Parameters settings for lagrangian module

Introduction

This page gives some examples of settings for the stochastic lagrangian module.

Lagrangian module

Particle tracking mode settings:

 
  /* Particle-tracking mode
   * ====================== */
 
  /* iilagr = CS_LAGR_OFF: no particle tracking (default)
   *        = CS_LAGR_ONEWAY_COUPLING: particle-tracking one-way coupling
   *        = CS_LAGR_TWOWAY_COUPLING: particle-tracking two-way coupling
   *        = CS_LAGR_FROZEN_CONTINUOUS_PHASE: particle tracking on frozen field
   *     (this option requires a calculation restart isuite=1,
   *     all Eulerian fields are frozen (pressure, velocities,
   *     scalars). This option is stronger than iccvfg)     */
 
  cs_glob_lagr_time_scheme->iilagr = CS_LAGR_ONEWAY_COUPLING;
 

In case of restart

 
  /* Particle-tracking calculation restart
   * ===================================== */
 
  /* isuila = 0 : no restart (default)
     = 1 : restart (this value requires a restart on the continuous
     phase too, i.e. isuite = 1)    */
 
  cs_glob_lagr_time_scheme->isuila = 0;
 
  /* Restart on volume and boundary statistics, and two-way coupling terms; */
  /* useful if isuila = 1 (defaul off: 0 ; on: 1)  */
 
  if (cs_glob_lagr_time_scheme->isuila == 1)
    cs_glob_lagr_stat_options->isuist = 0;
 

Specific models

 
  /* Particle tracking: specific models
   * ================================== */
 
  /* physical_model
   *  = CS_LAGR_PHYS_OFF: only transport modeling (default)
   *  = CS_LAGR_PHYS_HEAT: equation on temperature (in Celsius degrees),
   *    diameter or mass
   *  = CS_LAGR_PHYS_COAL: pulverized coal combustion
   *    (only available if the continuous phase is a flame of pulverized coal)
   */
 
  cs_glob_lagr_model->physical_model = CS_LAGR_PHYS_OFF;
 
  /* 3.1 equation on temperature, diameter or mass */
  if (cs_glob_lagr_model->physical_model == CS_LAGR_PHYS_HEAT) {
    /* equation on diameter */
    /* (default off: 0 ; on: 1)  */
    cs_glob_lagr_specific_physics->idpvar   = 0;
 
    /* equation on temperature (in Celsius degrees)  */
    /* (default off: 0 ; on: 1)  */
    /* This option requires a thermal scalar for the continuous phase.   */
    cs_glob_lagr_specific_physics->itpvar   = 0;
 
    /* equation on mass     */
    /* (default off: 0 ; on: 1)  */
    cs_glob_lagr_specific_physics->impvar   = 0;
  }
 

Example of coal fouling

 
  /* Coal fouling
   * ---------------------------------------------------------------------
   * Reference internal reports EDF/R&D: HI-81/00/030/A and HI-81/01/033/A
   *
   *  Evaluation of the probability for a particle to stick to a wall.
   *  This probability is the ratio of a critical viscosity on the
   *  viscosity of coal ashes
   *
   *           visref
   *  P(Tp) = --------      for viscen >= visref
   *           viscen
   *
   *        = 1             otherwise
   *
   *
   *  The expression of J.D. Watt and T.Fereday (J.Inst.Fuel-Vol42-p99)
   *  is used to evaluate the viscosity of the ashes
   *
   *                     Enc1 * 1.0d+7
   *  Log (10*viscen) = --------------- + Enc2
   *    10                           2
   *                    (Tp(C) - 150)
   *
   *  In literature, the range of the critical viscosity visref is between
   *  8 Pa.s and 1.D7 Pa.s For general purpose 1.0D+4 Pa.s is chosen
   *----------------------------------------------------------------------- */
 
  if (cs_glob_lagr_model->physical_model == CS_LAGR_PHYS_COAL) {
    /* iencra = 0 no fouling (default)
       = 1 fouling
       The boundary on which the fouling can occur must be specified with
       boundary condition definitions.
 
