Collision_Model_FT_base.cpp

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#include <EFichier.h>
#include <EcritureLectureSpecial.h>
#include <Probleme_FT_Disc_gen.h>
 
 
#include <type_traits>
#include <Collision_Model_FT_base.h>
 
// XD Collision_Model_FT_base objet_u Collision_Model_FT_base INHERITS_BRACE base for collision models for fluid
// XD_CONT particle interaction
Implemente_base_sans_constructeur(Collision_Model_FT_base,"Collision_Model_FT_base",Objet_U);
 
Collision_Model_FT_base::Collision_Model_FT_base()
{
  fictive_wall_coordinates_.resize(2*dimension);
}
Entree& Collision_Model_FT_base::readOn(Entree& is)
{
  Param p(que_suis_je());
  set_param(p);
  p.lire_avec_accolades_depuis(is);
  return is;
}
 
Sortie& Collision_Model_FT_base::printOn(Sortie& os) const
{
  Cerr << "Error::printOn is not implemented." << finl;
  Process::exit();
  return os;
}
 
void Collision_Model_FT_base::set_param(Param& p) const
{
  // could becom a param.dico
  p.ajouter_non_std("collision_model", (this),Param::REQUIRED); // XD_ADD_P chaine(into=["hybrid_esi","breugem"])
  // XD_CONT name of the collision model
 
  // needs to be done like the bloc_convection schema. Or simplify the syntax into some standard Param
  p.ajouter_non_std("detection_method", (this),Param::REQUIRED); // XD_ADD_P bloc_lecture
  // XD_CONT method to detect collisions
 
 
  p.ajouter("collision_duration", &collision_duration_, Param::REQUIRED); // XD_ADD_P double
  // XD_CONT duration of the collision in seconds;
 
  p.ajouter("activate_collision_before_impact", &is_collision_activated_before_impact_, Param::REQUIRED); // XD_ADD_P int
  // XD_CONT activate collision before impact (1) or not (0)
 
  p.ajouter("activation_distance_percentage_diameter", &activation_distance_percentage_diameter_, Param::REQUIRED); // XD_ADD_P double
  // XD_CONT activation distance of the collision process as a percentage of the particle diameter
 
  p.ajouter("force_on_two_phase_elem", &is_force_on_two_phase_elem_, Param::REQUIRED); // XD_ADD_P entier(into=[0,1],default=0)
  // XD_CONT force on two phase elements (1) or not (0). Only valid for a single particle.
}
 
int Collision_Model_FT_base::lire_motcle_non_standard(const Motcle& word, Entree& is)
{
  if (word=="collision_model")
    {
      Motcles words;
      words.add("hybrid_esi");
      words.add("breugem");
      Motcle secondword;
      is >> secondword;
      Cerr << "Reading collision_model attributes: " << secondword << finl;
      const int r = words.search(secondword);
      switch(r)
        {
        case 0:
          collision_model_ = Collision_model::HYBRID_ESI;
          break;
        case 1:
          collision_model_ = Collision_model::BREUGEM;
          break;
        default:
          Cerr << "Error " << words << "was expected whereas " << secondword <<
               " has been found."<< finl;
          Process::exit();
        }
      return 1;
    }
  else if (word=="detection_method")
    {
 
      Motcle openbrace ="{";
      Motcle closedbrace="}";
      Motcle secondword;
      is >> secondword;
      if (secondword==openbrace)
        {
          is >> secondword;
 
          Motcles words;
          words.add("check_all");
          words.add("verlet");
          words.add("lc_verlet");
          const int r = words.search(secondword);
          switch(r)
            {
            case 0:
              detection_method_ = Detection_method::CHECK_ALL;
              break;
            case 1:
              detection_method_ = Detection_method::VERLET;
              break;
            case 2:
              detection_method_ = Detection_method::LC_VERLET;
              break;
            default:
              Cerr << "Error " << words << "was expected whereas "
                   << secondword << " has been found."<< finl;
              Process::exit();
            }
 
