User extra operations for the Lagrangian module

Introduction

This page provides an example that may be used or adapted to perform extra or advanced extra-operations within the Lagrangian module.

Example

First we initialize some variables:

 
  cs_lagr_particle_set_t  *p_set = cs_lagr_get_particle_set();
  const cs_lagr_attribute_map_t *p_am = p_set->p_am;
 

In the next example we compute the particle mass flow rate on 4 planes

 
  {
    cs_real_t zz[4] = {0.1e0, 0.15e0, 0.20e0, 0.25e0};
 
    /* If we are in an unsteady case, or if the beginning of the steady stats
     * is not reached yet, all statistics are reset to zero at each time
     step before entering this function.*/
 
    if(   cs_glob_lagr_time_scheme->isttio == 0
       || cs_glob_time_step->nt_cur <= cs_glob_lagr_stat_options->nstist) {
      for (cs_lnum_t iplan = 0; iplan < 4; iplan++)
        _m_flow[iplan] = 0.0;
 
    }
 
    for (cs_lnum_t iplan = 0; iplan < 4; iplan++) {
 
      for (cs_lnum_t npt = 0; p_set->n_particles; npt++) {
 
        unsigned char *part = p_set->p_buffer + p_am->extents * npt;
 
        cs_lnum_t iel = cs_lagr_particle_get_lnum(part, p_am, CS_LAGR_CELL_ID);
 
        const cs_real_t *part_coords
          = cs_lagr_particle_attr_const(part, p_am, CS_LAGR_COORDS);
        const cs_real_t *prev_part_coords
          = cs_lagr_particle_attr_n_const(part, p_am, 1, CS_LAGR_COORDS);
 
        if (    part_coords[0] > zz[iplan]
            && prev_part_coords[0] <= zz[iplan])
          _m_flow[iplan] +=  cs_lagr_particle_get_real(part, p_am,
                                                       CS_LAGR_STAT_WEIGHT)
                           * cs_lagr_particle_get_real(part, p_am,
                                                       CS_LAGR_MASS);
 
      }
 
    }
 
    cs_real_t stat_age = cs_lagr_stat_get_age();
 
    for (int iplan = 0; iplan < 4; iplan++)
      bft_printf(" Particle mass flow at Z(%d): %e14.5)",
                 iplan,
                 _m_flow[iplan]/stat_age);
  }