/usr/share/code_saturne/user_examples/cs_user_lagr_particle.c is in code-saturne-data 4.3.3+repack-1build1.
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This file is part of Code_Saturne, a general-purpose CFD tool.
Copyright (C) 1998-2016 EDF S.A.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 51 Franklin
Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/*----------------------------------------------------------------------------*/
/*============================================================================
* Functions dealing with particle tracking
*============================================================================*/
#include "cs_defs.h"
/*----------------------------------------------------------------------------
* Standard C library headers
*----------------------------------------------------------------------------*/
#include <limits.h>
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <ctype.h>
#include <float.h>
#include <assert.h>
/*----------------------------------------------------------------------------
* Local headers
*----------------------------------------------------------------------------*/
#include "bft_printf.h"
#include "bft_error.h"
#include "bft_mem.h"
#include "fvm_periodicity.h"
#include "cs_base.h"
#include "cs_halo.h"
#include "cs_interface.h"
#include "cs_math.h"
#include "cs_mesh.h"
#include "cs_mesh_quantities.h"
#include "cs_order.h"
#include "cs_parall.h"
#include "cs_prototypes.h"
#include "cs_search.h"
#include "cs_time_step.h"
#include "cs_timer_stats.h"
#include "cs_thermal_model.h"
#include "cs_field.h"
#include "cs_field_pointer.h"
#include "cs_prototypes.h"
#include "cs_lagr.h"
#include "cs_lagr_new.h"
#include "cs_lagr_particle.h"
#include "cs_lagr_stat.h"
#include "cs_lagr_geom.h"
/*----------------------------------------------------------------------------
* Header for the current file
*----------------------------------------------------------------------------*/
#include "cs_lagr_prototypes.h"
/*----------------------------------------------------------------------------*/
BEGIN_C_DECLS
/*! \cond DOXYGEN_SHOULD_SKIP_THIS */
/*============================================================================
* Global variables
*============================================================================*/
static cs_real_t _debm[4];
/*============================================================================
* Local (user defined) function definitions
*============================================================================*/
/*----------------------------------------------------------------------------
* Define inlet conditions based on experimental data for a given particle
*
* parameters:
* p_set <-> particle
* ip <-- particle id
*----------------------------------------------------------------------------*/
static void
_inlet2(cs_lagr_particle_set_t *p_set,
cs_lnum_t ip)
{
const int itmx = 8;
/* Data initializations with experimental measurements
--------------------------------------------------- */
unsigned char *particle = p_set->p_buffer + p_set->p_am->extents * ip;
const cs_real_t *part_coords = cs_lagr_particle_attr_const(particle,
p_set->p_am,
CS_LAGR_COORDS);
cs_real_t z = part_coords[2];
/* transverse coordinate */
cs_real_t zi[] = {0.e-3 , 1.e-3 , 1.5e-3, 2.0e-3, 2.5e-3,
3.0e-3, 3.5e-3, 4.0e-3, 4.5e-3, 5.0e-3};
/* vertical mean velocity of the particles */
cs_real_t ui[] = {5.544e0, 8.827e0, 9.068e0, 9.169e0, 8.923e0,
8.295e0, 7.151e0, 6.048e0, 4.785e0, 5.544e0};
/* transverse mean velocity of the particles */
cs_real_t wi[] = { 0.e0 , 0.179e0, 0.206e0, 0.221e0, 0.220e0,
0.223e0, 0.206e0, 0.190e0, 0.195e0, 0.504e0};
/* fluctuation of the vertical velocity of the particles */
cs_real_t uf[] = { 0.352e0, 0.352e0, 0.275e0, 0.252e0, 0.367e0,
0.516e0, 0.657e0, 0.872e0, 1.080e0, 0.792e0};
