void
compute_nearnullspace(std::vector<NumericVector<Number> *> & sp, NonlinearImplicitSystem & sys)
{
FEProblemBase * p =
sys.get_equation_systems().parameters.get<FEProblemBase *>("_fe_problem_base");
p->computeNearNullSpace(sys, sp);
}
void
compute_bounds(NumericVector<Number> & lower,
NumericVector<Number> & upper,
NonlinearImplicitSystem & sys)
{
FEProblemBase * p =
sys.get_equation_systems().parameters.get<FEProblemBase *>("_fe_problem_base");
p->computeBounds(sys, lower, upper);
}
void
compute_jacobian(const NumericVector<Number> & soln,
SparseMatrix<Number> & jacobian,
NonlinearImplicitSystem & sys)
{
FEProblemBase * p =
sys.get_equation_systems().parameters.get<FEProblemBase *>("_fe_problem_base");
p->computeJacobianSys(sys, soln, jacobian);
}
void
compute_postcheck(const NumericVector<Number> & old_soln,
NumericVector<Number> & search_direction,
NumericVector<Number> & new_soln,
bool & changed_search_direction,
bool & changed_new_soln,
NonlinearImplicitSystem & sys)
{
FEProblemBase * p =
sys.get_equation_systems().parameters.get<FEProblemBase *>("_fe_problem_base");
p->computePostCheck(
sys, old_soln, search_direction, new_soln, changed_search_direction, changed_new_soln);
}
void petscSetupDampers(NonlinearImplicitSystem& sys)
{
FEProblem * problem = sys.get_equation_systems().parameters.get<FEProblem *>("_fe_problem");
NonlinearSystem & nl = problem->getNonlinearSystem();
PetscNonlinearSolver<Number> * petsc_solver = dynamic_cast<PetscNonlinearSolver<Number> *>(nl.sys().nonlinear_solver.get());
SNES snes = petsc_solver->snes();
#if PETSC_VERSION_LESS_THAN(3,3,0)
// PETSc 3.2.x-
SNESLineSearchSetPostCheck(snes, dampedCheck, problem);
#else
// PETSc 3.3.0+
SNESLineSearch linesearch;
#if PETSC_VERSION_LESS_THAN(3,4,0)
PetscErrorCode ierr = SNESGetSNESLineSearch(snes, &linesearch);
#else
PetscErrorCode ierr = SNESGetLineSearch(snes, &linesearch);
#endif
CHKERRABORT(problem->comm().get(),ierr);
ierr = SNESLineSearchSetPostCheck(linesearch, dampedCheck, problem);
CHKERRABORT(problem->comm().get(),ierr);
#endif
}
// Jacobian assembly function for the Laplace-Young system
void LaplaceYoung::jacobian (const NumericVector<Number>& soln,
SparseMatrix<Number>& jacobian,
NonlinearImplicitSystem& sys)
{
// Get a reference to the equation system.
EquationSystems &es = sys.get_equation_systems();
// Get a constant reference to the mesh object.
const MeshBase& mesh = es.get_mesh();
// The dimension that we are running
const unsigned int dim = mesh.mesh_dimension();
// Get a reference to the NonlinearImplicitSystem we are solving
NonlinearImplicitSystem& system =
es.get_system<NonlinearImplicitSystem>("Laplace-Young");
// A reference to the \p DofMap object for this system. The \p DofMap
// object handles the index translation from node and element numbers
// to degree of freedom numbers. We will talk more about the \p DofMap
// in future examples.
const DofMap& dof_map = system.get_dof_map();
// Get a constant reference to the Finite Element type
// for the first (and only) variable in the system.
FEType fe_type = dof_map.variable_type(0);
// Build a Finite Element object of the specified type. Since the
// \p FEBase::build() member dynamically creates memory we will
// store the object as an \p UniquePtr<FEBase>. This can be thought
// of as a pointer that will clean up after itself.
UniquePtr<FEBase> fe (FEBase::build(dim, fe_type));
// A 5th order Gauss quadrature rule for numerical integration.
QGauss qrule (dim, FIFTH);
// Tell the finite element object to use our quadrature rule.
fe->attach_quadrature_rule (&qrule);
// Here we define some references to cell-specific data that
// will be used to assemble the linear system.
