2.3 Model-Specific DEFINE Macros

The DEFINE macros presented in this section are used to set parameters for a particular model in ANSYS FLUENT. Table  2.3-Table  2.3.5 provides a quick reference guide to the DEFINE macros, the functions they are used to define, and the dialog boxes where they are activated in ANSYS FLUENT. Definitions of each DEFINE macro are listed in udf.h. For your convenience, they are listed in Appendix  B.

Table 2.3.1: Quick Reference Guide for Model-Specific DEFINE Functions

Function	DEFINE Macro	Dialog Box Activated In
mixing constant	DEFINE_CPHI	User-Defined Function Hooks
homogeneous net mass reaction rate for all species, integrated over a time step	DEFINE_CHEM_STEP	User-Defined Function Hooks
species mass or UDS diffusivity	DEFINE_DIFFUSIVITY	Create/Edit Materials
diffusive reflectivity for discrete ordinates (DO) model	DEFINE_DOM_DIFFUSE_ REFLECTIVITY	User-Defined Function Hooks
source for DO model	DEFINE_DOM_SOURCE	User-Defined Function Hooks
specular reflectivity for DO model	DEFINE_DOM_SPECULAR_ REFLECTIVITY	User-Defined Function Hooks
emissivity weighting factor for the RTE of the non-gray DO model	DEFINE_EMISSIVITY_ WEIGHTING_FACTOR	User-Defined Function Hooks
gray band absorption coefficient for DO model	DEFINE_GRAY_BAND_ ABS_COEFF	Create/Edit Materials
wall heat flux	DEFINE_HEAT_FLUX	User-Defined Function Hooks
ignition time source	DEFINE_IGNITE_SOURCE	User-Defined Function Hooks
homogeneous net mass reaction rate for all species	DEFINE_NET_ REACTION_RATE	User-Defined Function Hooks

Table 2.3.2: Quick Reference Guide for Model-Specific DEFINE Functions-Continued

Function	DEFINE Macro	Dialog Box Activated In
NOx formation rates (for Thermal NOx, Prompt NOx, Fuel NOx, and N $_2$O Pathways) and upper limit for temperature PDF	DEFINE_NOX_RATE	NOx Model
particle surface reaction rate	DEFINE_PR_RATE	User-Defined Function Hooks
Prandtl numbers	DEFINE_PRANDTL	Viscous Model
species mass fraction	DEFINE_PROFILE	boundary condition (e.g., Velocity Inlet)
velocity at a boundary	DEFINE_PROFILE	boundary condition
pressure at a boundary	DEFINE_PROFILE	boundary condition
temperature at a boundary	DEFINE_PROFILE	boundary condition
mass flux at a boundary	DEFINE_PROFILE	boundary condition
target mass flow rate for pressure outlet	DEFINE_PROFILE	Pressure Outlet
turbulence kinetic energy	DEFINE_PROFILE	boundary condition (e.g., Velocity Inlet)
turbulence dissipation rate	DEFINE_PROFILE	boundary condition
specific dissipation rate	DEFINE_PROFILE	boundary condition
porosity	DEFINE_PROFILE	boundary condition
viscous resistance	DEFINE_PROFILE	boundary condition
inertial resistance	DEFINE_PROFILE	boundary condition
porous resistance direction vector	DEFINE_PROFILE	boundary condition
user-defined scalar boundary value	DEFINE_PROFILE	boundary condition
internal emissivity	DEFINE_PROFILE	boundary condition

Table 2.3.3: Quick Reference Guide for Model-Specific DEFINE Functions-Continued

Function	DEFINE Macro	Dialog Box Activated In
wall thermal conditions (heat flux, heat generation rate, temperature, heat transfer coefficient, external emissivity, external radiation and free stream temperature)	DEFINE_PROFILE	boundary condition
wall radiation (internal emissivity, irradiation)	DEFINE_PROFILE	boundary condition
wall momentum (shear stress x,y,z components swirl component, moving wall velocity components, roughness height, roughness constant)	DEFINE_PROFILE	boundary condition
wall species mass fractions	DEFINE_PROFILE	boundary condition
wall user-defined scalar boundary value	DEFINE_PROFILE	boundary condition
wall discrete phase boundary value	DEFINE_PROFILE	boundary condition
density (as function of temperature)	DEFINE_PROPERTY	Create/Edit Materials
density (as function of pressure for compressible liquids)	DEFINE_PROPERTY	Create/Edit Materials
viscosity	DEFINE_PROPERTY	Create/Edit Materials
mass diffusivity	DEFINE_PROPERTY	Create/Edit Materials
thermal conductivity	DEFINE_PROPERTY	Create/Edit Materials
thermal diffusion coefficient	DEFINE_PROPERTY	Create/Edit Materials