/* fluctuation of the transverse velocity of the particles */
cs_real_t wf[] = { 0.058e0, 0.058e0, 0.056e0, 0.056e0, 0.060e0,
0.063e0, 0.058e0, 0.072e0, 0.091e0, 0.232e0};
#if 0
/* shear-stress (currently not used) of the particle velocity */
cs_real_t uvi[] = {0.0017e0, 0.0017e0, 0.0016e0, 0.0027e0, 0.0077e0,
0.0146e0, 0.0206e0, 0.0447e0, 0.0752e0, 0.1145e0};
#endif
/* Interpolation
------------- */
int it = 0;
if (z > zi[0]) {
for (it = 0; it < itmx; it++) {
if (z >= zi[it] && z < zi[it+1])
break;
}
}
/* Calculation of particles velocity
--------------------------------- */
cs_real_t up = ui[it] +(z - zi[it]) * (ui[it+1] - ui[it])
/ (zi[it+1] - zi[it]);
/* The value of the mean transverse velocity is currently set to zero
* due to uncertainties on this variable */
cs_real_t wp;
if (false)
wp = wi[it] + (z - zi[it]) * (wi[it+1] - wi[it]) / (zi[it+1] - zi[it]);
else
wp = 0.0;
cs_real_t upp = uf[it] + (z - zi[it]) * (uf[it+1] - uf[it])
/ (zi[it+1] - zi[it]);
cs_real_t wpp = wf[it] + (z - zi[it]) * (wf[it+1] - wf[it])
/ (zi[it+1] - zi[it]);
/* Calculations of the instantaneous particle velocity */
cs_lnum_t two = 2;
cs_real_t vgauss[2];
CS_PROCF(normalen,NORMALEN) (&two,vgauss);
cs_real_t *part_vel
= cs_lagr_particle_attr(particle, p_set->p_am, CS_LAGR_VELOCITY);
part_vel[0] = up + vgauss[0] * upp;
part_vel[1] = 0.0;
part_vel[2] = wp + vgauss[1] * wpp;
}
/*! (DOXYGEN_SHOULD_SKIP_THIS) \endcond */
/*============================================================================
* User function definitions
*============================================================================*/
/*----------------------------------------------------------------------------*/
/*!
* \brief User definition of an external force field acting on the particles.
*
* It must be prescribed in every cell and be homogeneous to gravity (m/s^2)
* By default gravity and drag force are the only forces acting on the particles
* (the gravity components gx gy gz are assigned in the GUI or in usipsu)
*
* \param[in] dt_p time step (for the cell)
* \param[in] taup particle relaxation time
* \param[in] tlag relaxation time for the flow
* \param[in] piil term in the integration of the sde
* \param[in] bx characteristics of the turbulence
* \param[in] tsfext infos for the return coupling
* \param[in] vagaus Gaussian random variables
* \param[in] gradpr pressure gradient
* \param[in] gradvf gradient of the flow velocity
* \param[in,out] romp particle density
* \param[out] fextla user external force field (m/s^2)$
*/
/*----------------------------------------------------------------------------*/
void
cs_user_lagr_ef(cs_real_t dt_p,
const cs_real_t taup[],
const cs_real_3_t tlag[],
const cs_real_3_t piil[],
const cs_real_t bx[],
const cs_real_t tsfext[],
const cs_real_33_t vagaus[],
const cs_real_3_t gradpr[],
const cs_real_33_t gradvf[],
cs_real_t romp[],
cs_real_3_t fextla[])
{
cs_lagr_particle_set_t *p_set = cs_lagr_get_particle_set();
for (cs_lnum_t ip = 0; ip < p_set->n_particles; ip++){
fextla[ip][0] = 0;
fextla[ip][1] = 0;
fextla[ip][2] = 0;
}
}
/*----------------------------------------------------------------------------*/
/*!
* \brief User setting of particle inlet conditions for the particles (inlet
* and treatment for the other boundaries)
*
* This function is called after the initialization of the new particles in
* order to modify them according to new particle profiles (injection
* profiles, position of the injection point, statistical weights,
* correction of the diameter if the standard-deviation option is activated).
*
* \param[in] time_id time step indicator for fields
* 0: use fields at current time step
* 1: use fields at previous time step
* \param[in] injfac array of injection face id for every particles
* \param[in] local_userdata local_userdata pointer to zone/cluster specific
* boundary conditions (number of injected
* particles, velocity profile...)