          is >> secondword;
          while (secondword != closedbrace)
            {
              Motcles otherwords;
              otherwords.add("detection_thickness_Verlet");
              otherwords.add("nb_pas_dt_max_Verlet");
              int rang2 = otherwords.search(secondword);
              switch(rang2)
                {
                case 0:
                  is >> detection_thickness_Verlet_;
                  break;
                case 1:
                  is >> nb_dt_max_Verlet_;
                  break;
                default:
                  Cerr << "Collision_Model_FT_base::lire_motcle_non_standard\n"
                       << " options of collision_detection are:\n"
                       << otherwords;
                  Process::exit();
                }
              is >> secondword;
            }
        }
      return 1;
    }
  else
    {
      Cerr << word << " is not a keyword understood by " << que_suis_je() <<
           " in lire_motcle_non_standard"<< finl;
      Process::exit();
    }
  return -1;
}
 
void Collision_Model_FT_base::reset()
{
  const int nb_boundaries=2*dimension;
  F_old_.resize(nb_particles_tot_,nb_particles_tot_+nb_boundaries);
  F_now_.resize(nb_particles_tot_,nb_particles_tot_+nb_boundaries);
  e_eff_.resize(nb_particles_tot_,nb_particles_tot_+nb_boundaries);
  Cerr << "WARNING: Collision_Model_FT_base::reset of F_old_, F_now_, "
       "lagrangian_contact_forces_ and e_eff_." << finl;
}
 
int Collision_Model_FT_base::reprendre(Entree& is)
{
  Nom readword;
  const int format_xyz = EcritureLectureSpecial::is_lecture_special();
 
  is >> readword;
  if (readword != que_suis_je())
    {
      Cerr << "Error in Collision_Model_FT_base::reprendre\n";
      Cerr << "We was expecting " << que_suis_je();
      Cerr << "\n We found " << readword << finl;
      Process::exit();
    }
  is >> nb_particles_tot_;
  e_eff_.resize(nb_particles_tot_,nb_particles_tot_+2*dimension);
  F_old_.resize(nb_particles_tot_,nb_particles_tot_+2*dimension);
  if (format_xyz)
    {
      for (int i=0; i<F_old_.dimension(0); i++)
        for (int j=0; j<F_old_.dimension(1); j++)
          is>>F_old_(i,j);
      for (int i=0; i<e_eff_.dimension(0); i++)
        for (int j=0; j<e_eff_.dimension(1); j++)
          is>>e_eff_(i,j);
    }
  else
    {
      is>>F_old_;
      is>>e_eff_;
    }
  return 1;
}
 
int Collision_Model_FT_base::sauvegarder(Sortie& os) const
{
  int special, afaire;
  const int format_xyz = EcritureLectureSpecial::is_ecriture_special(special, afaire);
  int bytes = 0;
  if (format_xyz)
    {
      if (Process::je_suis_maitre())
        {
          os << Nom(que_suis_je()) << finl;
          os << nb_particles_tot_ << finl;
          for (int i=0; i<F_old_.dimension(0); i++)
            for (int j=0; j<F_old_.dimension(1); j++)
              os<<F_old_(i,j);
          for (int i=0; i<e_eff_.dimension(0); i++)
            for (int j=0; j<e_eff_.dimension(1); j++)
              os<<e_eff_(i,j);
        }
      return 0;
    }
  else
    {
      os << que_suis_je() << finl;
      os << nb_particles_tot_ << finl;
      os << F_old_;
      bytes += 8 * F_old_.size_array();
      os << e_eff_;
      bytes += 8 * e_eff_.size_array();
      return bytes;
    }
}
 
int Collision_Model_FT_base::preparer_calcul(const Domaine_VDF& domain_vdf,
                                             const int nb_particles_tot,
                                             const Navier_Stokes_FT_Disc& ns,
                                             const Transport_Interfaces_FT_Disc& eq_transport,
                                             const Schema_Comm& schema_comm_FT)
{
  set_geometric_parameters(domain_vdf);
  set_nb_particles_tot(nb_particles_tot);
  set_nb_real_particles(nb_particles_tot);
  resize_lagrangian_contact_force();
  resize_particles_collision_number();
  const Fluide_Diphasique& two_phase_elem=ns.fluide_diphasique();
  const int id_solid_phase=1-two_phase_elem.get_id_fluid_phase();
  const Solid_Particle_base& solid_particle=ref_cast(Solid_Particle_base,
                                                     two_phase_elem.fluide_phase(id_solid_phase));
  const double& diameter=solid_particle.get_equivalent_diameter();
  set_activation_distance(diameter);
  compute_fictive_wall_coordinates(diameter/2);
  associate_transport_equation(eq_transport);
 