       * Post-processing:
       * iencnbbd = 1 / iencckbd = 1 (10.2) */
 
    cs_glob_lagr_model->fouling = 0;
 
    /* Example of definition of fouling criteria for each coal first
       (and single) coal icha = 1    */
    int icha = 0;
 
    /* tprenc : threshold temperature below which no fouling occurs
       (in degrees Celcius) */
    cs_glob_lagr_encrustation->tprenc[icha] = 600.0;
 
    /* visref : critical viscosity (Pa.s) */
    cs_glob_lagr_encrustation->visref[icha] = 10000.0;
 
    /* > coal composition in mineral matters:
       (with SiO2 + Al2O3 + Fe2O3 + CaO + MgO = 100% in mass)  */
    cs_real_t sio2  = 36.0;
    cs_real_t al2o3 = 20.8;
    cs_real_t fe2o3 = 4.9;
    cs_real_t cao   = 13.3;
 
    /* Enc1 and Enc2 : coefficients in Watt and Fereday expression  */
    cs_glob_lagr_encrustation->enc1[icha]
      = 0.00835 * sio2 + 0.00601 * al2o3 - 0.109;
    cs_glob_lagr_encrustation->enc2[icha]
      =  0.0415  * sio2 + 0.0192  * al2o3 + 0.0276 * fe2o3 + 0.016 * cao - 3.92;
  }
 

Calculation features for the dispersed phases

 
  /* Calculation features for the dispersed phases
   * ============================================= */
 
  /* Additional variables
   * --------------------
   *
   *   Additional variables may be accessed using the (CS_LAGR_USER + i)
   *   attribute, where 0 <= i < lagr_params->n_user_variables
   *   is the additional variable index.
   *
   *   The integration of the associated differential stochastic equation
   *   requires a user intervention in cs_user_lagr_sde() function */
 
  cs_lagr_set_n_user_variables(0);
 
  /* Steady or unsteady continuous phase
   * -----------------------------------
   *   if steady: isttio = 1
   *   if unsteady: isttio = 0
   *   if iilagr = CS_LAGR_FROZEN_CONTINUOUS_PHASE then isttio = 1
 
   Remark: if isttio = 0, then the statistical averages are reset
   at each time step   */
 
  if (cs_glob_lagr_time_scheme->iilagr != CS_LAGR_FROZEN_CONTINUOUS_PHASE)
    cs_glob_lagr_time_scheme->isttio   = 0;
 
  /* Two-way coupling: (iilagr = CS_LAGR_TWOWAY_COUPLING)
     ------------------------------ */
 
  if (cs_glob_lagr_time_scheme->iilagr == CS_LAGR_TWOWAY_COUPLING) {
    /* * number of absolute time step (i.e. with restart)
       from which a time average for two-way coupling source terms is
       computed (steady source terms)
       * if the time step is lower than NSTITS, source terms are
       unsteady: they are reset at each time step
       * useful only if ISTTIO = 1.
       * the min value for NSTITS is 1 */
 
    cs_glob_lagr_source_terms->nstits = 1;
 
    /* two-way coupling for dynamic (velocities and turbulent scalars) */
    /* (default off: 0; on: 1)  */
    /* (useful if ICCVFG = 0)    */
 
    cs_glob_lagr_source_terms->ltsdyn = 0;
 
    /* two-way coupling for mass,
       (if physical_model = CS_LAGR_PHYS_HEAT and impvar = 1)
       (default off: 0; on: 1) */
 
    if (   cs_glob_lagr_model->physical_model == CS_LAGR_PHYS_HEAT
        && (   cs_glob_lagr_specific_physics->impvar == 1
            || cs_glob_lagr_specific_physics->idpvar == 1))
      cs_glob_lagr_source_terms->ltsmas = 0;
 
    /* two-way coupling for thermal scalar
       (if physical_model = CS_LAGR_PHYS_HEAT and impvar = 1,
       or physical_model = CS_LAGR_PHYS_COAL)
       or for coal variables (if physical_model = CS_LAGR_PHYS_COAL)
       (default off: 0; on: 1) */
 
    if (   (   cs_glob_lagr_model->physical_model == CS_LAGR_PHYS_HEAT
            && cs_glob_lagr_specific_physics->itpvar == 1)
        || cs_glob_lagr_model->physical_model == CS_LAGR_PHYS_COAL)
      cs_glob_lagr_source_terms->ltsthe = 0;
 
