DROPLETPHASE

Explicit solver for droplets which may interact and collect as water films along boundaries

For using the DROPLETPHASE solver, choose the kind of problem as

KOP(1) = DROPLETPHASE H:MIN_FACTOR(1.0) CORNER_TREATMENT_VERSION:N

The value H:MIN_FACTOR is optional and can be set between 0 and 1. It allows to adaptively reduce the smoothing length H, if too many points collect at the same place. This can prevent an extreme increase in the number of neighbor points, which contributes to a significantly improved performance in such situations. The default value is 1, which means that H is not changed. If a value smaller than 1 is given, the smoothing length can be reduced no further than to the value given in the input file times the specified factor.

The value of CORNER_TREATMENT_VERSION:N is also optional and addresses only those points collecting as thin layer on a rigid surface (LiquidLayer). The value of N can be chosen between 0 and 5, see SlidingThroughCorners. If not set it defaults to 4.

Each point represents a volume of material. We assume droplet form, the volume is given with respect to the given diameter %ind_d30%. Since points in the DROPLETPHASE represent discrete physical entities rather than numerical discretization points, they are not subject to the same point organization as, for example, the LIQUID phase.

The time step criteria for DROPLETPHASE chambers are described in TimeStepCriteria

Solver capabilities

There are several types of droplet dynamics which can be modeled within the DROPLETPHASE solver:

  • Free flight droplets

    This movement is governed by applying gravity forces or the Darcy ansatz as dynamic of freely flying droplets. See FreeFlight

  • Liquid layer on a wall

    On slip walls, a liquid layer ansatz can be employed, where droplets collect and form a thin film. See LiquidLayer

  • Collisions between droplets

    DropletCollisions (droplet-droplet and droplet-wall) are modeled by integrating the interaction forces (Discrete Element Model, soft shell approach). See DropletCollisions

  • Locked Points on a wall

    For walls, a definition can be given, when points shall be locked there. This can be used for modelling clustering (similar to a hard shell approach) . See DROPLETPHASE_LockedPoints_Collision

Most of the DROPLETPHASE models incorporate droplets in FreeFlight. The modeling of LiquidLayer, DropletCollisions and Locked points are only conditionally compatible.