*/
/*----------------------------------------------------------------------------*/
void
cs_user_lagr_in(int time_id,
int *injfac,
cs_lagr_zone_class_data_t *local_userdata,
cs_real_t vislen[] )
{
const int ntcabs = cs_glob_time_step->nt_cur;
cs_lagr_bdy_condition_t *lagr_bdy_conditions = cs_lagr_get_bdy_conditions();
cs_lagr_particle_set_t *p_set = cs_lagr_get_particle_set();
const cs_lagr_attribute_map_t *p_am = p_set->p_am;
if (p_set->n_part_new == 0)
return;
/* Modifications occur after all the initializations related to
the particle injection, but before the treatment of the continuous
injection: it is thus possible to impose an injection profile with
the continous-injection option. */
/* reinitialization of the counter of the new particles */
cs_lnum_t npt = p_set->n_particles;
/* for each boundary zone */
for (cs_lnum_t ii = 0; ii < lagr_bdy_conditions->n_b_zones; ii++) {
cs_lnum_t izone = lagr_bdy_conditions->b_zone_id[ii];
/* for each class */
for (cs_lnum_t iclas = 0;
iclas < lagr_bdy_conditions->b_zone_classes[izone];
iclas++) {
cs_lagr_zone_class_data_t *userdata
= &(local_userdata[iclas * cs_glob_lagr_nzone_max + izone]);
/* if new particles must enter the domain: */
if (ntcabs % userdata->injection_frequency == 0) {
for (cs_lnum_t ip = npt; ip < npt + userdata->nb_part; ip++) {
cs_lnum_t face_id = injfac[ip]; /* id of injection face */
_inlet2(p_set, ip);
}
npt += userdata->nb_part;
}
}
}
/*
* Trick to average the statistics at iteration nstist
* starting from an unsteady two-coupling calculation
* */
if (cs_glob_time_step->nt_cur > cs_glob_lagr_stat_options->nstist) {
cs_glob_lagr_source_terms->nstits = cs_glob_lagr_stat_options->nstist;
cs_glob_lagr_time_scheme->isttio = 1;
}
/* Simulation of the instantaneous turbulent fluid flow velocities seen
by the solid particles along their trajectories
-------------------------------------------------------------------- */
/* In the previous operations, the particle data has been set with the
* components of the instantaneous velocity (fluctuation + mean value) seen
* by the particles.
*
* When the velocity of the flow is modified as above, most of the time
* the user knows only the mean value. In some flow configurations and some
* injection conditions, it may be necessary to reconstruct the fluctuating part.
* That is why the following function may be called.
* Caution:
* - this turbulent component must be reconstructed only on the modified
* velocities of the flow seen.
* - the reconstruction is must be adapted to the case. */
if (false) {
cs_lnum_t npar1 = p_set->n_particles;
cs_lnum_t npar2 = p_set->n_particles + p_set->n_part_new;
cs_lagr_new_particle_init(npar1, npar2, time_id, vislen);
}
}
/*----------------------------------------------------------------------------*/
/*!
* \brief Prescribe some attributes for newly injected particles.
*
* This function is called at different points, at which different attributes
* may be modified.
*
* \param[inout] particle particle structure
* \param[in] p_am particle attributes map
* \param[in] face_id id of particle injection face
* \param[in] attr_id id of variable modifiable by this call. called for
CS_LAGR_VELOCITY, CS_LAGR_DIAMETER,
CS_LAGR_TEMPERATURE, CS_LAGR_STAT_WEIGHT
*/
/*----------------------------------------------------------------------------*/
void
cs_user_lagr_new_p_attr(unsigned char *particle,
const cs_lagr_attribute_map_t *p_am,
cs_lnum_t face_id,
cs_lagr_attribute_t attr_id)
{
const cs_real_t pis6 = cs_math_pi / 6.0;
/* Velocity profile */
if (attr_id == CS_LAGR_VELOCITY) {
cs_real_t *part_vel = cs_lagr_particle_attr(particle, p_am, CS_LAGR_VELOCITY);
part_vel[0] = 1.0;
part_vel[1] = 0.0;
part_vel[2] = 0.0;
}
/* Diameter profile */
if (attr_id == CS_LAGR_DIAMETER)
cs_lagr_particle_set_real(particle, p_am, CS_LAGR_DIAMETER, 5e-05);
/* Temperature profile */
if (attr_id == CS_LAGR_TEMPERATURE)
cs_lagr_particle_set_real(particle, p_am, CS_LAGR_TEMPERATURE, 20.0);
/* Statistical weight profile */
if (attr_id == CS_LAGR_STAT_WEIGHT)
cs_lagr_particle_set_real(particle, p_am, CS_LAGR_STAT_WEIGHT, 0.01);
}
/*----------------------------------------------------------------------------*/
/*!
* \brief Impose the motion of a particle falgged CS_LAGR_PART_IMPOSED_MOTION.
*
* User-defined modifications on the particle position and its
* velocity.
