Data setting for the 1D-wall thermal module (cs_user_1d_wall_thermal.cpp)

The cs_user_1d_wall_thermal_setup subroutine is used to set global parameters for the 1D-wall thermal module, and will soon replace the cs_user_1d_wall_thermal subroutine.

Postprocessing for the module thermal field can be activated as follows:

  cs_1d_wall_thermal_post_set_status(true);

To add a 1D wall thermal condition to a given boundary zone, one first needs to define in cs_user_1d_wall_thermal_setup the different parameters related to the zone.

First the zone to couple and number of layers in the 1D mesh:

  // Get pointer to boundary zone to couple
  const cs_zone_t *zone = cs_boundary_zone_by_name("BC_1");
 
  // Define a one layer 1D wall
  cs_1d_wall_thermal_add_zone(zone, 1);

Define the mesh parameters for each layer:

  // Define layer's mesh properties
  {
    const int layer_id = 0; /* layer id */
    const int n_pts = 8;    /* number of points in 1D mesh */
    const cs_real_t thickness = 0.01144; /* layer's thickness */
    const cs_real_t geom_factor = 1.;    /* mesh geometrical factor */
    cs_1d_wall_thermal_zone_define_layer_mesh(zone,
                                              layer_id,
                                              n_pts,
                                              thickness,
                                              geom_factor);
  }

Define layer's properties:

  {
    // Define layer's initial Temperature and physical properties
    const int layer_id = 0; /* layer id */
    const cs_real_t T_ini = 20.; /* Initial temperature in 1D wall */
    const cs_real_t lambda = 0.16; /* thermal conductivity */
    const cs_real_t rho = 900.; /* density */
    const cs_real_t Cp = 790.;  /* heat capacity */
    cs_1d_wall_thermal_zone_define_layer_properties_const(zone,
                                                          layer_id,
                                                          T_ini,
                                                          lambda, rho, Cp);
  }

And finally define a boundary condition, which is either a Dirichlet, Neumann or a Robin boundary condition:

  {
    // Define layer's Dirichlet boundary condition
    const cs_real_t Text = 70.; /* Exterior temperature */
    cs_1d_wall_thermal_zone_define_dirichlet_bc_const(zone, Text);
  }

  {
    // Define layer's Neumann boundary condition
    const cs_real_t phi_ext = 1000.; /* Exterior flux */
    cs_1d_wall_thermal_zone_define_neumann_bc_const(zone, phi_ext);
  }

  {
    // Define layer's Robin boundary condition
    const cs_real_t Text = 70.; /* Exterior temperature */
    const cs_real_t hext = 10.; /* Exterior exchange coefficient */
    cs_1d_wall_thermal_zone_define_robin_bc_const(zone, Text, hext);
  }

The cs_user_1d_wall_thermal subroutine, which is now deprecated, is used to set the 1D-wall thermal module parameters.

This function is called 3 times:

• A first call (iappel == 1) to count faces in the selected zones.
• A second call (iappel == 2) to initialize associated arrays.
• Subsequent calls (iappel == 3) at each time step to define and update additional arrays.

Local variables declaration

The values in this example should be defined for each call.

  cs_1d_wall_thermal_t *wall_thermal = cs_get_glob_1d_wall_thermal();

The restart behavior of this module can be modified by adapting the following snippet:

  wall_thermal->use_restart = cs_restart_present() ? true : false;

Associatation with boundary zones.

For the first and second initialization passes (iappel = 1 or 2), the associated faces must be determined.

At the first pass, the faces must simply be counted. At the second pass, the list of associated faces is actually set.

The following code illustrates how this can be handled.

  if (iappel == 1 || iappel == 2) {
 
    /*-------------------------------------------------------------------------*
     * Faces determining with the 1-D thermal module:
     *----------------------------------------------
     *
     * nfpt1d    : Total number of faces with the 1D thermal module
     * ifpt1d[ii]: Number of the [ii]th face with the 1D thermal module
 
     * Remarks:
     *--------
     * During the rereading of the restart file, nfpt1d and ifpt1d are
     * compared with the other values from the restart file being the result of
     * the start or restarting computation.
     *
     * A total similarity is required to continue with the previous computation.
     * Regarding the test case on ifpt1d, it is necessary that the array be
     * arranged in increasing order (ifpt1[jj] > ifpt1d[ii] if jj > ii).
     *
     * If it is impossible, contact the developer team to deactivate this test.
     *-------------------------------------------------------------------------*/
 
    /* Get the list of boundary faces that will be coupled */
 
    cs_lnum_t nlelt = 0;
    cs_array<cs_lnum_t> lstelt(cs_glob_mesh->n_b_faces);
 
    cs_selector_get_b_face_list("2 or 3 or 5 or 6 or 7 or 8 or 9 or 10",
                                &nlelt, lstelt);
 
    if (iappel == 1) {
      wall_thermal->nfpt1d = nlelt;
    }
    else if (iappel == 2) {
      /* Fill the ifpt1d array */
      cs_lnum_t ifbt1d = 0;
      for (cs_lnum_t ilelt = 0 ; ilelt < nlelt ; ilelt++) {
        cs_lnum_t ifac = lstelt[ilelt];
        wall_thermal->ifpt1d[ifbt1d] = ifac+1;
        ifbt1d++;
      }
    }
 
  }
 

Thermal model setup.