Simulation Models

Online Examples

List of members:
TimeStepCriteria DROPLETPHASE - Time step criteria
FreeFlight DROPLETPHASE - Modeling of free flight droplets
LiquidLayer DROPLETPHASE - Modeling of liquid layers
DropletCollisions DROPLETPHASE - Modeling of collisions between droplets
Parcels DROPLETPHASE - Auto clustering particles to speed up simulations
This item is referenced in:
FAQ overview of frequently asked questions and hints for solution
CollidingDropletsInCone Colliding droplets in cone geometry
ChannelWithFilter Coupled simulation of droplets and air in a channel with filter
WaterSand A jet of water and sand hits a plate
LiquidLayerExample Droplets forming a liquid layer on a plate
%ind_Vi% volume represented by a point, unit=m^3
%ind_grad_hwf(1)% if droplets collect on a boundary: gradient of height of accumulated water film, x-component [1]
%ind_grad_hwf(2)% if droplets collect on a boundary: gradient of height of accumulated water film, y-component [1]
%ind_grad_hwf(3)% if droplets collect on a boundary: gradient of height of accumulated water film, z-component [1]
%ind_hwf% if droplets collect on a boundary: height of accumulated water film [m]
%ind_lap_hwf% if droplets collect on a boundary: Laplacian of the height in tangential direction (i.e. curvature of the accumulated water film) [1/m]
%ind_MUE_relax% DROPLETPHASE: locked points: slope of the forces (viscous, same sense as ind_ETA) before reaching the Coulomb friction force given by ind_MUE
%ind_mult% Multiplicity: Number of particles represented by this parcel / cluster.
%ind_tContact% DROPLETPHASE: contains the contact time of prospective collisions
dist_parceling (experimental / Under development) Maximum relative distance to initiate parceling
dist_parceling_FreeFlight (experimental / Under development) Maximum relative distance to initiate parceling
DROPLETPHASE_nbTSforParceling Number of time steps after which parceling will be done
IPC_ReadMultipleFramesDuringRuntime (experimental) switch to enable read in of multiple frames for ReadInPointCloud
ORGANIZE_DistanceToBoundary_Version define version number for distance-to-boundary computations
dist_parceling (experimental / Under development) Maximum relative distance to initiate parceling (UCVO)
dist_parceling_FreeFlight (experimental / Under development) Maximum relative distance to initiate parceling in free flight (UCVO)
DROPLETPHASE_MaxEquivalentParcelDiameter Limiting maximum equivalent parcel diameter for parceling in DROPLETPHASE (UCVO)
DROPLETPHASE_MaxRelativeParcelVelocity Limiting maximum relative parcel velocity for parceling in DROPLETPHASE (UCVO)
DROPLETPHASE_MinNeighboursForParceling Limiting number of neigbors to trigger clustering in DROPLETPHASE (UCVO)
DROPLETPHASE_ParcelingDiameterClasses defines classes for diameters for parceling. And parceling is only done whent two parcels are in the same class.
COEFF_dt_coll time step criterion from interaction model (DROPLETPHASE only) (UCV)
COEFF_dt_d30 time step criterion depending on %ind_d30% (DROPLETPHASE only) (UCV)
COMP_DropletphaseSubcycles switch for DROPLETPHASE subcycling (UCV)
COMP_DropletphaseWithDisturbance disturbance for DROPLETPHASE (UCV)
dist_parceling (experimental / Under development) Maximum relative distance to initiate parceling (UCVO)
dist_parceling_FreeFlight (experimental / Under development) Maximum relative distance to initiate parceling in free flight (UCVO)
DP_UseOnlyRepulsiveContactForce switch regarding attractive forces in spring-damper model (UCV)
IDENT (required) how to handle the geometry part during point cloud organization
%IDENT_none% inactive BE (IDENT)
%IDENT_void% invisible precision measurement BE (IDENT)
%IDENT_BlindAndEmpty% invisible flux measurement BE (IDENT)
%IDENT_wall% non-moving wall points BE (IDENT)
%IDENT_slip% movable wall points BE (IDENT)
%IDENT_inflow% inflow BE (IDENT)
%IDENT_outflow% outflow BE (IDENT)
%IDENT_ThinFilm% wall layer points (IDENT)
%TOUCH_reflection% points reflected at boundary
%BND_slip% Slip liquid layers for Dropletphase
%BND_COLLISION% velocity boundary condition to represent collisions
DROPLETPHASE_LockedPoints_Collision Mixed definition of repulsion / locking of DROPLETPHASE points at walls or clusters
DROPLETPHASE_LockedPoints_Detachment releases DROPLETPHASE points from the %IDENT_locked% state
DROPLETPHASE_LockedPoints_Modification modify function values of DROPLETPHASE points in the %IDENT_locked% state
COMP_DropletphaseParcels (experimental / Under development) cluster particles together in DROPLETPHASE
BasedOnVolumeFlux generate a sequence of spherical droplets based on user defined volume flux
nbsum() sum over points in neighbor list
opDrPh() various operators (diffusion, moment) on the DROPLETPHASE
%INTEGRATION_INT% volume integration of a functional with respect to a given material
%INTEGRATION_INT_TIME% volume and time integration of a functional with respect to a given material
%INTEGRATION_FLUX% flux integration of a functional by counting the MESHFREE points that slip over a given control surface
%INTEGRATION_FLUX_IN% flux integration of a functional by counting the newly injected MESHFREE points
%SUMMATION_INT% summation of given function values based on all MESHFREE points with respect to given material flags
%AVERAGE_INT% average of a functional based on all MESHFREE points with respect to given material flags
Solvers Select the solver base on a physical model
DarcyConstant coupling parameter for porous media [kg/(s*m^3)]
%MED_LIQUID_FILM% viscosity definition in liquid films [Pa*s]
ParticleInteraction defines the dynamics of particle-particle interaction within the DROPLETPHASE as material property
ReadInPointCloud read in an already existing point cloud from file
EnSight read in already existing point cloud from EnSight format
%INTEGRATION_FLUX_DROPLETPHASE% flux integration of a functional by counting the DROPLETPHASE points that slip over a given control surface
%MASSFLOW_DROPLETPHASE% mass flux integration of a functional by counting the DROPLETPHASE points that are injected at all inflow surfaces
Beta Latest release notes for the MESHFREE beta executables
All Complete release notes for the MESHFREE beta executables
Stable Release notes for the MESHFREE stable executables
NamesOfStopWatches currently implemented stop watches
Numerics PDE to be solved and the meshfree algorithms to solve the PDE
DROPLETPHASE Explicit solver for droplets which may interact and collect as water films along boundaries
TimeStepCriteria DROPLETPHASE - Time step criteria
FreeFlight DROPLETPHASE - Modeling of free flight droplets
LiquidLayer DROPLETPHASE - Modeling of liquid layers
DropletCollisions DROPLETPHASE - Modeling of collisions between droplets
Parcels DROPLETPHASE - Auto clustering particles to speed up simulations