  if (is_LC_activated())
    set_LC_zones(domain_vdf,schema_comm_FT);
 
  set_spring_properties(solid_particle);
 
  if ((F_old_.dimension(0)!=nb_particles_tot) ||
      (F_now_.dimension(0)!=nb_particles_tot) )
    reset();
 
  return 1;
}
 
void Collision_Model_FT_base::resize_geometric_parameters()
{
  domain_dimensions_.resize(dimension);
  nb_nodes_.resize(dimension);
  origin_.resize(dimension);
}
 
void Collision_Model_FT_base::set_spring_properties(const Solid_Particle_base& solid_particle)
{
  if (collision_duration_>0)
    {
      const double mass_sphere = solid_particle.get_mass();
      const double e_dry = solid_particle.get_e_dry();
      const double mass_eff_part_part = mass_sphere/2;
      const double mass_eff_wall_part = mass_sphere;
 
      stiffness_breugem_part_part_ = compute_stiffness_breugem(mass_eff_part_part,e_dry);
      stiffness_breugem_wall_part_ = compute_stiffness_breugem(mass_eff_wall_part,e_dry);
 
      if (collision_model_ == Collision_model::BREUGEM)
        {
          damper_breugem_part_part_ = compute_damper_breugem(mass_eff_part_part,e_dry);
          damper_breugem_wall_part_ = compute_damper_breugem(mass_eff_wall_part,e_dry);
        }
    }
}
 
void Collision_Model_FT_base::associate_transport_equation(const Equation_base& equation)
{
  const Transport_Interfaces_FT_Disc& eq = ref_cast(Transport_Interfaces_FT_Disc,equation);
  refequation_transport_ = eq;
}
 
void Collision_Model_FT_base::compute_fictive_wall_coordinates(const double& radius)
{
  DoubleVect offset_values(2*dimension);
 
  switch(is_collision_activated_before_impact_)
    {
    case 0:
      offset_values=0;
      break;
    case 1:
      if (activation_distance_>0) offset_values=activation_distance_;
      break;
    default:
      Cerr << "Collision_Model_FT_base::compute_fictive_wall_coordinates error"  <<finl;
      Process::exit();
      break;
    }
 
  // an offset is computed for the walls to activate the collision process before the impact
  fictive_wall_coordinates_(0) = origin_(0) - radius + offset_values(0);
  fictive_wall_coordinates_(1) = origin_(1) - radius + offset_values(1);
  fictive_wall_coordinates_(2) = origin_(2) - radius + offset_values(2);
  fictive_wall_coordinates_(3) = origin_(0) + domain_dimensions_(0) + radius - offset_values(3);
  fictive_wall_coordinates_(4) = origin_(1) + domain_dimensions_(1) + radius - offset_values(4);
  fictive_wall_coordinates_(5) = origin_(2) + domain_dimensions_(2) + radius - offset_values(5);
 
  Cerr << "fictive_wall_coordinates\n" << fictive_wall_coordinates_ << finl;
}
 
/*! @brief Recover the geometric parameters of the domain:
 * number of nodes in each direction
 * origin of the domain
 * dimensions of the domain
 */
void Collision_Model_FT_base::set_geometric_parameters(const Domaine_VDF& domaine_vdf)
{
  const Domaine& domain = domaine_vdf.domaine();
  const DoubleTab BB=domain.getBoundingBox();
  const Bords& bords=domain.faces_bord();
  DoubleVect NiNj(dimension); // NiNj=(NyNz NxNz NxNy )
  resize_geometric_parameters();
 
  // 1. Number of nodes per direction
  NiNj=0;
  for (int i=0; i<bords.nb_bords(); i++)
    {
      int  nb_boundary_faces = Process::check_int_overflow(mp_sum(ref_cast(Frontiere,bords(i)).nb_faces()));
      int nb_boundary_faces_local=ref_cast(Frontiere,bords(i)).nb_faces();
      if (nb_boundary_faces_local>0)
        {
          int face1=ref_cast(Frontiere,bords(i)).num_premiere_face();
          int orientation_face1=domaine_vdf.orientation(face1);
          NiNj(orientation_face1)=nb_boundary_faces;
        }
    }
  long long NxNy= static_cast<int>(mp_max(NiNj(2))) ;
  long long NxNz= static_cast<int>(mp_max(NiNj(1)));
  long long NyNz= static_cast<int>(mp_max(NiNj(0)));
 
  int Nx,Ny,Nz;
 
