libMesh
element_postprocess.C
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1 // General libMesh includes
2 #include "libmesh/libmesh_common.h"
3 #include "libmesh/elem.h"
4 #include "libmesh/fe_base.h"
5 #include "libmesh/fem_context.h"
6 #include "libmesh/point.h"
7 #include "libmesh/quadrature.h"
8 
9 // Local includes
10 #include "L-shaped.h"
11 
12 // Bring in everything from the libMesh namespace
13 using namespace libMesh;
14 
15 // Define the postprocess function to compute QoI 0, the integral of the the solution
16 // over a subdomain
18 {
19  FEMContext & c = cast_ref<FEMContext &>(context);
20 
21  FEBase * elem_fe = libmesh_nullptr;
22  c.get_element_fe(0, elem_fe);
23 
24  // Element Jacobian * quadrature weights for interior integration
25  const std::vector<Real> & JxW = elem_fe->get_JxW();
26  const std::vector<Point> & xyz = elem_fe->get_xyz();
27 
28  // The number of local degrees of freedom in each variable
29  unsigned int n_qpoints = c.get_element_qrule().n_points();
30 
31  // The function R = int_{omega} T dR
32  // omega is a subset of Omega (the whole domain), omega = [0.75, 1.0] x [0.0, 0.25]
33  Number dQoI_0 = 0.;
34 
35  // Loop over quadrature points
36  for (unsigned int qp = 0; qp != n_qpoints; qp++)
37  {
38  // Get co-ordinate locations of the current quadrature point
39  const Real x = xyz[qp](0);
40  const Real y = xyz[qp](1);
41 
42  // If in the sub-domain omega, add the contribution to the integral R
43  if (std::abs(x - 0.875) <= 0.125 && std::abs(y - 0.125) <= 0.125)
44  {
45  // Get the solution value at the quadrature point
46  Number T = c.interior_value(0, qp);
47 
48  // Update the elemental increment dR for each qp
49  dQoI_0 += JxW[qp] * T;
50  }
51  }
52 
53  // Update the computed value of the global functional R, by adding the contribution from this element
54  computed_QoI[0] = computed_QoI[0] + dQoI_0;
55 }
double abs(double a)
This class provides all data required for a physics package (e.g.
Definition: diff_context.h:54
const class libmesh_nullptr_t libmesh_nullptr
void get_element_fe(unsigned int var, FEGenericBase< OutputShape > *&fe) const
Accessor for interior finite element object for variable var for the largest dimension in the mesh...
Definition: fem_context.h:262
The libMesh namespace provides an interface to certain functionality in the library.
Number interior_value(unsigned int var, unsigned int qp) const
Definition: fem_context.C:326
PetscErrorCode Vec x
virtual void element_postprocess(DiffContext &context)
Does any work that needs to be done on elem in a postprocessing loop.
This class provides all data required for a physics package (e.g.
Definition: fem_context.h:61
DIE A HORRIBLE DEATH HERE typedef LIBMESH_DEFAULT_SCALAR_TYPE Real
const QBase & get_element_qrule() const
Accessor for element interior quadrature rule for the dimension of the current _elem.
Definition: fem_context.h:765
unsigned int n_points() const
Definition: quadrature.h:113
This class forms the foundation from which generic finite elements may be derived.