UDF for KAPSEL (version 2.10) †
 UDF is a text file. One can browse and edit it using a text editor, but it.can be more easily handled with GOURMET. See the manuals below for general information on UDF.
 In the case of UDF used for KAPSEL, one must first choose the type of problem you want to simulate by selecting "constitutive_eq" from list below.
 Navier_Stokes: (sedimentation, diffusion, coagulation)
 Shear_Navier_Stokes: (rheology, chain in shear flow)
 Shear_Navier_Stokes_Lees_Edwards: (rheology, chain in shear flow)
 Electrolyte: (electrophoresis)
List of variables in UDF for KAPSEL (input.udf) †
constitutive_eq: type: {Navier_Stokes, Shear_Navier_Stokes, Shear_Navier_Stokes_Lees_Edwards,Electrolyte}
Navier_Stokes
 DX: Girid width (this is the unit of length)
 RHO: Density of fluid
 ETA: Viscosity of fluid
 kBT: Temperature of dispersion
 alpha_v: Scaling factor for fluctuating force (translation)
 alpha_o: Scaling factor for fluctuating torque (rotation)
Shear_Navier_Stokes
 DX: Girid width (this is the unit of length)
 RHO: Density of fluid
 ETA: Viscosity of fluid
 kBT: Temperature of dispersion
 alpha_v: Scaling factor for fluctuating force (translation)
 alpha_o: Scaling factor for fluctuating torque (rotation)
 External_field: type: {DC, AC}: Steady shear (DC) or Oscillatory shear (AC)
 DC
 shear_rate: Shear rate (DC)
 AC
 shear_rate: Max shear rate (AC)
 Frequency: Alternating frequency of shear flow
Shear_Navier_Stokes_Lees_Edwards
(This type implements LeesEdwards periodic boundary conditions for fluid fields under shear flow.)
 DX: Girid width (this is the unit of length)
 RHO: Density of fluid
 ETA: Viscosity of fluid
 kBT: Temperature of dispersion
 alpha_v: Scaling factor for fluctuating force (translation)
 alpha_o: Scaling factor for fluctuating torque (rotation)
 External_field: type: {DC, AC}: Steady shear (DC) or Oscillatory shear (AC)
 DC
 shear_rate: Shear rate (DC)
 AC(unpopulated)
 shear_rate: Max shear rate (AC)
 Frequency: Alternating frequency of shear flow
Electrolyte
 DX: Girid width (this is the unit of length)
 RHO: Density of fluid
 ETA: Viscosity of fluid
 kBT: Temperature of dispersion
 alpha_v: Scaling factor for fluctuating force (translation)
 alpha_o: Scaling factor for fluctuating torque (rotation)
 Dielectric_cst: Dielectric constant of fluid
 INIT_profile:
 Uniform: use uniform ionic densities as initial state.
 Poisson_Boltzmann: use optimal ionic densities as initial state by solving PoissonBoltzman Eq. for a given initial particle configuration in advance to start simulation.
 Add_salt: type: salt: salt is added, saltfree: no salt is added
 salt
 Valency_positive_ion: Valency of positive ions
 Valency_negative_ion: Valency of negative ions
 Onsager_coeff_positive_ion: Onsager transport coefficient of positive ions
 Onsager_coeff_negative_ion: Onsager transport coefficient of negative ions
 Debye_length: Debye screening length This causes the corresponding salt concentration to be specified automatically.
 saltfree
 Valency_counterion: Valency of counter ions
 Onsager_coeff_counterion: {Onsager transport coefficient of counter ions
 Electric_field: type: ON: apply external electric field, OFF: no external electric field
 ON: type: DC: apply steady electric field, AC: apply oscillatory electric field
 DC
 Ex: Intensity of electric field in xdirection
 Ey: Intensity of electric field in ydirection
 Ez: Intensity of electric field in zdirection
 AC
 Ex: Max intensity of electric field in xdirection
 Ey: Max intensity of electric field in ydirection
 Ez: Max intensity of electric field in zdirection
 Frequency: Alternating frequency of oscillatory electric field.
