Lagrangian Multiphase Field Functions Reference

This section describes the field functions that are made available to the simulation when the Lagrangian Multiphase model is used.

Field functions can be used to provide data for:

In many cases, a field function requires one or more specific Lagrangian phase models before it is available. These models are listed in brackets after the description. Some field functions also require that you activate the Lagrangian Multiphase solver expert property Temporary Storage Retained. These cases have "(Temporary)” after the description.

Aborted Parcel Count: The number of parcels that are aborted in each cell during tracking. If a parcel crosses between neighboring cells more than 200 times, it is aborted—removed from the simulation—to avoid performance degradation. Such parcels are most likely stuck in an infinite loop and indicate bad meshing and poorly resolved velocity fields. (Temporary)
Accretion Ratio: The ratio of the rate at which ice melts to the rate at which droplets impinge, according to $- {\dot{m}}_{m e l t} / {\dot{m}}_{d}$ .
Accumulated Stripping Mass: Mass accumulated from the surface but not stripped because of insufficient VOF mass in the cell.
Collision Efficiency: Random number used in the collision outcome algorithm to define the result of collision (bounce, graze, coalescence, reflexive separation). (NTC Collision Model Reference)
Collision Outcome: The outcome of a droplet's most recent collision: 0 =no collision, 1 = grazing separation, 2 = bounce, 3 = coalescence, 4 = reflexive separation. (NTC Collision Model Reference)
Contact Temperature: TBS
Contact Temperature 0|1: TBS
Droplet Dynamic Viscosity: The dynamic viscosity of the droplet material, $μ_{l}$ . (TAB Distortion, KHRT breakup, Primary Atomization, Droplet Flash-Boiling)
Droplet Latent Heat of Vaporization: The latent heat of vaporization of the droplet material, $L$ . (Droplet Evaporation)
Droplet Saturation Pressure: The absolute saturation pressure of the droplet material, $p_{s a t}$ . (Droplet Evaporation)
Droplet Surface Tension: The surface tension of the droplet material, $σ$ . (TAB Distortion, Secondary breakup, Primary Atomization, NTC Collision Model Reference)
Droplet Weber Number: The droplet Weber number, Eqn. (3147). (Secondary breakup)
Eddy Velocity Fluctuation: The difference between the instantaneous and Reynolds-Averaged velocity in eddies of the particles. It is the quantity $v'$ in Eqn. (2999). (Turbulent Dispersion) (Temporary)
Erosion Rate: The sum of Abrasive Wear Rate and Impact Wear Rate. It is the quantity $E_{f}$ in Eqn. (3306). (Erosion)
Film Transition Mark: Returns a value of 1 at every point on the cell face where the Droplet Film Transition model is active. Returns a value of 0 where a droplet has made the transition to film, deactivating the model. (Droplet Film Transition)
Incident Mass Flux of <Phase>: The mass flux of material particles of <phase> impinging on a boundary. (Material Particles)
Incident Mass Flux of <Component> of <Phase>: The mass flux of <component> of the material particles of <phase> impinging on a boundary. (Material Particles)
Incident Particle Flux of <Phase>: The rate of massless particles of <phase> impinging on a boundary. (Massless Particles)
Injector Index: The index of the injector which created each parcel.
Is Stripping: Whether stripping is occurring in a cell during a particular time-step. (VOF-Lagrangian User Stripping)
Lagrangian Boundary Heat Transfer: The rate of heat transfer to the boundary from incident Lagrangian parcels. (Two-Way Coupling, Energy, Impingement Heat Transfer) (Temporary)
Lagrangian Charge Density: The total particle charge per unit cell volume. (Coulomb Force, Two-Way Coupling.)
Lagrangian Energy Source: The rate of energy transfer to the continuous phase from all Lagrangian phases with a Two-Way Coupling model. It is the quantity $S_{E}$ in Eqn. (3052) and Eqn. (3054). (Material Particles, Two-Way Coupling, Energy) (Temporary)
Lagrangian Mass Source: The rate of mass transfer to the continuous phase from all Lagrangian phases with a Two-Way Coupling model. It is the quantity $S_{m}$ in Eqn. (3047) and Eqn. (3049). (Material Particles, Two-Way Coupling, Mass Transfer) (Temporary)
Lagrangian Momentum Source: The rate of momentum transfer to the continuous phase from all Lagrangian phases with a Two-Way Coupling model. It is the quantity $S_{v}$ in Eqn. (3043) and Eqn. (3045). (Material Particles, Two-Way Coupling) (Temporary)
Lagrangian Species Source (<Species>): The rate of mass transfer of <species> to the continuous phase from all Lagrangian phases with a Two-Way Coupling model. (Material Particles, Two-Way Coupling, Mass Transfer, Species) (Temporary)
Mass Flow Rate: The rate at which mass flows through a boundary.