* \param[in] coords old particle coordinates
* \param[in] dt time step (per particle)
* \param[out] disp particle dispacement
*/
/*----------------------------------------------------------------------------*/
void
cs_user_lagr_imposed_motion(const cs_real_3_t coords,
const cs_real_t dt,
cs_real_3_t disp)
{
/* Angular velocity */
cs_real_t omega = 1.0;
/* Here we impose the particle to move arround a cylinder with
* the axe is (*, 0, 1) */
cs_real_t rcost = (coords[1] - 0.0);
cs_real_t rsint = (coords[2] - 1.0);
/* Imposed displacement */
disp[0] = 0.;
disp[1] = rcost * (cos(omega*dt) - 1.0 ) - rsint * sin(omega*dt);
disp[2] = rsint * (cos(omega*dt) - 1.0 ) + rcost * sin(omega*dt);
}
/*----------------------------------------------------------------------------*/
/*!
* \brief User function (non-mandatory intervention)
*
* User-defined modifications on the variables at the end of the
* Lagrangian time step and calculation of user-defined
* additional statistics on the particles.
*/
/*----------------------------------------------------------------------------*/
void
cs_user_lagr_extra_operations(const cs_real_t dt[])
{
cs_lagr_particle_set_t *p_set = cs_lagr_get_particle_set();
const cs_lagr_attribute_map_t *p_am = p_set->p_am;
cs_lnum_t nxlist = 100;
const cs_lnum_t nfac = cs_glob_mesh->n_i_faces;
const cs_lnum_t n_cells_ext = cs_glob_mesh->n_cells_with_ghosts;
const cs_real_3_t *ifacel = cs_glob_mesh->i_face_cells;
const cs_lnum_t n_cells = cs_glob_mesh->n_cells;
const cs_lnum_t n_vertices = cs_glob_mesh->n_vertices;
const cs_real_t *cdgfac = cs_glob_mesh_quantities->i_face_cog;
const cs_real_t *cell_cen = cs_glob_mesh_quantities->cell_cen;
const cs_real_t *pond = cs_glob_mesh_quantities->weight;
/* Example: computation of the particle mass flow rate on 4 planes
--------------------------------------------------------------- */
if (false) {
cs_real_t zz[4] = {0.1e0, 0.15e0, 0.20e0, 0.25e0};
/* If we are in an unsteady case, or if the beginning of the steady stats
* is not reached yet, all statistics are reset to zero at each time
step before entering this function.*/
if( cs_glob_lagr_time_scheme->isttio == 0
|| cs_glob_time_step->nt_cur <= cs_glob_lagr_stat_options->nstist) {
for (cs_lnum_t iplan = 0; iplan < 4; iplan++)
_debm[iplan] = 0.0;
}
for (cs_lnum_t iplan = 0; iplan < 4; iplan++) {
for (cs_lnum_t npt = 0; p_set->n_particles; npt++) {
unsigned char *part = p_set->p_buffer + p_am->extents * npt;
cs_lnum_t iel = cs_lagr_particle_get_cell_id(part, p_am);
if( iel >= 0 ) {
const cs_real_t *part_coords
= cs_lagr_particle_attr_const(part, p_am, CS_LAGR_COORDS);
const cs_real_t *prev_part_coords
= cs_lagr_particle_attr_n_const(part, p_am, 1, CS_LAGR_COORDS);
if( part_coords[0] > zz[iplan]
&& prev_part_coords[0] <= zz[iplan])
_debm[iplan] += cs_lagr_particle_get_real(part, p_am,
CS_LAGR_STAT_WEIGHT)
* cs_lagr_particle_get_real(part, p_am, CS_LAGR_MASS);
}
}
}
cs_real_t stat_age = cs_lagr_stat_get_age();
for (cs_lnum_t iplan = 0; iplan < 4; iplan++)
bft_printf(" Debit massique particulaire en Z(%d) : %E14.5)",
iplan,
_debm[iplan]/stat_age);
}
}
/*----------------------------------------------------------------------------*/
/*!
* \brief Modification of the calculation of the particle relaxation time
* with respect to the chosen formulation for the drag coefficient
*
* This function is called in a loop on the particles, so be careful
* to avoid too costly operations.