object_type: type: {spherical_particle, chain}
spherical_particle
 Particle_spec[]
 Particle_spec[0]: (0 means the 1st component)
 Particle_number: Number of particles
 MASS_RATIO: Density of particle / density of fluid
 Surface_charge: Valency of particles (total charge carried by a single particle in unit of electron charge)
chain
 Chain_spec[]
 Chain_spec[0] (0 meand the 1st component)
 Beads_number: Number of beads in a single chain
 Chain_number: Number of chains in a simulation box
 MASS_RATIO: Density of beads / density of fluid
 Surface_charge: Valency of beads (total charge carried by a single bead in unit of electron charge)
A_XI: Thickness of the particlefluid boundary
A: Radius pd particles or beads
gravity
 G: Gravitational acceleration
 G_direction: Select the direction in which gravity is applied from X , Y , Z.
EPSILON: Energy unit of LennardJones potential
LJ_powers: {12:6, 24:12, 36:18}: &color(blue){Set of power exponents of the
LennardJones potential};
mesh
 NPX: Defines the size of simulation box in xdirection as Lx=2^NPX
 NPY: Defines the size of simulation box in ydirection as Ly=2^NPY
 NPZ: Defines the size of simulation box in zdirection as Lz=2^NPZ
time_increment: type:
 auto: set delta_t automatically
 manual: set delta_t manually
auto
 factor: Set delta_t = factor * min [ rho/(eta k_max^2), 1/(k_B T Gamma_a k_max^2)],
manual
 delta_t: Set delta_t manually
switch
 ROTATION:
 ON: solve rotational motion of particles properly
 OFF: no rotational motion of particles
 HYDRO_int: Set Correct (other options are obsolete)
 Stokes: Set with advection (other options are obsolete)
 LJ_truncate:
 ON: LJ without attraction (WCA potential)
 OFF: LJ with attractive part
 NONE: no pair potential at all
 INIT_distribution: type:
 uniform_random: randomly generate initial particle positions
 random_walk: add some deviations to a perfect FCC lattice
 FCC: place particles on FCC lattice
 BCC: place particles on a BCC lattice
 user_specify: Set initial particle positions and velocities manually
 (If object_type = chain, all the above options are omitted and initial chain configurations are generated by selfavoided random walk unless user_specify is selected.)
 random_walk
 iteration: Number of trial iteration to avoid beadoverlapping in the process of random walk
 user_specify
 Particles[]
 (0 means properties of the 1st particle. If you want to inclease/decrease the number of particles, select "Edit" menu > "Add Array Elements"/"Delete Array Elements" to change the number of "Particles[]" box. Modify also "Particle_number" in "object_type" section to be consistent.)
 R
 x: xcomponent of initial particle position
 y: ycomponent of initial particle position
 z: zcomponent of initial particle position
 v
 x: xcomponent of initial particle velocity
 y: ycomponent of initial particle velocity
 z: zcomponent of initial particle velocity
 FIX_CELL
 x: {ON, OFF} Set ON to avoid the drift of center of gravity in xdirection
 y: {ON, OFF} Set ON to avoid the drift of center of gravity in ydirection
 z: {ON, OFF} Set ON to avoid the drift of center of gravity in zdirection
 pin: type:

 If you want to inclease/decrease the number of pined particles, select "Edit" menu > "Add Array Elements"/"Delete Array Elements" to change the number of "pin[]" and "pin_rot[]" box.
boundary_condition: type: Set full_periodic (other options are obsolete)
z_dirichlet
 wall_velocity_x: Unused
 wall_velocity_y: Unused
 wall_velocity_z: Unused
output
 GTS: Number of intervals between data saving
 Num_snap: Number of data saving. Total number of simulation step is GTS * Num_snap.
 AVS: {ON, OFF} Set ON if AVS data is needed. Huge disk space is used if ON.
 ON
 Out_dir: Name of subdirectory in which AVS data is saved. Make subdirectories ./"Out_dir" and ./"Out_dir"/avs in advance to run KAPSEL.
 Out_name: Set a name of AVS field data file "Out_name".fld
 File_Type: Select a file format of AVS data from BINARY or ASCII
E: Unused
t: Present time
Particles[] There is no data in this section of input UDF. Temporal particle positions and velocities are stored here in restart and output UDF.
resume
 Calculation: {NEW, CONTINUE}
 NEW: start a new simulation run
 CONTINUE: restart continuing simulation run from the end of the previous run.