Boundary conditions definition by remapping with medcoupling

Local definitions

  /* Variables needed for boundary condition sub-selection */
  const cs_lnum_t n_b_faces = cs_glob_mesh->n_b_faces;

  /* MEDCoupling Remapper structure:
   * ------------------------------- */

  /* Number of fields to interpolate from the MED file */
  const int  nremapper_fields = 1;

  /* Names of the fields to read */
  const char  **field_names = NULL;
  BFT_MALLOC(field_names, nremapper_fields, const char *);
  field_names[0] = "TEMPERATURE";

Initialization of some variables

  /* Indexes needed to read the time step from the
   * file (-1, -1 if only one exists) */
  int it0 = -1;
  int it1 = -1;

Create a medcoupling remapper

  /* We request a remapper with a given name. If it does not exist,
   * the function returns a NULL pointer. */
  cs_medcoupling_remapper_t *r
    = cs_medcoupling_remapper_by_name_try("scalar_bc");

  /* If the returned pointer is NULL (first call), we create the
   * corresponding remapper */

  if (r == NULL) {

    /* Space dimension of the elements (2 for faces, 3 for cells) */
    int elts_dim = 2;

    /* Path to file */
    const char file_name[] = "/home/myname/study/2Dmap_Tfluid.med";

    /* The remapper is created. We retrieve its id from the function.
     * The function inputs are:
     * 1) Name of the remapper
     * 2) dimension of the mesh elements
     * 3) selection criteria for the boundary condition zone
     * 4) path to the med file
     * 5) number of fields to interpolate
     * 6) names of the fields to interpolate
     * 7 + 8) time iteration index and order */
    int r_id = cs_medcoupling_remapper_initialize("scalar_bc",
                                                  elts_dim,
                                                  "inlet",
                                                  file_name,
                                                  nremapper_fields,
                                                  field_names,
                                                  it0,
                                                  it1);

    /* Retrieve the pointer */
    r = cs_medcoupling_remapper_by_id(r_id);

    /* We create the interpolation matrix => Here it is only called once
     * since the mesh is not moving */
    cs_medcoupling_remapper_setup(r);

  }

Translate or rotate med data if needed

  if (false) {
    /* Translation using a tranlsation vector. Here it is (1, 0, 0) */
    cs_real_t translation_vector[3] = {1.0, 0.0, 0.0};
    cs_medcoupling_remapper_translate(r, translation_vector);

    /* Rotation using an invariant point, the rotation axis and rotation angle
       Here, center is O=(0,0,0) and z-axis (0,0,1). Angle is in radians, here
       it is ~pi/4 */
    cs_real_t rot_center[3] = {0.0, 0.0, 0.0};
    cs_real_t rot_axis[3] = {0.0, 0.0, 1.0};
    cs_real_t rot_angle = 0.7853981;

    cs_medcoupling_remapper_rotate(r, rot_center, rot_axis, rot_angle);

    /* Update of the interpolation matrix */
    cs_medcoupling_remapper_setup(r);
  }

We retrieve an array containing the interpolated values.

  /* We retrieve an array containing the interpolated values.
   * Inputs are:
   * 1) remapper
   * 2) id of the field to interpolate
   * 3) a default value (if no intersection is obtained) */
  cs_real_t *bc_scalar = cs_medcoupling_remapper_copy_values(r, 0, -5.0);

  /* We impose a dirichlet condition on all the faces of the boundary condition
   * related to the zone "inlet" */

We prescribe for the inlet a Dirichlet condition on the scalar "scalar1":

  const int keyvar = cs_field_key_id("variable_id");
  cs_field_t *scalar = cs_field_by_name_try("scalar1");
  int iscal = cs_field_get_key_int(scalar, keyvar) - 1;

  cs_lnum_t  nelts = 0;
  cs_lnum_t *lstelt = NULL;

  BFT_MALLOC(lstelt, n_b_faces, cs_lnum_t);

  cs_selector_get_b_face_list("inlet", &nelts, lstelt);

  for (cs_lnum_t ielt = 0; ielt < nelts; ielt++) {
    cs_lnum_t f_id = lstelt[ielt];

    icodcl[iscal*n_b_faces + f_id] = 1;
    rcodcl[iscal*n_b_faces + f_id] = bc_scalar[ielt];
  }

  BFT_FREE(lstelt);

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