*
* m Cp
* p p
* Tau = ---------------
* c 2
* PI d h
* p e
*
* Tau : Thermal relaxation time (value to be computed)
* c
*
* m : Particle mass
* p
*
* Cp : Particle specific heat
* p
*
* d : Particle diameter
* p
*
* h : Coefficient of thermal exchange
* e
*
* he coefficient of thermal exchange is calculated from a Nusselt number,
* itself evaluated by a correlation (Ranz-Marshall by default)
*
* h d
* e p
* Nu = -------- = 2 + 0.55 Re **(0.5) Prt**(0.33)
* Lambda p
*
* Lambda : Thermal conductivity of the carrier field
*
* Re : Particle Reynolds number
* p
*
* Prt : Prandtl number
*
* \param[in] id_p particle id
* \param[in] re_p particle Reynolds number
* \param[in] uvwr relative velocity of the particle
* (flow-seen velocity - part. velocity)
* \param[in] rho_f fluid density at particle position
* \param[in] rho_p particle density
* \param[in] nu_f kinematic viscosity of the fluid at particle position
* \param[in] cp_f specific heat of the fluid at particle position
* \param[in] k_f diffusion coefficient of the fluid at particle position
* \param[out] taup thermal relaxation time
* \param[in] dt time step (per cell)
*/
/*----------------------------------------------------------------------------*/
void
cs_user_lagr_rt(cs_lnum_t id_p,
cs_real_t re_p,
cs_real_t uvwr,
cs_real_t rho_f,
cs_real_t rho_p,
cs_real_t nu_f,
cs_real_t taup[],
const cs_real_t dt[])
{
/* Particles management */
cs_lagr_particle_set_t *p_set = cs_lagr_get_particle_set();
const cs_lagr_attribute_map_t *p_am = p_set->p_am;
unsigned char *particle = p_set->p_buffer + p_am->extents * id_p;
cs_real_t p_diam = cs_lagr_particle_get_real(particle, p_am, CS_LAGR_DIAMETER);
/*===============================================================================
* Relaxation time with the standard (Wen-Yu) formulation of the drag coefficient
*===============================================================================*/
/* This example gives the standard relaxation time as an indication:*/
cs_real_t fdr;
cs_real_t cd1 = 0.15;
cs_real_t cd2 = 0.687;
if (re_p <= 1000)
fdr = 18.0 * nu_f * (1.0 + cd1 * pow(re_p, cd2)) / (p_diam * p_diam);
else
fdr = (0.44 * 3.0 / 4.0) * uvwr / p_diam;
taup[id_p] = rho_p / rho_f / fdr;
/*===============================================================================
* Computation of the relaxation time with the drag coefficient of
* S.A. Morsi and A.J. Alexander, J. of Fluid Mech., Vol.55, pp 193-208 (1972)
*===============================================================================*/
cs_real_t rec1 = 0.1;
cs_real_t rec2 = 1.0;
cs_real_t rec3 = 10.0;
cs_real_t rec4 = 200.0;
cs_real_t dd2 = p_diam * p_diam;
if (re_p <= rec1)
fdr = 18.0 * nu_f / dd2;
else if (re_p <= rec2)
fdr = 3.0/4.0 * nu_f / dd2 * (22.73 + 0.0903 / re_p + 3.69 * re_p);
else if (re_p <= rec3)
fdr = 3.0/4.0 * nu_f / dd2 * (29.1667 - 3.8889 / re_p + 1.222 * re_p);
else if (re_p <=rec4)
fdr = 18.0 * nu_f / dd2 *(1.0 + 0.15 * pow(re_p, 0.687));
else
fdr = (0.44 * 3.0 / 4.0) * uvwr / p_diam;
taup[id_p] = rho_p / rho_f / fdr;
}
/*----------------------------------------------------------------------------*/
/*!
* \brief Modification of the computation of the thermal relaxation time
* of the particles with respect to the chosen formulation of
* the Nusselt number.
*
* This function is called in a loop on the particles, so be careful
* to avoid too costly operations.
