9.2
general documentation
For velocity components equation (Navier-Stokes)

Additional right-hand side source terms for velocity components equation (Navier-Stokes)

Local variables and initialization

/* field structure */
const cs_field_t *f = cs_field(f_id);
/* mesh quantities */
const cs_lnum_t n_cells = domain->mesh->n_cells;
const cs_real_t *cell_f_vol = domain->mesh_quantities->cell_vol;
/* density */
const auto cpro_rom = CS_F_(rho)->get_val_s();
cs_field_t
Field descriptor.
Definition: cs_field.h:275
cs_real_t
double cs_real_t
Floating-point value.
Definition: cs_defs.h:332
cs_lnum_t
int cs_lnum_t
local mesh entity id
Definition: cs_defs.h:325
cs_field
cs_field_t * cs_field(int id)
Return a pointer to a field based on its id. This function requires that a field of the given id is d...
Definition: cs_field.cpp:4295
rho
@ rho
Definition: cs_field_pointer.h:96
CS_F_
#define CS_F_(e)
Macro used to return a field pointer by its enumerated value.
Definition: cs_field_pointer.h:47

Example

Example of arbitrary source term for component $\vect{u}$:

$ \vect{S} = \tens{A} \cdot \vect{u} + \vect{B} $ appearing in the equation under the form:

$ \rho \dfrac{d\vect{u}}{dt} = \vect{S} \: (+ \text{standard Navier-Stokes terms})$

In the following example:

\[ \tens{A} = -\rho \cdot \tens{CKP} \]

\[ \vect{B} = \vect{XMMT} \]

with:

  • CKP = 1.0 (in $ s^{-1}$) (return term on velocity)
  • MMT = 100.0 (in $kg \cdot m^{-2} \cdot s^{-2}$) (momentum production by volume and time unit)

which yields:

  • st_imp[i][0][0] = volume[i] * A = - volume[i]*(rho*CKP)
  • st_exp[i][0] = volume[i] * B = volume[i]*(XMMT)

Body

if (f == CS_F_(vel)) { /* velocity */
/* cast to 3D vectors for readability */
cs_real_3_t *_st_exp = (cs_real_3_t *)st_exp;
cs_real_33_t *_st_imp = (cs_real_33_t *)st_imp;
/* Density */
const cs_real_t ckp = 10.0;
const cs_real_t mmt = 100.0;
for (cs_lnum_t i = 0; i < n_cells; i++) {
_st_imp[i][0][0] = - cell_f_vol[i] * cpro_rom[i] * ckp;
_st_exp[i][0] = cell_f_vol[i] * mmt;
}
}
cs_real_3_t
cs_real_t cs_real_3_t[3]
vector of 3 floating-point values
Definition: cs_defs.h:349
cs_real_33_t
cs_real_t cs_real_33_t[3][3]
3x3 matrix of floating-point values
Definition: cs_defs.h:358
vel
@ vel
Definition: cs_field_pointer.h:66

Example of a boussinesq momentum source term

Example to add Boussinesq source to the z component of $\vect{u}$:

Body

if (f == CS_F_(vel) && CS_F_(t) != nullptr) { /* velocity and temperature */
/* expansion coefficient and reference density */
const cs_real_t beta = 1.;
const cs_real_t ro0 = cs_glob_fluid_properties->ro0;
const cs_real_t t0 = cs_glob_fluid_properties->t0;
/* get temperature */
const auto cvar_temperature = CS_F_(t)->get_val_s();
/* source term (in z direction here) */
cs_real_3_t *_st_exp = (cs_real_3_t *)st_exp;
for (cs_lnum_t i = 0; i < n_cells; i++) {
_st_exp[i][2] = cell_f_vol[i] * ro0 * beta * (cvar_temperature[i]-t0);
}
}
t
@ t
Definition: cs_field_pointer.h:91
cs_glob_fluid_properties
const cs_fluid_properties_t * cs_glob_fluid_properties
Definition: cs_physical_constants.cpp:462
cstphy::t0
real(c_double), pointer, save t0
reference temperature.
Definition: cstphy.f90:68
cs_fluid_properties_t::ro0
double ro0
Definition: cs_physical_constants.h:74
cs_fluid_properties_t::t0
double t0
Definition: cs_physical_constants.h:84