7.2
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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);