Advanced examples

Local variables common to following examples

The following declaration and initialization block is required used for the examples of this section:

  const cs_lnum_t n_b_faces = domain->mesh->n_b_faces;
 
  const int n_fields = cs_field_n_fields();
 
  /* Example of specific boundary conditions fully defined by the user,
   * on the basis of wall conditions.
   *
   * We prescribe for zone 'wall_s' a wall, with in addition:
   *   - a Dirichlet condition on velocity (sliding wall with no-slip condition)
   *   - a Dirichlet condition on the first scalar. */
 
  const cs_zone_t  *zn = nullptr;
 
  cs_field_t *scal = cs_field_by_name("scalar1");

Initialization and finalization

Initialization and finalization is similar to that of the base examples

Example 1

Example of specific boundary conditions fully defined by the user, on the basis of wall conditions selection (mass flow computation, specific logging, ...)

²We prescribe for zone 'wall_s' a wall, with in addition:

• a Dirichlet condition on velocity (sliding wall with no-slip condition)
• a Dirichlet condition on the first scalar.

  zn = cs_boundary_zone_by_name("wall_s");
 
  cs_real_t *vel_rcodcl1 = CS_F_(vel)->bc_coeffs->rcodcl1;
  cs_real_t *vel_rcodcl2 = CS_F_(vel)->bc_coeffs->rcodcl2;
  cs_real_t *vel_rcodcl3 = CS_F_(vel)->bc_coeffs->rcodcl3;
 
  for (cs_lnum_t ilelt = 0; ilelt < zn->n_elts; ilelt++) {
 
    const cs_lnum_t face_id = zn->elt_ids[ilelt];
 
    bc_type[face_id] = CS_SMOOTHWALL;
 
    scal->bc_coeffs->icodcl[face_id] = 1;
    CS_F_(vel)->bc_coeffs->icodcl[face_id] = 1;
 
    /* Dirichlet value */
 
    scal->bc_coeffs->rcodcl1[face_id] = 10.;
 
    vel_rcodcl1[n_b_faces*0 + face_id] = 1.;
    vel_rcodcl1[n_b_faces*1 + face_id] = 0.;
    vel_rcodcl1[n_b_faces*2 + face_id] = 0.;
 
    /* No exchange coefficient */
 
    scal->bc_coeffs->rcodcl2[face_id] = cs_math_infinite_r;
 
    vel_rcodcl2[n_b_faces*0 + face_id] = cs_math_infinite_r;
    vel_rcodcl2[n_b_faces*1 + face_id] = cs_math_infinite_r;
    vel_rcodcl2[n_b_faces*2 + face_id] = cs_math_infinite_r;
 
    /* Flux density at 0 */
 
    scal->bc_coeffs->rcodcl3[face_id] = 0;
 
    vel_rcodcl3[n_b_faces*0 + face_id] = 0;
    vel_rcodcl3[n_b_faces*1 + face_id] = 0;
    vel_rcodcl3[n_b_faces*2 + face_id] = 0;
 
  }

Example 2

Example of specific boundary conditions fully defined by the user, with no definition of a specific type.

We prescribe at zone 'surf_h' a homogeneous Neumann condition for all variables.

  zn = cs_boundary_zone_by_name("surf_h");
 
  for (cs_lnum_t ilelt = 0; ilelt < zn->n_elts; ilelt++) {
 
    const cs_lnum_t face_id = zn->elt_ids[ilelt];
 
    /* CAUTION: the value of bc_type must be assigned to CS_INDEF */
    bc_type[face_id] = CS_INDEF;
 
    for (int f_id = 0; f_id < n_fields; f_id++) {
 
      cs_field_t *f = cs_field_by_id(f_id);
      if (!(f->type & CS_FIELD_VARIABLE))
        continue;
 
      f->bc_coeffs->icodcl[face_id] = 3;
 
      for (cs_lnum_t ii = 0; ii < f->dim; ii++) {
        f->bc_coeffs->rcodcl1[n_b_faces*ii + face_id] = 0.;
        f->bc_coeffs->rcodcl2[n_b_faces*ii + face_id] = cs_math_infinite_r;
        f->bc_coeffs->rcodcl3[n_b_faces*ii + face_id] = 0.;
      }
    }
  }

Example 3

Example of wall boundary condition with automatic continuous switch between rough and smooth.

  zn = cs_boundary_zone_by_name("r_wall");
 
  if (cs_field_by_name_try("boundary_roughness") != nullptr) {
 
    cs_real_t *bpro_roughness = cs_field_by_name_try("boundary_roughness")->val;
 
    for (cs_lnum_t ilelt = 0; ilelt < zn->n_elts; ilelt++) {
 
      const cs_lnum_t face_id = zn->elt_ids[ilelt];
 
      bc_type[face_id] = CS_SMOOTHWALL;
 
      /* Boundary roughtness (in meter) */
      bpro_roughness[face_id] = 0.05;
    }
  }