*
* \param[in] id_p particle id
* \param[in] re_p particle Reynolds number
* \param[in] uvwr relative velocity of the particle
* (flow-seen velocity - part. velocity)
* \param[in] rho_f fluid density at particle position
* \param[in] rho_p particle density
* \param[in] nu_f kinematic viscosity of the fluid at particle position
* \param[in] cp_f specific heat of the fluid at particle position
* \param[in] k_f diffusion coefficient of the fluid at particle position
* \param[out] tauc thermal relaxation time
* \param[in] dt time step (per cell)
*/
/*-------------------------------------------------------------------------------*/
void
cs_user_lagr_rt_t(cs_lnum_t id_p,
cs_real_t re_p,
cs_real_t uvwr,
cs_real_t rho_f,
cs_real_t rho_p,
cs_real_t nu_f,
cs_real_t cp_f,
cs_real_t k_f,
cs_real_t tauc[],
const cs_real_t dt[])
{
/* 1. Initializations: Particles management */
cs_lagr_particle_set_t *p_set = cs_lagr_get_particle_set();
const cs_lagr_attribute_map_t *p_am = p_set->p_am;
unsigned char *particle = p_set->p_buffer + p_am->extents * id_p;
/* 2. Standard thermal relaxation time */
/* This example gives the standard thermal relaxation time
* as an indication.*/
cs_real_t prt = nu_f / k_f;
cs_real_t fnus = 2.0 + 0.55 * sqrt(re_p) * pow(prt, 1./3.);
cs_real_t diam = cs_lagr_particle_get_real(particle, p_am, CS_LAGR_DIAMETER);
cs_real_t cp_p = cs_lagr_particle_get_real(particle, p_am, CS_LAGR_CP);
tauc[id_p]= diam * diam * rho_p * cp_p / ( fnus * 6.0 * rho_f * cp_f * k_f);
}
/*----------------------------------------------------------------------------*/
/*!
* \brief User integration of the SDE for the user-defined variables.
*
* The variables are constant by default. The SDE must be of the form:
*
* \f[
* \frac{dT}{dt}=\frac{T - PIP}{Tca}
* \f]
*
* T: particle attribute representing the variable
* Tca: characteristic time for the sde
* to be prescribed in the array auxl1
* PIP: coefficient of the SDE (pseudo RHS)
* to be prescribed in the array auxl2.
* If the chosen scheme is first order (nordre=1) then, at the first
* and only call pip is expressed as a function of the quantities of
* the previous time step (contained in the particle data).
* If the chosen scheme is second order (nordre=2)
* then, at the first call (nor=1) pip is expressed as a function of
* the quantities of the previous time step, and at the second passage
* (nor=2) pip is expressed as a function of the quantities of the
* current time step.
*
* \param[in] dt time step (per cell)
* \param[in] taup particle relaxation time
* \param[in] tlag relaxation time for the flow
* \param[in] tempct characteristic thermal time and implicit source
* term of return coupling
*/
/*----------------------------------------------------------------------------*/
void
cs_user_lagr_sde(const cs_real_t dt[],
cs_real_t taup[],
cs_real_3_t tlag[],
cs_real_t tempct[])
{
/* Initializations
--------------- */
cs_lagr_particle_set_t *p_set = cs_lagr_get_particle_set();
const cs_lagr_attribute_map_t *p_am = p_set->p_am;
cs_real_t *tcarac, *pip;
BFT_MALLOC(tcarac, p_set->n_particles, cs_real_t);
BFT_MALLOC(pip , p_set->n_particles, cs_real_t);
/* Characteristic time of the current SDE
-------------------------------------- */
/* Loop on the additional variables */
for (int iiii = 0;
iiii < cs_glob_lagr_model->n_user_variables;
iiii++) {
for (cs_lnum_t npt = 0; npt < p_set->n_particles; npt++) {
unsigned char *part = p_set->p_buffer + p_am->extents * npt;
cs_lnum_t iel = cs_lagr_particle_get_cell_id(part, p_am);
cs_real_t *usr_var
= cs_lagr_particle_attr_n(part, p_am, 0, CS_LAGR_USER);
cs_real_t *prev_usr_var
= cs_lagr_particle_attr_n(part, p_am, 1, CS_LAGR_USER);
if (iel >= 0) {
/* Characteristic time tca of the differential equation,
This example must be adapted to the case */
tcarac[npt] = 1.0;
/* Prediction at the first substep;
This example must be adapted to the case */
if (cs_glob_lagr_time_step->nor == 1)
pip[npt] = prev_usr_var[iiii];
/* Correction at the second substep;
This example must be adapted to the case */
else
pip[npt] = usr_var[iiii];
}
}
/* Integration of the variable ipl
------------------------------- */
cs_lagr_sde_attr(CS_LAGR_USER, tcarac, pip);
}
BFT_FREE(tcarac);
BFT_FREE(pip);
}
/*----------------------------------------------------------------------------*/
END_C_DECLS
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