://mailman.ic.ac.uk/mailman/listinfo/firedrake