Under the General section, retain the following setting:

Under the Type section, retain the following settings:

Under the Model section, retain the following settings:

LWC [kg/m3]: Reference liquid water content (LWC) which can be used either for collection efficiency normalization or for injection properties.

Droplet Diameter [microns]: Median volume diameter (MVD) of a spherical particle for a given distribution which is used only when Edit is used to create injections.

Water Density [kg/m3]: Density of water droplets.

Monodispersed.

Langmuir B to E.

Custom.

Spherical: No additional changes are needed.

Nonspherical: Specify the Shape Factor.

Stokes – Cunningham: Specify the Cunningham Correction.

User-Defined: Click the Refresh button to update the list of available user-defined functions loaded in the Fluent case file. The user-defined functions listed should be generated using the DEFINE_DPM_DRAG macro (Discrete Phase Model (DPM) DEFINE Macros).

Ice Crystal Content [kg/m3]: Reference ice crystal content (ICC) which can be used either for collection efficiency normalization or for injection properties.

Crystal Diameter [microns]: Median volume diameter (MVD) of a spherical particle for a given distribution which is used only when  Setup → Particles → Injection Type → Edit is used to create injections.

Crystal Density [kg/m3]: Density of crystals.

Spherical: No additional changes are needed.

Nonspherical: Specify the Shape Factor.

User-Defined: Click the Refresh button to update the list of available user-defined functions loaded in the Fluent case file. The user-defined functions listed should be generated using the DEFINE_DPM_DRAG macro (Discrete Phase Model (DPM) DEFINE Macros).

From Ref. Conditions: If enabled using the discrete particles solver, only the reference LWC and temperature are used.

Droplet LWC [kg/m3]: If From Ref. Conditions is unchecked, set the water droplet concentration.

Droplet Temperature [K]: Specify the temperature of the cloud of water droplets at the inlet.

Use for Injection: Enables the creation of a new injection based on the boundary condition surface.

Droplet X,Y,Z Velocity [m/s]: Sets the velocity components of the water droplet cloud.

From Ref. Conditions: If enabled using the discrete particles solver, only the reference ICC and temperature are used.

Crystal ICC [kg/m3]: If From Ref. Conditions is unchecked, set the ice content concentration.

Crystal Temperature [K]: Specify the temperature of the cloud of water droplets at the inlet.

Crystal Melt Fraction: A value between 0 and 1 can be assigned if the crystal temperature is equal to 273.15K. For a crystal temperature lower or greater than 273.15K, the melt fraction is automatically set to 0 and 1, respectively.

Crystal X,Y,Z Velocity [m/s]: Sets the velocity components of the ice crystal cloud.

Use for Injection: Enables the creation of a new injection based on the boundary condition surface.

Number of Streams: Numerical parameters, defines the number of points located at the surface releasing a particle stream.

Vapor Condition Species Mode: Choose between Relative Humidity, Vapor Concentration or Case Settings for the vapor inlet boundary condition specification.

Relative Humidity [%]: Set the inlet relative humidity value.

Vapor Concentration [kg/m3]: Set the inlet vapor concentration value.

Collection: The particles are collected locally when hitting the wall ending the particle trajectory. The particle fate is listed as Trap in the summary.

Rebound: The particles are reflected when hitting the wall. The rebound velocity vector is in the same plane as the incident velocity vector and the wall normal vector. The components are computed using normal and tangential rebound coefficients. The Normal and Tangential rebound coefficients are defined as polynomes of the impact angle θ (in degree):

Where is the polynomial coefficient in direction to be defined.

Mundo: Mundo formulation is used to evaluate the local collection of particles. When a particle stream impacts the wall, it will either splash or be reflected depending on the impact and particle properties. When the particle stream splashes, part of the mass is collected at the wall and the remaining mass is reinjected using rebound coefficients and a diameter computed by the Mundo model (Mundo Model).

User-Defined: Click the Refresh button to update the list of available user-defined functions loaded in the Fluent case file. The user-defined functions listed should be generated using the DEFINE_DPM_BC macro (Discrete Phase Model (DPM) DEFINE Macros). The function should update the particle stream properties including velocity components, droplet diameter and flow rate. The change in flow rate after impingement will be automatically collected locally at the wall. Some variables might need an update of the value entering the cell and of the initial value. Table 39.3: List of Variables to Update in DEFINE_DPM_BC Macro provides the list of variables to update in the UDF.

