On Jan 14, 2008 8:56 PM, Gideon Simpson <[EMAIL PROTECTED]> wrote: > Related question for both incompressible flow and elasticity problems. > Suppose I have a plane of symmetry that will allow me to reduce my > computational domain. If > > \sigma_ij > > is the relevant stress tensor, then I will have that > > t^k_i \sigma_ij n_j = 0 > > where t^k is the k-th tangential vector of the local geometry. Physically, > this is vanishing shear stress. This is in addition to the condition > > u_i n_i = 0 > > for no normal flow (the slip condition). > > > Any thoughts on implementing the vanishing shear stress condition?
If we discretize with primitive variables and have Newtonian stress, this just amounts to a Neumann condition on the velocity. At bottom, Neumann conditions are just extra weak forms, so I think for more complicated constitutive relations, you just add the relevant weak form for the condition. Matt > -gideon > > On Jan 14, 2008, at 2:57 PM, Murtazo Nazarov wrote: > > > Is there an obvious high level way to implement normal flow type > boundary conditions or symmetry type boundary conditions? > > -gideon > > > > If you mean slip boundary condition which for normal velocity, it is > already implemented and soon will be available with UNICORN. > > The slip with friction is also implemented. > > /murtazo > > > > _______________________________________________ > DOLFIN-dev mailing list > [email protected] > http://www.fenics.org/mailman/listinfo/dolfin-dev > > > > > > > _______________________________________________ > DOLFIN-dev mailing list > [email protected] > http://www.fenics.org/mailman/listinfo/dolfin-dev > > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