Table 2.3.4: Quick Reference Guide for Model-Specific DEFINE Functions-Continued

Function	DEFINE Macro	Dialog Box Activated In
absorption coefficient	DEFINE_PROPERTY	Create/Edit Materials
scattering coefficient	DEFINE_PROPERTY	Create/Edit Materials
laminar flow speed	DEFINE_PROPERTY	Create/Edit Materials
rate of strain	DEFINE_PROPERTY	Create/Edit Materials
speed of sound function	DEFINE_PROPERTY	Create/Edit Materials
user-defined mixing law for mixture materials (density viscosity, thermal conductivity)	DEFINE_PROPERTY	Create/Edit Materials
scattering phase function	DEFINE_SCAT_PHASE_FUNC	Create/Edit Materials
solar intensity	DEFINE_SOLAR_INTENSITY	Radiation Model
mass source	DEFINE_SOURCE	cell zone condition
momentum source	DEFINE_SOURCE	cell zone condition
energy source	DEFINE_SOURCE	cell zone condition
turbulence kinetic energy source	DEFINE_SOURCE	cell zone condition
turbulence dissipation rate source	DEFINE_SOURCE	cell zone condition
species mass fraction source	DEFINE_SOURCE	cell zone condition
user-defined scalar source	DEFINE_SOURCE	cell zone condition
P1 radiation model source	DEFINE_SOURCE	cell zone condition
SOx formation rate and upper limit for temperature PDF	DEFINE_SOX_RATE	SOx Model
specific heat and sensible enthalpy	DEFINE_SPECIFIC_HEAT	Create/Edit Materials
surface reaction rate	DEFINE_SR_RATE	User-Defined Function Hooks
transition correlation numbers	DEFINE_TRANS	Viscous Model
turbulent premixed source	DEFINE_TURB_PREMIX_ SOURCE	User-Defined Function Hooks
turbulent Schmidt number	DEFINE_TURB_SCHMIDT	Viscous Model
turbulent viscosity	DEFINE_TURBULENT_ VISCOSITY	Viscous Model
volume reaction rate	DEFINE_VR_RATE	User-Defined Function Hooks
wall function	DEFINE_WALL_FUNCTIONS	Viscous Model

Table 2.3.5: Quick Reference Guide for Model-Specific DEFINE Functions MULTIPHASE ONLY

Function	DEFINE Macro	Dialog Box Activated In
volume fraction (all multiphase models)	DEFINE_PROFILE	boundary condition
contact angle (VOF)	DEFINE_PROFILE	Wall boundary condition
heat transfer coefficient (Eulerian)	DEFINE_PROPERTY	Phase Interaction
surface tension coefficient (VOF)	DEFINE_PROPERTY	Phase Interaction
cavitation surface tension coefficient (Mixture)	DEFINE_PROPERTY	Phase Interaction
cavitation vaporization pressure (Mixture)	DEFINE_PROPERTY	Phase Interaction
particle or droplet diameter (Mixture)	DEFINE_PROPERTY	Create/Edit Materials
diameter (Eulerian, Mixture)	DEFINE_PROPERTY	Secondary Phase
solids pressure (Eulerian, Mixture)	DEFINE_PROPERTY	Secondary Phase
radial distribution (Eulerian, Mixture)	DEFINE_PROPERTY	Secondary Phase
elasticity modulus (Eulerian, Mixture)	DEFINE_PROPERTY	Secondary Phase
viscosity (Eulerian, Mixture)	DEFINE_PROPERTY	Secondary Phase
temperature (Eulerian, Mixture)	DEFINE_PROPERTY	Secondary Phase
bulk viscosity (Eulerian)	DEFINE_PROPERTY	Secondary Phase
frictional viscosity (Eulerian)	DEFINE_PROPERTY	Secondary Phase
frictional pressure (Eulerian)	DEFINE_PROPERTY	Secondary Phase
frictional modulus (Eulerian)	DEFINE_PROPERTY	Secondary Phase
granular viscosity (Eulerian)	DEFINE_PROPERTY	Secondary Phase
granular bulk viscosity (Eulerian)	DEFINE_PROPERTY	Secondary Phase
granular conductivity (Eulerian)	DEFINE_PROPERTY	Secondary Phase
temperature source (Eulerian, Mixture)	DEFINE_SOURCE	boundary condition