At the second initialization pass (iappel 2), the number of discretization points along each 1d segment, their distribution (based on a geometric progression ratio), the wall thickness, and initial temperature must also be defined:

For the second initialization pass (iappel 2), The list of associated faces is actualley set. Also, the number of discretization points along each 1d segment, their distribution (based on a geometric progression ratio), the wall thickness, and initial temperature must also be defined.

  /*--------------------------------------------------------------------------*
   * Parameters padding of the mesh and initialization:
   *--------------------------------------------------
   *
   * (Only one pass during the beginning of the computation)
 
   * local_models[ii].nppt1d: number of discretized points associated
   *   to the (ii)th face with the 1-D thermal module.
   * local_models[ii].eppt1d: wall thickness associated to the (ii)th face
   *   with the 1-D thermal module.
   * local_models[ii].rgpt1d: geometric progression ratio of the
   *   meshing refinement associated to the (ii)th face with the
   *   1-D thermal module. (with : rgpt1d > 1 => small meshes on the fluid side)
   * local_models[ii].tppt1d: wall temperature initialization associated to the
   *   (ii)th face with the 1-D thermal module.
 
   * Remarks:
   *--------
   * During the rereading of the restart file for the 1-D thermal module,
   * the tppt1d variable is not used.
   *
   * The nfpt1d, eppt1d and rgpt1d variables are compared to the previous
   * values being the result of the restart file.
   *
   * An exact similarity is necessary to continue with the previous computation.
   *---------------------------------------------------------------------------*/
 
  if (iappel == 2) {
    for (cs_lnum_t ii = 0 ; ii < wall_thermal->nfpt1d ; ii++) {
      wall_thermal->local_models[ii].nppt1d = 8;
      wall_thermal->local_models[ii].eppt1d = 0.01144;
      wall_thermal->local_models[ii].rgpt1d = 1.;
      wall_thermal->tppt1d[ii] = cs_glob_fluid_properties->t0;
    }
  }

Computation

In the solution steps, the solid thermal properties and boundary conditions can be updated at each time step, where the function is called with parameter iappel = 3.

  /*--------------------------------------------------------------------------*
   * Padding of the wall exterior boundary conditions:
   *-------------------------------------------------
   *
   * local_models[ii].iclt1d: boundary condition type
   * ------------
   * local_models[ii].iclt1d = 1: dirichlet condition,
   *                               with exchange coefficient
   * local_models[ii].iclt1d = 3: flux condition
   *
   * local_models[ii].tept1d: exterior temperature
   * local_models[ii].hept1d: exterior exchange coefficient
   * local_models[ii].fept1d: flux applied to the exterior (flux<0 = coming flux)
   * local_models[ii].xlmt1d: lambda wall conductivity coefficient (W/m/C)
   * local_models[ii].rcpt1d: wall coefficient rho*Cp (J/m3/C)
   * local_models[ii].dtpt1d: time step resolution of the thermal equation
   *                          to the (ii)th boundary face with the
   *                          1-D thermal module (s)
   *--------------------------------------------------------------------------*/
 
  if (iappel == 3) {
 
    const cs_lnum_t *b_face_cells = cs_glob_mesh->b_face_cells;
    const cs_real_3_t *cdgfbo = cs_glob_mesh_quantities->b_face_cog;
 
    const auto cpro_dt = CS_F_(dt)->get_val_s();
    for (cs_lnum_t ii = 0 ; ii < wall_thermal->nfpt1d ; ii++) {
      wall_thermal->local_models[ii].iclt1d = 1;
      wall_thermal->local_models[ii].tept1d = cs_glob_fluid_properties->t0;
      /* Physical parameters */
      cs_lnum_t face_id = wall_thermal->ifpt1d[ii] - 1;
      /* Floor: plate */
      if (cdgfbo[face_id][2] <= 1.e-3) {
        wall_thermal->local_models[ii].xlmbt1 = 0.16;
        wall_thermal->local_models[ii].rcpt1d = 790.*900.;
      /* Wall and ceiling: marinite */
      }
      else {
        wall_thermal->local_models[ii].xlmbt1 = 0.11;
        wall_thermal->local_models[ii].rcpt1d = 670.*778.;
      }
      cs_lnum_t c_id = b_face_cells[face_id];
      wall_thermal->local_models[ii].dtpt1d = cpro_dt[c_id];
    }
 
  }