Op_Grad_DG.h

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#ifndef Op_Grad_DG_included
#define Op_Grad_DG_included
 
#include <Domaine_DG.h>
#include <Operateur_Grad.h>
#include <TRUST_Ref.h>
 
class Domaine_Cl_DG;
 
/**
 * @brief DG gradient operator acting on a DG pressure field to produce a velocity-space residual.
 *
 * This class implements the DG discretization of the pressure gradient operator used in
 * the incompressible Navier-Stokes momentum equation. It assembles the coupling between
 * pressure DOFs and velocity DOFs through the interface_blocs mechanism.
 *
 * The weak formulation integrates -grad(p_h) against velocity test functions v_h:
 *  - *Volume term*:        integral of grad(p_h) . v_h  (element-wise, by parts)
 *  - *Internal face term*: integral of {{p_h}} * [v_h . n]  (average-jump coupling)
 *
 * This formulation is the transpose of the divergence operator assembled by Op_Div_DG
 * in the continuous sense. However, Op_Grad_DG and Op_Div_DG use independent
 * implementations: Op_Grad_DG integrates grad(phi_p) . phi_v on element volumes and
 * {{phi_p}} * [phi_v . n] on faces, while Op_Div_DG integrates phi_p * div(phi_v) and
 * [phi_v . n] * {{phi_p}}. Both produce the same matrix up to a sign when the two
 * basis sets are compatible, but they are kept separate to allow independent tuning.
 *
 * @sa Op_Div_DG, Operateur_Grad_base
 */
class Op_Grad_DG: public Operateur_Grad_base
{
  Declare_instanciable(Op_Grad_DG);
public:
 
  void associer(const Domaine_dis_base&, const Domaine_Cl_dis_base&, const Champ_Inc_base&) override;
 
  inline int has_interface_blocs() const override { return 1; }
  void dimensionner_blocs(matrices_t matrices, const tabs_t& semi_impl = {}) const override;
 
  void ajouter_blocs(matrices_t matrices, DoubleTab& secmem, const tabs_t& semi_impl = { }) const override;
  DoubleTab& calculer(const DoubleTab&, DoubleTab&) const override;
  int impr(Sortie& os) const override;
 
protected:
  OBS_PTR(Domaine_DG) le_dom_DG;
  OBS_PTR(Domaine_Cl_DG) le_dcl_DG;
};
 
#endif /* Op_Grad_DG_included */