Mass Flow Rate of <Phase>: The rate at which mass of <phase> flows through a boundary. (Eqn. (462))
Mass Flux: The rate per unit area at which mass flows through a boundary.
Mass Flux of <Phase>: The rate per unit area at which mass of <phase> flows through a boundary.
Number Density of <Phase>: The number of massless particles of <phase> per unit volume of space. (Massless Particles)
Number of Collisions: The number of collisions in a cell for a particular time-step. (No Time Counter) (Temporary)
Parcel Centroid: The position of parcels, $r_{π}$ .
Parcel Index: A unique identifier for each parcel. The index is unique within a Lagrangian phase.
Parcel Intersection Face Normal: The outward pointing normal of the cell face that the parcel currently intersects. If the normal is a zero vector, it means that the parcel is inside a cell, not at any face. This function can be used to define properties such as coefficients of restitution or composite mode probabilities.
Parcel Mass: The mass of parcels, $m_{π} = {n_{π} m}_{p}$ . (Material Particles). (Unsteady)
Parcel Mass Flow Rate: The mass of parcels, ${\dot{m}}_{π} = {{\dot{n}}_{π} m}_{p}$ . (Material Particles). (Steady)
Parcel Size: Radius $R_{π}$ of an equivalent sphere of mass and density equal to that of the parcel $R_{π} = 0.5 D_{p} \sqrt[3]{n_{π}}$ , where $n_{π}$ is the Particle Count. This field function sets the display size of parcels in scenes when the Point Scale Mode of a scalar displayer is set to Particle Model. This function is also the default function for the Point Size Scale Field when Point Scale Mode is set to Scalar. In steady simulations, Parcel Size evaluates to zero. Do not use Parcel Size for scaling parcel displays in steady simulations.
Parcel Time Step: The local time-step, $δ t_{p}$ in Eqn. (3326) and Eqn. (3327).
Parcel Volume: The volume of parcels, $V_{π} = n_{π} V_{p}$ . (read-only). (Unsteady)
Parcel Volume Flow Rate: The volume of parcels, ${\dot{V}}_{π} = {\dot{n}}_{π} V_{p}$ . (Material Particles). (Steady)
Particle Activity Coefficient: The computed activity coefficients of mixture components if the modified UNIFAC model option is activated. (Droplet Evaporation).
Particle Charge: The particle charge $q$ . (Coulomb Force).
Particle Clift Drag Coefficient: The Clift drag coefficient $C_{d}$ for the particle. See Eqn. (2969).
Particle Count: The number of particles that are represented by a parcel, $n_{π}$ . (Unsteady)
Particle DiFelice Drag Coefficient: The DiFelice drag coefficient $C_{d}$ for the particle. See Eqn. (2971).
Particle Density: The density of the particle material, $ρ_{p}$ . (Material Particles)
Particle Diameter: The diameter of particles $D_{p}$ . If you are using this field function together with a wall-bound Lagrangian phase, the particle diameter that the field function provides corresponds to the diameter of the equivalent sphere, $2 r_{s p h e r e}$ in Eqn. (3005).(Material Particles)
Particle Drag Force: The drag force on a particle, $F_{d}$ . (Drag Force)
Particle EMMS Drag Coefficient: The EMMS drag coefficient $C_{d}$ for the particle in Eqn. (2975). (EMMS Drag Coefficient)
Particle Enthalpy: The energy per unit mass of a particle. (Two-Way Coupling)
Particle Ergun Drag Coefficient: The Ergun drag coefficient $C_{d}$ for the particle. See Eqn. (2974).
Particle Flow Rate: The rate at which particles flow along parcel tracks, ${\dot{n}}_{π}$ . (Steady)
Particle Gidaspow Default Drag Coefficient: The Gidaspow drag coefficient is equal to the Wen-Yu coefficient Eqn. (2973) or the Ergun coefficient Eqn. (2974), depending on the value of the void fraction $ϵ$ .
Particle Haider Levenspiel Drag Coefficient: The Haider Levenspiel drag coefficient $C_{d}$ for the particle. See Eqn. (2976).
Particle Incidence Angle: The angle between the particle velocity vector and the plane of face on which it is incident, if any, $θ = asin (v_{p} \cdot n / | v_{p} |)$ . This function is provided for use in boundary condition expressions, it is not available for visualization, reporting, or recording on the track file. (Material Particles)
Particle Liu Drag Coefficient: The Liu dynamic drag coefficient $C_{d}$ for the particle. See Eqn. (2967).