  Ny= NxNz>0 ? static_cast<int>(sqrt(NxNy*NyNz/NxNz)) : 0; // nb elem in the y-direction
  Nz= NxNy>0 ? static_cast<int>((NxNz*Ny/NxNy)) : 0; // nb elem in the z-direction, WARNING: operations order matter because Nz is an integer
  Nx= Ny>0 ? static_cast<int>(NxNy/Ny) : 0; // nb elem in the x-direction
 
  nb_nodes_(0)=Nx++; // nb nodes in the x-direction
  nb_nodes_(1)=Ny++; // nb nodes in the y-direction
  nb_nodes_(2)=Nz++; // nb nodes in the z-direction
 
  // 2. Origin and Domain_dimensions
  DoubleVect Origin(dimension);
  DoubleVect Domain_dimensions(dimension);
  Origin=0.;
  Domain_dimensions=0.;
 
  for (int j=0; j<dimension; j++)
    {
      double min_ = mp_min(BB(j,0));
      double max_ = mp_max(BB(j,1));
 
      Origin(j)=min_;
      Domain_dimensions(j)=max_-min_;
    }
 
  set_origin(Origin);
  set_domain_dimensions(Domain_dimensions);
 
  Cerr << "Origin " << Origin << finl;
  Cerr << "Domain length" << Domain_dimensions << finl;
  Cerr << "Nx Ny Nz " << nb_nodes_ << finl;
}
 
/*! @brief Check if two particles have the same ID
 * Very important function to stop computation if
 * two particles coalesce.
 */
int Collision_Model_FT_base::check_for_duplicates(ArrOfInt& vector)
{
  int flag =0;
  ArrOfInt copy_vector(vector);
  const int size = copy_vector.size_array();
  copy_vector.ordonne_array();
  for (int i = 0; i < size-1; i++)
    {
      if (copy_vector(i)==copy_vector(i+1))
        {
          flag = 1;
          Cerr << copy_vector(i) << " is duplicate !!" << finl ;
        }
    }
  return flag;
}
 
 
/* @brief we send the list of real particles to proc from lower zones
 */
ArrOfInt send_receive_list_id_particles(ArrOfInt& list_id_real_particles_to_send,
                                        const ArrOfInt& list_lower_zone,
                                        const Schema_Comm& schema_comm)
{
  ArrOfInt list_id_particle_recv;
  list_id_particle_recv.resize_array(0);
  //int nb_elem_recv=0;
  const int nb_real_particles_to_send=list_id_real_particles_to_send.size_array();
 
  schema_comm.begin_comm();
 
  for (int ind_pe_dest=0; ind_pe_dest<list_lower_zone.size_array(); ind_pe_dest++)
    {
      int PE_dest=list_lower_zone(ind_pe_dest);
      for(int ind_particle=0; ind_particle<nb_real_particles_to_send; ind_particle++)
        {
          const int id_particle=list_id_real_particles_to_send(ind_particle);
          assert(PE_dest!=Process::me());
          schema_comm.send_buffer(PE_dest) << id_particle;
        }
    }
 
  schema_comm.echange_taille_et_messages();
 
  const ArrOfInt& recv_pe_list = schema_comm.get_recv_pe_list();
  const int nb_recv_pe = recv_pe_list.size_array();
  for (int i=0; i<nb_recv_pe; i++)
    {
      const int pe_source = recv_pe_list[i];
      Entree& buffer = schema_comm.recv_buffer(pe_source);
      while(1)
        {
          int id_particle_recv=-1;
          buffer >> id_particle_recv;
          if (buffer.eof())
            break;
          if (id_particle_recv<0)
            Process::exit();
          //nb_elem_recv++;
          list_id_particle_recv.append_array(id_particle_recv);
        }
    }
  schema_comm.end_comm();
 
