Assembleur_P_DG.h

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#ifndef Assembleur_P_DG_included
#define Assembleur_P_DG_included
 
#include <Matrice_Morse_Sym.h>
#include <Assembleur_base.h>
#include <Domaine_DG.h>
#include <TRUST_Ref.h>
 
class Domaine_Cl_DG;
 
/**
 * @brief Assembles the pressure Laplacian matrix for the DG incompressible Navier-Stokes solver.
 *
 * This class builds the global pressure matrix arising from the SIP (Symmetric Interior
 * Penalty) DG discretization of the pressure Poisson problem. It is the pressure-space
 * counterpart of the diffusion operator assembly in Op_Diff_DG_Elem, but operates
 * directly on the pressure unknown without diffusivity weighting (nu = 1).
 *
 * The assembled matrix corresponds to the bilinear form:
 *   a(p_h, q_h) = sum_T  integral_T grad(p_h).grad(q_h)
 *               - sum_f  0.5 * integral_f { grad(p_h) }.n * [q_h]   (consistency)
 *               - sum_f  0.5 * integral_f [p_h] * { grad(q_h) }.n   (symmetry)
 *               + sum_f  (eta_F/h_T) * integral_f [p_h] * [q_h]     (penalty)
 *
 * where the sums run over all elements T and all faces f (internal and Dirichlet boundary).
 *
 * The matrix is stored as a Matrice_Morse (unsymmetric storage, though the assembled
 * system is symmetric by construction). The sparsity pattern couples each pressure DOF
 * to all pressure DOFs in the same element and in all face-neighbouring elements.
 *
 * Additionally, the class:
 *  - Stores a velocity-reconstruction matrix rec (Matrice_Morse) used by
 *    corriger_vitesses() to apply the pressure correction -grad(dP) to the velocity.
 *  - Handles pressure referencing via modifier_solution(), which pins the minimum
 *    pressure to zero when no Dirichlet pressure condition is imposed (has_P_ref == 0).
 *  - Provides a stub for quasi-compressible flows (assembler_QC) which is not yet
 *    fully implemented and aborts at runtime.
 *
 * @sa Op_Diff_DG_Elem, Op_Grad_DG, Assembleur_base
 */
class Assembleur_P_DG: public Assembleur_base
{
  Declare_instanciable(Assembleur_P_DG);
public:
  void associer_domaine_dis_base(const Domaine_dis_base&) override;
  void associer_domaine_cl_dis_base(const Domaine_Cl_dis_base&) override;
  const Domaine_dis_base& domaine_dis_base() const override;
  const Domaine_Cl_dis_base& domaine_Cl_dis_base() const override;
 
  int assembler(Matrice&) override;
  int assembler_rho_variable(Matrice&, const Champ_Don_base& rho) override;
  int assembler_QC(const DoubleTab&, Matrice&) override;
  int assembler_mat(Matrice&, const DoubleVect&, int incr_pression, int resoudre_en_u) override;
 
  int modifier_secmem(DoubleTab&) override;
  int modifier_solution(DoubleTab&) override;
 
  void completer(const Equation_base&) override;
  inline const Equation_base& equation() const { return mon_equation.valeur(); }
 
  /* corrige les vitesses pour une correction en pression donnee de type (-Cp, Cv) */
  void corriger_vitesses(const DoubleTab& dP, DoubleTab& dv) const override
  {
    rec.ajouter_multvect(dP, dv);
    dv.echange_espace_virtuel();
  }
 
protected:
  OBS_PTR(Equation_base) mon_equation;
  OBS_PTR(Domaine_DG) le_dom_dg_;
  OBS_PTR(Domaine_Cl_DG) le_dom_Cl_dg_;
 
  DoubleTab les_coeff_pression;
 
  int has_P_ref = 0;
  int stencil_done = 0;
 
  Matrice_Morse rec; //for reconstructing the velocities
};
 
#endif /* Assembleur_P_DG_included */