// We begin with the element Jacobian * quadrature weight at each
// integration point.
const std::vector<Real>& JxW = fe->get_JxW();
// The element shape functions evaluated at the quadrature points.
const std::vector<std::vector<Real> >& phi = fe->get_phi();
// The element shape function gradients evaluated at the quadrature
// points.
const std::vector<std::vector<RealGradient> >& dphi = fe->get_dphi();
// Define data structures to contain the Jacobian element matrix.
// Following basic finite element terminology we will denote these
// "Ke". More detail is in example 3.
DenseMatrix<Number> Ke;
// This vector will hold the degree of freedom indices for
// the element. These define where in the global system
// the element degrees of freedom get mapped.
std::vector<dof_id_type> dof_indices;
// Now we will loop over all the active elements in the mesh which
// are local to this processor.
// We will compute the element Jacobian contribution.
MeshBase::const_element_iterator el = mesh.active_local_elements_begin();
const MeshBase::const_element_iterator end_el = mesh.active_local_elements_end();
for ( ; el != end_el; ++el)
{
// Store a pointer to the element we are currently
// working on. This allows for nicer syntax later.
const Elem* elem = *el;
// Get the degree of freedom indices for the
// current element. These define where in the global
// matrix and right-hand-side this element will
// contribute to.
dof_map.dof_indices (elem, dof_indices);
// Compute the element-specific data for the current
// element. This involves computing the location of the
// quadrature points (q_point) and the shape functions
// (phi, dphi) for the current element.
fe->reinit (elem);
// Zero the element Jacobian before
// summing them. We use the resize member here because
// the number of degrees of freedom might have changed from
// the last element. Note that this will be the case if the
// element type is different (i.e. the last element was a
// triangle, now we are on a quadrilateral).
Ke.resize (dof_indices.size(),
dof_indices.size());
// Now we will build the element Jacobian. This involves
// a double loop to integrate the test funcions (i) against
// the trial functions (j). Note that the Jacobian depends
// on the current solution x, which we access using the soln
// vector.
//
for (unsigned int qp=0; qp<qrule.n_points(); qp++)
{
Gradient grad_u;
for (unsigned int i=0; i<phi.size(); i++)
grad_u += dphi[i][qp]*soln(dof_indices[i]);
const Number
sa = 1. + grad_u*grad_u,
K = 1. / std::sqrt(sa),
dK = -K / sa;
for (unsigned int i=0; i<phi.size(); i++)
for (unsigned int j=0; j<phi.size(); j++)
Ke(i,j) += JxW[qp]*(
K * (dphi[i][qp]*dphi[j][qp]) +
dK * (grad_u*dphi[j][qp]) * (grad_u*dphi[i][qp]) +
_kappa * phi[i][qp] * phi[j][qp]
);
}
dof_map.constrain_element_matrix (Ke, dof_indices);
// Add the element matrix to the system Jacobian.
jacobian.add_matrix (Ke, dof_indices);
}
// That's it.
}
// Residual assembly function for the Laplace-Young system
void LaplaceYoung::residual (const NumericVector<Number>& soln,
NumericVector<Number>& residual,
NonlinearImplicitSystem& sys)
{
EquationSystems &es = sys.get_equation_systems();
// Get a constant reference to the mesh object.
const MeshBase& mesh = es.get_mesh();
// The dimension that we are running
const unsigned int dim = mesh.mesh_dimension();
libmesh_assert_equal_to (dim, 2);
// Get a reference to the NonlinearImplicitSystem we are solving
NonlinearImplicitSystem& system =
es.get_system<NonlinearImplicitSystem>("Laplace-Young");
// A reference to the \p DofMap object for this system. The \p DofMap
// object handles the index translation from node and element numbers
// to degree of freedom numbers. We will talk more about the \p DofMap
// in future examples.
const DofMap& dof_map = system.get_dof_map();
// Get a constant reference to the Finite Element type
// for the first (and only) variable in the system.
FEType fe_type = dof_map.variable_type(0);
// Build a Finite Element object of the specified type. Since the
// \p FEBase::build() member dynamically creates memory we will
// store the object as an \p UniquePtr<FEBase>. This can be thought
// of as a pointer that will clean up after itself.
UniquePtr<FEBase> fe (FEBase::build(dim, fe_type));
// A 5th order Gauss quadrature rule for numerical integration.