  }
 

Example of volume statistics

 
  /* Volume statistics
     ----------------- */
 
  /* Threshold for the use of volume statistics
     ------------------------------------------
     * the value of the threshold variable is a statistical weight.
     * each cell of the mesh contains a statistical weight
     (sum of the statistical weights of all the particles
     located in the cell); threshold is the minimal value under
     which the contribution in statistical weight of a particle
     is ignored in the full model of turbulent dispersion and in the
     resolution of the Poisson equation for the correction of the
     mean velocities. */
 
  cs_glob_lagr_stat_options->threshold = 0.0;
 
  /* Calculation of the volume statistics from the absolute number
   * of time steps
   * * idstnt is a absolute number of time steps
   * (i.e. including calculation restarts) */
 
  cs_glob_lagr_stat_options->idstnt = 1;
 
  /* Steady calculation from the absolute time step nstist
   *   * nstist is a absolute number of time steps
   *     (i.e. including calculation restarts) from which the statistics
   *     are averaged in time.
   *   * useful if the calculation is steady (isttio=1)
   *   * if the number of time steps is lower than nstits,
   *     the transmitted source terms are unsteady (i.e. they are reset to
   *     zero at each time step)
   *   * the minimal value acceptable for nstist is 1.    */
 
  cs_glob_lagr_stat_options->nstist = cs_glob_lagr_stat_options->idstnt;
 
  /* Volume statistical variables
     ---------------------------- */
 
  /* Activation of the calculation of the particle volume fraction */
 
  cs_lagr_stat_activate(CS_LAGR_STAT_VOLUME_FRACTION);
 
  /* Activation of the calculation of the particle velocity */
 
  cs_lagr_stat_activate_attr(CS_LAGR_VELOCITY);
 
  /* Activation of the calculation of the particle residence time */
 
  cs_lagr_stat_activate_attr(CS_LAGR_RESIDENCE_TIME);
 
  /* Activation of the calculation of the weight */
 
  cs_lagr_stat_activate_attr(CS_LAGR_STAT_WEIGHT);
 
  /* Specific models (physical_model = CS_LAGR_PHYS_HEAT)
   * following the chosen options:
   *   Mean and variance of the temperature
   *   Mean and variance of the diameter
   *   Mean and variance of the mass
   */
 
  /* Statistics per class
   * -------------------- */
 
  cs_glob_lagr_model->n_stat_classes = 0;
 

Options concerning the numerical treatment of the dispersed phase

 
  /* Options concerning the numerical treatment of the dispersed phase
   * ================================================================= */
 
  /* Integration order of the stochastic differential equations */
 
  cs_glob_lagr_time_scheme->t_order = 1;
 
  /* Options concerning the treatment of the dispersed phase
   * ======================================================= */
 
  /* A value of 1 sets the assumption that we have regular particles.
     Since the turbulent dispersion model uses volume statistics,
     When modcpl=0 then the particles are assumed to be fluid particles
     and the turbulence dispersion model is disabled. */
 
  cs_glob_lagr_model->modcpl = 1;
 

Options concerning the treatment of specific forces

 
  /* Options concerning the treatment of specific forces
   * =================================================== */
 
  /* If dlvo = 1, DLVO deposition conditions are activated for the
     wall with appropriate condition type \ref CS_LAGR_DEPO_DLVO. */
 
  cs_glob_lagr_model->dlvo = 0;
 
  if (cs_glob_lagr_model->dlvo == 1) {
    /* Constants for the van der Waals forces
       --------------------------------------
       Hamaker constant for the particle/fluid/substrate system:*/
    cs_glob_lagr_physico_chemical->cstham = 6e-20;
 
    /* Retardation wavelength for the particle/fluid/substrate system:*/
    cs_glob_lagr_physico_chemical->lambda_vdw = 1000.0;
 
    /* Constants for the elecstrostatic forces
       ---------------------------------------
       Dielectric constant of the fluid (example: water at 293 K)*/
    cs_glob_lagr_physico_chemical->epseau = 80.1;
 
    /* Electrokinetic potential of the first solid - particle (Volt)*/
    cs_glob_lagr_physico_chemical->phi_p  = 0.05;
 
    /* Electrokinetic potential of the second solid - surface (Volt)*/
    cs_glob_lagr_physico_chemical->phi_s  =  -0.05;
 
