face_to_elem_VDF.h

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#ifndef face_to_elem_VDF_included
#define face_to_elem_VDF_included
 
#include <Domaine_VF.h>
 
/*! @brief Interpolates a face-based field (nf_tot, N) to an element-based
 *         field (ne_tot, N, D) using face normals and surfaces.
 *         Each element value is the average of the contributions from its faces.
 */
inline void face_to_elem_VDF(const Domaine_VF& domaine, const DoubleTab& tab_faces, DoubleTab& tab_elems)
{
  const IntTab& elem_faces = domaine.elem_faces();
  const DoubleTab& nf = domaine.face_normales();
  const DoubleVect& fs = domaine.face_surfaces();
  const int nb_face_elem = elem_faces.line_size();
  const int ne_tot = domaine.nb_elem_tot();
  const int N = tab_faces.line_size();
  const int D = Objet_U::dimension;
  assert(tab_elems.dimension_tot(0) == ne_tot && tab_faces.dimension_tot(0) == domaine.nb_faces_tot());
 
  tab_elems = 0.;
  for (int ele = 0; ele < ne_tot; ele++)
    for (int n = 0; n < N; n++)
      for (int d = 0; d < D; d++)
        for (int s = 0; s < nb_face_elem; s++)
          {
            const int f = elem_faces(ele, s);
            if (fs[f] > 1.e-12)
              tab_elems(ele, n, d) += tab_faces(f, n) * nf(f, d) / fs[f];
          }
 
  tab_elems *= 0.5;
}
 
#endif /* face_to_elem_VDF_included */