  return list_id_particle_recv;
}
 
 
void Collision_Model_FT_base::research_collision_pairs_Verlet(const Navier_Stokes_FT_Disc&
                                                              eq_ns,const Transport_Interfaces_FT_Disc& eq_transport)
{
  ArrOfInt list_particles_to_check_LC;
  const ArrOfInt& gravity_center_elem=eq_transport.get_gravity_center_elem();
  const Domaine_VF& domain_vf=ref_cast(Domaine_VF,eq_ns.domaine_dis());
  const int& nb_elem=domain_vf.nb_elem();
  const Maillage_FT_Disc& mesh=eq_transport.maillage_interface();
  const Schema_Comm& schema_comm=mesh.get_schema_comm_FT();
  const DoubleTab& particles_velocity=eq_transport.get_particles_velocity();
  const DoubleTab& particles_position=eq_transport.get_particles_position();
  const Fluide_Diphasique& two_phase_elem=eq_ns.fluide_diphasique();
  const int id_solid=1-two_phase_elem.get_id_fluid_phase();
  const auto& solid_particle=ref_cast(Solid_Particle_base,two_phase_elem.fluide_phase(id_solid));
  const double& radius=solid_particle.get_equivalent_radius();
  const Schema_Temps_base& time_scheme=eq_ns.schema_temps();
  const double& time_step=time_scheme.pas_de_temps();
 
  Cerr << "Update of Verlet tables - " ;
  // Step 1 : update of Linked Cells (for more info on the method, see X. Fang et al.,
  // J. Sound Vib., 2007).
  // Here, each linked cell match a CPU domain. We seed the id of real particles to LC
  // from lower zones (to receive LC from upper zones)
  if (detection_method_==Detection_method::LC_VERLET)
    {
      nb_real_particles_=0;
      list_real_particles_.resize_array(0);
      for (int particle=0; particle<nb_particles_tot_; particle++)
        {
          if (gravity_center_elem(particle)>-1 && gravity_center_elem(particle)<nb_elem)
            {
              list_real_particles_.append_array(particle);
              nb_real_particles_++;
            }
        }
      list_real_particles_.resize_array(nb_real_particles_);
 
      //Process::barrier(); // we wait that all procs have updated their list to do the exchange
      ArrOfInt list_virtual_particles;
      const ArrOfInt& list_lower_zone=get_list_lower_zone();
      list_virtual_particles=send_receive_list_id_particles(list_real_particles_,
                                                            list_lower_zone,
                                                            schema_comm);
      if (nb_real_particles_>0)
        {
          Cerr << "list_real_particles_ " << list_real_particles_<< finl;
          Cerr << "list_virtual_particles " << list_virtual_particles<< finl;
          list_particles_to_check_LC.resize(list_real_particles_.size_array()+
                                            list_virtual_particles.size_array());
          for (int k=0; k<list_real_particles_.size_array()
               +list_virtual_particles.size_array(); k++)
            {
              if (k<list_real_particles_.size_array()) list_particles_to_check_LC(k)=
                  list_real_particles_(k);
              else list_particles_to_check_LC(k)=
                  list_virtual_particles(k-list_real_particles_.size_array());
            }
          Cerr << "list_particles_to_check_LC " << list_particles_to_check_LC<< finl; // do not sort the list
        }
    }
  // ETAPE B : update of Verlet tables
  // we compute the distance between particles and we save the pairs that are within
  // the distance detection_thickness_Verlet_. I usually define it as 30% of the particle
  // diameter in the data file.
  // For Verlet table without LC, we test all particle pairs
  // For Verlet method with LC, for all real particles, we test all particles
  // pairs from the upper zone (proc domain + upper procs domain)
  double max_vi_glob=0;
  double max_vi=0.;
  if (nb_real_particles_>0)
    {
      Verlet_tables_=0;
      Verlet_tables_.dimensionner(nb_real_particles_);
 
      compute_Verlet_tables(particles_position,
                            particles_velocity,
                            max_vi,
                            radius,
                            list_particles_to_check_LC);
    }
  max_vi_glob=mp_max(max_vi); // with the linked cell method, we compute the max.
  // With only Verlet method,
  // there is no need to, but max_vi=mp_max(max_vi) for each proc.
  //  Computing the next Verlet table update time step based on the maximum velocity
  // of a particle in the domain
  int deltat_compute_min = (max_vi_glob>0) ?
                           static_cast<int>(floor((detection_thickness_Verlet_/(2*max_vi_glob))/
                                                  time_step)) :
                           nb_dt_max_Verlet_;
 