    /* Valency of ions in the solution (used for EDL forces)*/
    cs_glob_lagr_physico_chemical->valen  = 1.0;
 
    /* Ionic force (mol/l)*/
    cs_glob_lagr_physico_chemical->fion   = 0.01;
  }
 

Brownian motion:

 
  /* Activation of Brownian motion
   * ============================= */
 
  /* Activation of Brownian motion:
     (default off: 0 ; on: 1)
     Caution: OPTION FOR DEVELOPERS ONLY
     ======== */
  cs_glob_lagr_brownian->lamvbr = 0;
 

Deposition model:

 
  /* Activation of deposition model
   * ============================== */
 
  /* Activation of the deposition model (default off: 0 ; on: 1) */
  cs_glob_lagr_model->deposition = 0;
 

Roughness resuspension model

 
  /* Activation of roughness and resuspension model
   * ============================================== */
 
  /* Activation of the resuspension model (default off: 0 ; on: 1) */
  cs_glob_lagr_model->resuspension = 0;
 
  /* Caution: OPTION FOR DEVELOPERS ONLY
     ========
     dlvo deposition conditions for roughness surface */
 
  cs_glob_lagr_model->roughness = 0;
 
  /* Parameters of the particle resuspension model for the roughness */
 
  /* average distance between two large-scale asperities */
  cs_glob_lagr_reentrained_model->espasg = 2e-05;
 
  /* density of the small-scale asperities */
  cs_glob_lagr_reentrained_model->denasp = 63600000000000.0;
 
  /* radius of small asperities */
  cs_glob_lagr_reentrained_model->rayasp = 5e-09;
 
  /* radius of large asperities */
  cs_glob_lagr_reentrained_model->rayasg = 2e-06;
 
  /* Young's modulus (GPa) */
  cs_glob_lagr_reentrained_model->modyeq = 266000000000.0;
 

Clogging model

 
  /* Activation of the clogging model
   * ================================ */
 
  /* Activation of the clogging model
     (default off: 0 ; on: 1)
     Caution: OPTION FOR DEVELOPERS ONLY
     ======== */
 
  cs_glob_lagr_model->clogging = 0;
 
  /* Parameters for the particle clogging model */
 
  /* Mean diameter*/
  cs_glob_lagr_clogging_model->diam_mean = 1.0e-6;
 
  /* Jamming limit */
  cs_glob_lagr_clogging_model->jamlim      = 0.74;
 
  /* Minimal porosity
   * from 0.366 to 0.409 for random packings
   * equal to 0.26 for close packings */
  cs_glob_lagr_clogging_model->mporos      = 0.366;
 
  /* Hamaker constant for the particle/fluid/particle system */
  cs_glob_lagr_clogging_model->csthpp      = 5e-20;
 

Deposit influence

 
  /* Influence of the deposit on the flow
   * ==================================== */
 
  /* Activation of the influence of the deposit on the flow
     by the head losses calculation (with clogging model only)
     (default off: 0 ; on: 1) */
 
  cs_glob_lagr_reentrained_model->iflow  = 0;
 
  if (cs_glob_lagr_reentrained_model->iflow == 1) {
 
    /* One-way coupling */
    cs_glob_lagr_time_scheme->iilagr  = CS_LAGR_ONEWAY_COUPLING;
 
    /* The statistical averages are not reset
       at each time step */
    cs_glob_lagr_time_scheme->isttio   = 1;
 
  }
 

Consolidation model:

 
  /* Activation of the consolidation model
   * ===================================== */
 
  /* Activation of the consolidation model
     (default off: 0 ; on: 1) */
 
  /* Caution: valid only for multilayer deposition: */
  if (cs_glob_lagr_model->clogging > 0)
    cs_glob_lagr_model->consolidation = 0;
 
  /* Parameters for the particle consolidation model */
 
  /* Consolidated height hconsol calculated using the deposit time
   * hconsol = t_depo * rconsol
   * Adhesion calculated using the following formula:
   * Fadh = F_consol + (F_DLVO - F_consol)
   *        * (0.5+0.5*tanh((h-hconsol)/kconsol/hconsol))
   */
 
  /* Consolidated force (N) */
  cs_glob_lagr_consolidation_model->force_consol = 3.0e-8;
 