Example:

This example shows the usage of DEFINE_DPM_BC for the fragmentation of crystals when they hit the walls. The function assumes that the mass of a single particle after the collision is 30% of the impinging particle mass (fragmentation_coeff = 0.3) and the flow rate is equal to 50% (sticking_coeff = 0.5) of the incoming flow rate (which means that 50% of the incoming flow rate is collected at the wall). For the crystals reinjected in the airflow, the function assumes an ideal reflection for the normal component of the velocity (nor_coeff = 1.) while the tangential component is damped (tan_coeff = 0.3). The function returns PATH_ACTIVE for the crystals reinjected in the airflow while it stops all other particles returning PATH_ABORT.

#include "udf.h"
#define PART_MIN_DIAMETER 1.e-6
 
 DEFINE_DPM_BC(bc_sticking_fragmentation,tp,t,f,f_normal,dim)
 {
    real vn=0.;
    real nor_coeff = 1.;
    real tan_coeff = 0.3;
	real fragmentation_coeff = 0.3; /* particle diameter ratio after and before wall impingement*/
	real sticking_coeff = 0.5; /* mass fraction accumulated at the wall */
    int i;
	
    /* DPM Types used in Fluent Icing - 3D only */
    if(TP_TYPE(tp) == DPM_TYPE_INERT || TP_TYPE(tp) == DPM_TYPE_DROPLET)
      {
       /* calculate the normal component, rescale its magnitude by
         the coefficient of restitution and subtract the change */

       /* Compute normal velocity. */
        for(i=0; i<dim; i++)
          vn += TP_VEL(tp)[i]*f_normal[i];

       /* Subtract off normal velocity. */
        for(i=0; i<dim; i++)
            TP_VEL(tp)[i] -= vn*f_normal[i];

       /* Apply tangential coefficient of restitution. */
        for(i=0; i<dim; i++)
          TP_VEL(tp)[i] *= tan_coeff;

       /* Add reflected normal velocity. */
        for(i=0; i<dim; i++)
          TP_VEL(tp)[i] -= nor_coeff*vn*f_normal[i];

        /* update individual particle mass TP_MASS
		   update TP_INIT_MASS too to evaluate the number of particles */
        TP_MASS(tp)*=fragmentation_coeff;
        TP_INIT_MASS(tp)=TP_MASS(tp);

		/* compute new individual particle diameter */
        TP_DIAM(tp)=pow(6.*TP_MASS(tp)/TP_RHO(tp)/M_PI,1./3.);
		
		/* update stream flow rate */
        TP_FLOW_RATE(tp)*= (1. - sticking_coeff);
		
         /* Update particle state variables at cell entry */
        for(i=0; i<dim; i++)
          TP_VEL0(tp)[i] = TP_VEL(tp)[i];
		TP_MASS0(tp)=TP_MASS(tp);
        TP_DIAM0(tp)=TP_DIAM(tp);
	
		if (TP_DIAM(tp)>PART_MIN_DIAMETER)
         return PATH_ACTIVE;
		else
         return PATH_ABORT;
	   }
  return PATH_ABORT;
 }

Condition: If Mixing Plane is enabled, choose between a regular Escape condition for particles, or a Mixing condition which is an escape condition coupled with data collection for mixing plane statistics computation. If Mixing Plane is not enabled, this option does not appear and a regular escape condition is always applied.

Vapor Condition Species Mode: Choose between Relative Humidity, Vapor Concentration or Case Settings for the vapor outlet boundary condition specification for reverse flows.

Relative Humidity [%]: Set the outlet relative humidity value for reverse flows.

Vapor Concentration [kg/m3]: Set the outlet vapor concentration value for reverse flows.

At the outlet boundary conditions, particles will escape the domain.

At the symmetry conditions, particles will be reflected.

For periodic boundaries, particles are re-injected at the associated face when leaving the domain using the transformation matrix of the periodic boundaries (position, velocity).

Number of Iterations: When Vapor is enabled, set the number of iterations for vapor resolution.

Iterations between Particle Update: When Vapor is enabled, this option lets you set the number of vapor iterations between two calculations of the particle trajectories and the update of the vapor source terms resulting from the particle resolution.

High Resolution Tracking: If enabled, accuracy of the tracking is improved by using the subtet approach, see High-Resolution Tracking under Tracking Settings for the Discrete Phase Model.

Use Length Scale:

Maximum Number of Tracking Steps: For each stream, the Lagrangian particle tracking ends up by reaching its final fate (escaped, trapped) or if this number of tracking time step is reached (incomplete fate).