  nb_dt_compute_Verlet_=std::min(deltat_compute_min,nb_dt_max_Verlet_);
  Cerr << "Next update in " <<nb_dt_compute_Verlet_ << " time steps." << finl;
  nb_dt_Verlet_=0;
  // Cerr to check if Verlet tables are correctly filled
  if (nb_particles_tot_<20)
    {
      for (int ind_part_i=0; ind_part_i <nb_real_particles_; ind_part_i++)
        {
          Cerr << "Verlet_tables_["<<ind_part_i<<"].size() " << Verlet_tables_[ind_part_i].size() << " -- ";
          for (int ind_part_j=0; ind_part_j<Verlet_tables_[ind_part_i].size(); ind_part_j++)
            Cerr << " " << Verlet_tables_[ind_part_i][ind_part_j];
          Cerr << finl;
        }
    }
}
 
int Collision_Model_FT_base::get_last_id(const ArrOfInt& list_particles_to_check_LC)
{
  if (detection_method_==Detection_method::CHECK_ALL)
    Process::exit("Collision_Model_FT_base::get_last_id Should not be in here!");
  else if (detection_method_==Detection_method::VERLET)
    return nb_particles_tot_;
  else if(detection_method_==Detection_method::LC_VERLET)
    return(list_particles_to_check_LC.size_array());
  return 0;
}
 
 
int Collision_Model_FT_base::get_id(const ArrOfInt& list_particle, const int ind_id_particle)
{
  if (detection_method_==Detection_method::CHECK_ALL)
    Process::exit("Collision_Model_FT_base::get_id Should not be in here!");
  else if (detection_method_==Detection_method::VERLET)
    return(ind_id_particle);
  else if (detection_method_==Detection_method::LC_VERLET)
    return(list_particle(ind_id_particle));
  else
    Process::exit("Collision_Model_FT_base::get_id unkwnown detection_method_!");
  return 0;
}
 
int Collision_Model_FT_base::get_particle_j(const int ind_particle_i, const int ind_particle_j)
{
  if (detection_method_==Detection_method::CHECK_ALL)
    return(ind_particle_j);
  else if (detection_method_==Detection_method::VERLET ||
           detection_method_==Detection_method::LC_VERLET)
    return (Verlet_tables_[ind_particle_i][ind_particle_j]);
  return 0;
}
 
int Collision_Model_FT_base::get_nb_particles_j(const int ind_particle_i) const
{
  if (detection_method_==Detection_method::CHECK_ALL)
    return (nb_particles_tot_+2*dimension);
  else if (detection_method_==Detection_method::VERLET ||
           detection_method_==Detection_method::LC_VERLET)
    return (Verlet_tables_[ind_particle_i].size());
  return 0;
}
 
int Collision_Model_FT_base::get_particle_i(const int ind_particle_i)
{
  return(detection_method_==Detection_method::LC_VERLET ?
         list_real_particles_(ind_particle_i) : ind_particle_i);
}
 
int Collision_Model_FT_base::get_ind_start_particles_j(const int ind_particle_i) const
{
  return(detection_method_==Detection_method::CHECK_ALL ?
         (ind_particle_i+1) : 0);
}
 
 
void Collision_Model_FT_base::compute_Verlet_tables(const DoubleTab& particles_position,
                                                    const DoubleTab& particles_velocity,
                                                    double& max_vi,
                                                    const double& radius,
                                                    const ArrOfInt& list_particles_to_check_LC)
{
  int last_id = get_last_id(list_particles_to_check_LC);
  for (int ind_id_particle_i=0; ind_id_particle_i< nb_real_particles_; ind_id_particle_i++)
    {
      int id_particle_i=get_id(list_particles_to_check_LC,ind_id_particle_i);
      const double vi=fabs(sqrt(
                             pow(particles_velocity(id_particle_i,0),2) +
                             pow(particles_velocity(id_particle_i,1),2) +
                             pow(particles_velocity(id_particle_i,2),2)));
      if (vi>max_vi)
        max_vi=vi;
      // particle-particle distance
      for (int ind_id_particle_j=ind_id_particle_i+1; ind_id_particle_j< last_id; ind_id_particle_j++)
        {
          int id_particle_j= get_id(list_particles_to_check_LC, ind_id_particle_j);
          double dij=sqrt(
                       pow(particles_position(id_particle_j,0)-particles_position(id_particle_i,0),2) +
                       pow(particles_position(id_particle_j,1)-particles_position(id_particle_i,1),2) +
                       pow(particles_position(id_particle_j,2)-particles_position(id_particle_i,2),2));
 
          if ((dij-2*radius)<=detection_thickness_Verlet_)
            Verlet_tables_[ind_id_particle_i].add(id_particle_j);
 