  /* Slope of consolidation (->0 for a two-layer system) */
  cs_glob_lagr_consolidation_model->slope_consol = 0.1;
 
  /* Consolidation rate (m/s) */
  cs_glob_lagr_consolidation_model->rate_consol  = 4.0e-3;
 

Precipitation disolution model

 
  /* Activation of the precipitation/disolution model
   * ================================================ */
 
  /* Activation of the precipitation/dissolution model
     (default off: 0 ; on: 1)
     Caution: OPTION FOR DEVELOPERS ONLY */
  cs_glob_lagr_model->precipitation = 0;
 
  /* Diameter of particles formed by precipitation */
  cs_glob_lagr_precipitation_model->diameter = 2e-06;
 
  /* Diameter of particles formed by precipitation */
  cs_glob_lagr_precipitation_model->rho = 5200.0;
 
  /* Number of particle classes */
  cs_glob_lagr_precipitation_model->nbrclas = 2;
 

Boundary statistics

  /* Boundary statistics
   * =================== */
 
  /* Number of particle/boundary interactions
     (default off: 0 ; on: 1) */
  cs_glob_lagr_boundary_interactions->has_part_impact_nbr      = 1;
 
  /* Particle mass flux associated to particle/boundary interactions */
 
  cs_lagr_stat_activate(CS_LAGR_STAT_MASS_FLUX);
 
  cs_lagr_stat_activate_time_moment(CS_LAGR_STAT_MASS_FLUX,
                                    CS_LAGR_MOMENT_MEAN);
 
  /* Angle between particle velocity and the plane of the boundary face */
 
  cs_lagr_stat_activate(CS_LAGR_STAT_IMPACT_ANGLE);
 
  /* Norm of particle velocity during the integration with the boundary face;
     example: deactivate even if activated in GUI */
 
  cs_lagr_stat_deactivate(CS_LAGR_STAT_IMPACT_VELOCITY);
 
  /* (default off: 0 ; on: 1) */
  if (   cs_glob_lagr_model->physical_model == CS_LAGR_PHYS_COAL
      && cs_glob_lagr_model->fouling == 1) {
 
    /* Mass of fouled coal particles */
    cs_lagr_stat_activate(CS_LAGR_STAT_FOULING_MASS_FLUX);
 
    /* Diameter of fouled coal particles */
    cs_lagr_stat_activate(CS_LAGR_STAT_FOULING_DIAMETER);
 
    /* Coke fraction of fouled coal particles */
    cs_lagr_stat_activate(CS_LAGR_STAT_FOULING_COKE_FRACTION);
  }
 
  /* Add a user-defined boundary statistic:
     incident kinetic energy */
 
  for (int class = 0;
       class < cs_glob_lagr_model->n_stat_classes + 1;
       class++) {
 
    for (cs_lagr_stat_moment_t m_type = CS_LAGR_MOMENT_MEAN;
         m_type <= CS_LAGR_MOMENT_VARIANCE;
         m_type++) {
 
      cs_lagr_stat_event_define
        ("part_kinetic_energy",
         CS_MESH_LOCATION_BOUNDARY_FACES,
         -1,                        /* non predefined stat type */
         CS_LAGR_STAT_GROUP_TRACKING_EVENT,
         m_type,
         class,
         1,                         /* dimension */
         -1,                        /* component_id, */
         _incident_kinetic_energy,  /* data_func */
         NULL,                      /* data_input */
         _boundary_impact_weight,   /* w_data_func */
         NULL,                      /* w_data_input */
         0,
         -1,
         CS_LAGR_MOMENT_RESTART_AUTO);
 
    }
 
  }
 
  /* Name of the recordings for display,
     Average in time of particle average
     of the boundary statistics
     -----------------------------------*/
 
  /* The user intervenes only in the additional user information
     to be recorded: he must prescribe the name of the recording as well as
     the type of average that he wishes to apply to it for the writing
     of the log and the post-processing. */
 
  /* Frequency for the output of the Lagrangian log
   * ============================================== */
 
  cs_glob_lagr_log_frequency_n = 1;
 
  /* Post-process particle attributes
   * ================================ */
 
  cs_lagr_post_set_attr(CS_LAGR_STAT_CLASS, true);