vel_Laplace);
}
- // For the initialization of the matrices
- // that act on the pressure space it is worth
- // noticing one small detail. Since the
- // projection step involves the solution of a
- // Poisson equation with homogeneous Neumann
- // boundary conditions, we need somehow to
- // regularize this problem, that is to pick a
- // solution. The way we do it is by setting
- // the value of the pressure solution at the
- // first node (wherever it is) to zero. This
- // regularizes the problem and does not
- // increase the number of entries in the
- // sparsity pattern we use as the solution
- // shown in step-11 would do. In the end it
- // achieves the solution: it makes sure that
- // the pressure is not left undetermined up
- // to a constant.
+ // The initialization of the matrices
+ // that act on the pressure space is similar
+ // to the ones that act on the velocity space.
template <int dim>
void
NavierStokesProjection<dim>::initialize_pressure_matrices()