        }
 
      // wall-particle distance
      for (int ind_wall=0; ind_wall<2*dimension; ind_wall++)
        {
          const int ori = ind_wall < dimension ? ind_wall : ind_wall - dimension;
          const double dij=fabs(fictive_wall_coordinates_(ind_wall)-
                                particles_position(id_particle_i,ori));
 
          if ((dij-2*radius)<=detection_thickness_Verlet_)
            Verlet_tables_[ind_id_particle_i].add(nb_particles_tot_+ind_wall);
        }
    }
}
 
 
void Collision_Model_FT_base::compute_dX_dU(DoubleTab& dX,
                                            DoubleTab& dU,
                                            const int& particle,
                                            const int& neighbor,
                                            const DoubleTab& particles_position,
                                            const DoubleTab& particles_velocity,
                                            const bool is_particle_particle_collision)
{
  if (is_particle_particle_collision)
    {
      for (int d = 0; d < dimension; d++)
        {
          dX(d) = particles_position(particle, d) - particles_position(neighbor, d);
          dU(d) = particles_velocity(particle, d) - particles_velocity(neighbor, d);
        }
    }
  else
    {
      int ind_wall = neighbor - nb_particles_tot_;
      int ori = ind_wall < dimension ? ind_wall : ind_wall - dimension;
      dX(ori) = particles_position(particle, ori) - fictive_wall_coordinates_(ind_wall);
      for (int d = 0; d < dimension; d++)
        dU(d) = particles_velocity(particle, d);
    }
}
 
DoubleTab Collision_Model_FT_base::compute_contact_force(
  const double& next_dist_int,
  const DoubleTab& norm,
  const DoubleTab& dUn,
  const int& particle_i,
  const int& particle_j,
  const int& is_compression_step,
  const double& is_collision_part_part)
{
  DoubleTab force_contact(dimension);
 
  if (collision_model_==Collision_model::HYBRID_ESI) // see Hamidi et al., IJMF, 2023.
    {
      const double e_eff_particle = is_compression_step ? 1 : e_eff_(particle_i, particle_j);
      const double stiffness = is_collision_part_part ? stiffness_breugem_part_part_:
                               stiffness_breugem_wall_part_;
      for (int d = 0; d < dimension; d++)
        force_contact(d)= -pow(e_eff_particle,2) * stiffness * next_dist_int * norm(d);
    }
  else if (collision_model_==Collision_model::BREUGEM) // See. W-P. Breugem, 2010.
    {
      const double stiffness = is_collision_part_part ? stiffness_breugem_part_part_:
                               stiffness_breugem_wall_part_;
      const double damper = is_collision_part_part ? damper_breugem_part_part_:
                            damper_breugem_wall_part_;
      for (int d = 0; d < dimension; d++)
        force_contact(d)= -stiffness*next_dist_int*norm(d) -damper*dUn(d);
    }
  else
    Process::exit("Collision_Model_FT_base::compute_contact_force unknown collision_model_");
 
  return force_contact;
}
 
void Collision_Model_FT_base::discretize_contact_forces_eulerian_field(
  const DoubleTab& volumic_phase_indicator_function,
  const Domaine_VF& domain_vf,
  const IntTab& particles_eulerian_id_number,
  DoubleTab& contact_force_source_term)
{
  Process::exit("Collision_Model_FT_base::discretize_contact_forces_eulerian_field "
                "not coded for particles of arbitrary shape");
}
 
bool Collision_Model_FT_base::is_Verlet_activated()
{
  if (detection_method_ == Detection_method::CHECK_ALL)
    return false;
  return true;
}
 
bool Collision_Model_FT_base::is_LC_activated()
{
  if (detection_method_ == Detection_method::LC_VERLET)
    return true;
  return false;
}
 
void Collision_Model_FT_base::set_LC_zones(const Domaine_VF& domain_vf, const Schema_Comm& schema_com)
{
  int nsup=0;
  int ninf=0;
 
  int nb_joints=domain_vf.nb_joints();
 
  double x0 = domain_vf.xp(0,0);
  double y0 = domain_vf.xp(0,1);
  double z0 = domain_vf.xp(0,2);
  double epsilon=1e-10;
  const int nb_elems=domain_vf.nb_elem();
  const int nb_elems_tot=domain_vf.nb_elem_tot();
 