Particle Mass: The mass of single particles, $m_{p}$ . Note, not the mass of parcels. (Material Particles)
Particle Mass Fraction of <Species>: The mass fraction, $Y_{p i} = {m_{p i} / m}_{p}$ , of species i in a single particle.
Particle Molar Concentration of <Species>: The molar concentration, $C_{p i} = ρ_{p} Y_{p i} / W_{p i}$ , of species i in a single particle, where $ρ_{p}$ is the particle mixture density, $Y_{p i}$ is the species mass fraction, and $W_{p i}$ is the species molecular weight.
Particle Mole Fraction of <Species>: The mole fraction, $X_{p i} = Y_{p i} W_{p} / W_{i}$ , of species i in a single particle, where $Y_{p i}$ is the species mass fraction, $W_{p}$ is the molecular weight of the particle mixture, and $W_{p i}$ is the molecular weight of the species.
Particle Nusselt Number: The non-dimensional heat transfer coefficient of particles, ${Nu}_{p}$ , defined in Eqn. (3025). (Lagrangian Energy)
Particle Permittivity: The relativty permittivity of the particle $ϵ_{r}$ . (Field Charging).
Particle Porosity: The porosity of particles within the Lagrangian phase. (Particle Porosity)
Particle Residence Time: The “age” of particles as measured from time of injection.
Particle Reynolds Number: The quantity ${Re}_{p}$ in Eqn. (2966). (Material Particles)
Particle Sherwood Number: The non-dimensional mass transfer conductance, ${S h}_{p}$ , defined in Eqn. (3238). (Mass Transfer)
Particle Schiller-Naumann Drag Coefficient: The Schiller-Naumann drag coefficient for the particle. See $C_{d}$ in Eqn. (2965).
Particle Slip Velocity: The velocity deficit of particles relative to the continuous phase, $v_{s} = v - v_{p}$ . (Material Particles)
Particle Smooth Source Group: Unsigned integer ID for the cluster to which a cell belongs when the cell cluster method is active for two-way coupling. (Two-Way Coupling and Two-Way Coupling Solver)
Particle Smooth Source Weight: The volume fraction of a cell relative to the total volume of the cluster in which it belongs. The fluid source terms generated by particles are summed over the cluster, then distributed back to the cell using this factor. The result is that the source contribution per unit volume is uniform across each cluster. (Two-Way Coupling and Two-Way Coupling Solver)
Particle Specific Heat: The specific heat of particles. (Lagrangian Energy)
Particle Surface Area: The surface area of single particles, $A_{s}$ . Note, not the surface area of parcels. (Material Particles)
Particle Temperature: The temperature of particles, $T_{p}$ . (Lagrangian Energy)
Particle Velocity: The absolute velocity of particles, $v_{p}$ .
Particle Volume: The volume of single particles, $V_{p} = m_{p} / ρ_{p}$ . Note, not the volume of parcels. (Material Particles)
Particle Wen-Yu Drag Coefficient: The Wen-Yu drag coefficient for the particle. See $C_{d}$ in Eqn. (2973).
Primary Atomization Status: A parcel has a value of 1 while primary atomization is in progress. When primary atomization is complete, or when primary atomization is bypassed because the Weber number is smaller than ${We}_{cr}$ in Eqn. (3114), so that the parcel has moved onto secondary breakup, the value is 0.(Huh Atomization)
Relative Weber Number: The relative Weber number for a droplet's most recent collision.
Stripping Continuity Source: Rate of mass transfer from the VOF phase to the Lagrangian phase.
Stripping Energy Source: Rate of energy transfer from the VOF phase to the Lagrangian phase.
Stripping Momentum Source: Rate of momentum transfer from the VOF phase to the Lagrangian phase.
Stripping Species Source <Species>: Rate of mass transfer of <Species> from the VOF phase to the Lagrangian phase.
Stuck Mark: A particle stuck to a cell face has a Stuck Mark value of 1. Otherwise, the value is 0. See Stick Mode. (Bai-ONERA, Bai-Gosman, Droplet Film Transition)
TAB Distortion: The normalized distortion of droplets, $y$ in Eqn. (3110). (TAB Distortion) (Temporary)
TAB Distortion Rate: The rate of change of TAB Distortion, $\dot{y}$ . (TAB Distortion) (Temporary)
Void Fraction: The fraction of the cell volume available to the fluid, unoccupied by a solid or dispersed phase.
Volume Fraction of <Phase>: The volume of material particles of <phase> per unit volume of space. (Material Particles)