QGauss qrule (dim, FIFTH);
// Tell the finite element object to use our quadrature rule.
fe->attach_quadrature_rule (&qrule);
// Declare a special finite element object for
// boundary integration.
UniquePtr<FEBase> fe_face (FEBase::build(dim, fe_type));
// Boundary integration requires one quadraure rule,
// with dimensionality one less than the dimensionality
// of the element.
QGauss qface(dim-1, FIFTH);
// Tell the finte element object to use our
// quadrature rule.
fe_face->attach_quadrature_rule (&qface);
// Here we define some references to cell-specific data that
// will be used to assemble the linear system.
// We begin with the element Jacobian * quadrature weight at each
// integration point.
const std::vector<Real>& JxW = fe->get_JxW();
// The element shape functions evaluated at the quadrature points.
const std::vector<std::vector<Real> >& phi = fe->get_phi();
// The element shape function gradients evaluated at the quadrature
// points.
const std::vector<std::vector<RealGradient> >& dphi = fe->get_dphi();
// Define data structures to contain the resdual contributions
DenseVector<Number> Re;
// This vector will hold the degree of freedom indices for
// the element. These define where in the global system
// the element degrees of freedom get mapped.
std::vector<dof_id_type> dof_indices;
// Now we will loop over all the active elements in the mesh which
// are local to this processor.
// We will compute the element residual.
residual.zero();
MeshBase::const_element_iterator el = mesh.active_local_elements_begin();
const MeshBase::const_element_iterator end_el = mesh.active_local_elements_end();
for ( ; el != end_el; ++el)
{
// Store a pointer to the element we are currently
// working on. This allows for nicer syntax later.
const Elem* elem = *el;
// Get the degree of freedom indices for the
// current element. These define where in the global
// matrix and right-hand-side this element will
// contribute to.
dof_map.dof_indices (elem, dof_indices);
// Compute the element-specific data for the current
// element. This involves computing the location of the
// quadrature points (q_point) and the shape functions
// (phi, dphi) for the current element.
fe->reinit (elem);
// We use the resize member here because
// the number of degrees of freedom might have changed from
// the last element. Note that this will be the case if the
// element type is different (i.e. the last element was a
// triangle, now we are on a quadrilateral).
Re.resize (dof_indices.size());
// Now we will build the residual. This involves
// the construction of the matrix K and multiplication of it
// with the current solution x. We rearrange this into two loops:
// In the first, we calculate only the contribution of
// K_ij*x_j which is independent of the row i. In the second loops,
// we multiply with the row-dependent part and add it to the element
// residual.
for (unsigned int qp=0; qp<qrule.n_points(); qp++)
{
Number u = 0;
Gradient grad_u;
for (unsigned int j=0; j<phi.size(); j++)
{
u += phi[j][qp]*soln(dof_indices[j]);
grad_u += dphi[j][qp]*soln(dof_indices[j]);
}
const Number K = 1./std::sqrt(1. + grad_u*grad_u);
for (unsigned int i=0; i<phi.size(); i++)
Re(i) += JxW[qp]*(
K*(dphi[i][qp]*grad_u) +
_kappa*phi[i][qp]*u
);
}
// At this point the interior element integration has
// been completed. However, we have not yet addressed
// boundary conditions.
// The following loops over the sides of the element.
// If the element has no neighbor on a side then that
// side MUST live on a boundary of the domain.
for (unsigned int side=0; side<elem->n_sides(); side++)
if (elem->neighbor(side) == NULL)
{
// The value of the shape functions at the quadrature
// points.
const std::vector<std::vector<Real> >& phi_face = fe_face->get_phi();
// The Jacobian * Quadrature Weight at the quadrature
// points on the face.
const std::vector<Real>& JxW_face = fe_face->get_JxW();
// Compute the shape function values on the element face.
fe_face->reinit(elem, side);
// Loop over the face quadrature points for integration.
for (unsigned int qp=0; qp<qface.n_points(); qp++)
{
// This is the right-hand-side contribution (f),
// which has to be subtracted from the current residual
for (unsigned int i=0; i<phi_face.size(); i++)
Re(i) -= JxW_face[qp]*_sigma*phi_face[i][qp];
}
}
dof_map.constrain_element_vector (Re, dof_indices);
residual.add_vector (Re, dof_indices);
}
// That's it.
}