  Cerr << "number or reals elements " << nb_elems << finl;
  Cerr << "total number of elements " << nb_elems_tot << finl;
  Cerr << "(x0 y0 z0) = (" << x0 << " " << y0 << " " << z0 << ")" << finl;
  Cerr << "joints number " << nb_joints << finl;
 
  // Firstly, every proc send coordinates of its first elem to other procs
  DoubleTabFT list_coord_recv(0,dimension);
  IntTabFT list_pe_recv(0);
  Cerr << "list_coord_recv.dimensions " << list_coord_recv.dimension(0) << " "
       << list_coord_recv.dimension(1) << finl;
  int nb_elem_recv=0;
 
  schema_com.begin_comm();
 
  for (int ind_pe_dest=0; ind_pe_dest<nb_joints; ind_pe_dest++)
    {
      const Joint& joint_temp = domain_vf.joint(ind_pe_dest);
      const int pe_dest = joint_temp.PEvoisin();
      assert(pe_dest!=Process::me());
      schema_com.send_buffer(pe_dest)  << x0 << y0 << z0;
    }
 
  schema_com.echange_taille_et_messages();
 
  const ArrOfInt& recv_pe_list = schema_com.get_recv_pe_list();
  const int nb_recv_pe = recv_pe_list.size_array();
  for (int i=0; i<nb_recv_pe; i++)
    {
      const int pe_source = recv_pe_list[i];
      Entree& buffer = schema_com.recv_buffer(pe_source);
      while(1)
        {
          double x0_rcv=-1, y0_rcv=-1, z0_rcv=-1;
          buffer >> x0_rcv >> y0_rcv >> z0_rcv;
          if (buffer.eof())
            break;
          nb_elem_recv++;
          list_coord_recv.append_line(x0_rcv,y0_rcv,z0_rcv);
          list_pe_recv.append_line(pe_source);
        }
    }
 
  schema_com.end_comm();
 
  list_coord_recv.resize(nb_elem_recv,dimension);
  list_pe_recv.resize(nb_elem_recv);
 
  if (nb_joints != nb_elem_recv) Process::exit("EB : Collision_Model_FT_base::"
                                                 "set_LC_zones -- erreur identification du 1er element"
                                                 " des procs de la zone de joint.");
  for(int ind_pe=0; ind_pe<nb_elem_recv; ind_pe++)
    {
      const int pe_voisin = list_pe_recv(ind_pe);
      double x0_joint =  list_coord_recv(ind_pe,0);
      double y0_joint =  list_coord_recv(ind_pe,1);
      double z0_joint =  list_coord_recv(ind_pe,2);
 
      if ( y0_joint>y0 || (fabs(y0_joint-y0)<epsilon && x0_joint>x0) ||
           ( fabs(x0_joint-x0) < epsilon && fabs(y0_joint-y0)<epsilon && (z0_joint>z0)) )
        list_upper_zone_.append_array(pe_voisin), nsup++;
      if ( y0_joint<=y0 && (fabs(y0_joint-y0)>=epsilon || x0_joint<=x0)
           && ( fabs(x0_joint-x0) >= epsilon || fabs(y0_joint-y0)>=epsilon
                || (z0_joint<=z0)) )
        list_lower_zone_.append_array(pe_voisin), ninf++;
 
    }
 
  list_upper_zone_.resize_array(nsup);
  list_lower_zone_.resize_array(ninf);
 
  Cerr << "list_upper_zone_ " << list_upper_zone_ << finl;
  Cerr << "list_lower_zone_ " << list_lower_zone_ << finl;
  Cerr << "max number of upper zone  = " << mp_max(nsup) << finl;
  Cerr << "max number of lower zone  = " << mp_max(ninf) << finl;
}
 
void Collision_Model_FT_base::add_collision(const int part_i, const int part_j, const bool is_part_part_collision)
{
  const double contrib=is_part_part_collision? 1 : .2; // for wall_particle_collision we add .2 (for post-processing)
  if (part_i<nb_particles_tot_)
    particles_collision_number_(part_i)+=contrib;
  if (part_j<nb_particles_tot_)
    particles_collision_number_(part_i)+=contrib;
}