Jasper,
Namely, for my problem, I need the solution to the global Lagrange multipliers
during the assembly of the RHS. Hence, when looping over all cells during the
numerical integration, I need to always have access to the solution on, e.g.,
the first cell. How is this compatible with the parallel approach using
WorkStream presented in step-44, which I was hoping to use as a template?
In that case, determine the value of the Lagrange multiplier from the first
cell once, save it in a variable, and only then start the loop over all cells.
---------------------------
Alternatively, I thought about using AffineConstraints, where all DOFs
belonging to one Lagrange multiplier are constrained to the DOF with the
lowest index. In this case, I would pass the constraints object to
DoFTools::make_sparsity_pattern() hoping this might keep the size of the
stiffness matrix reasonably small:
constraints.clear()
ComponentMask mask = fe.component_mask(multipliers_fe);
const IndexSet dofs =
DoFTools::extract_dofs(dof_handler, mask);
const types::global_dof_index first_dof =
dofs.nth_index_in_set(0);
for (const types::global_dof_index i : dofs)
{
if (i != first_dof)
{
constraints.add_constraint(i, {{first_dof, 1.0}});
}
}
constraints.close()
How do you rate this second approach compared to the first one? Are there any
issues to be expected?
That would work too, if perhaps not the most efficient approach. It shouldn't
be terrible, though.
Best
W.
--
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Wolfgang Bangerth email: bange...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
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