Initial conditions

The following inputs are defined using the prefix ic:

Description

Type

Default

regions

Regions used to define initial conditions.

Strings

None

allow_regions_overlap

If enabled, particles will be generated/initialized more than once on areas where the IC regions intersect. This only applied to particle initializations. Fluid initial conditions are applied in the order defined in the inputs file, with later regions overwriting earlier ones.

Int

1

Fluid settings

For each initial condition region, the fluid inputs are defined using the compound prefix ic.[region_name].[fluid_name]:

Description

Type

Default

volfrac

Volume fraction [required]

Real

0

density

Fluid density

Real

0

velocity

Velocity components

Reals

0 0 0

pressure

Fluid pressure

Real

0

temperature

Fluid temperature

Real

0

species.[species_name]

Mass fraction of species_name. Species must be a fluid species.

Real

0

Solids settings

For each initial condition region, general solids inputs are defined using the compound prefix ic.[region_name]:

Description

Type

Default

solids

Name of solid type in IC region. Only one solid is allowed in an IC region.

String

None

packing

Specifies how auto-generated particles are placed in the IC region:

Options:

  • hcp - hex-centered packing

  • pseudo_random – random packing using a fixed random seed

  • random – random packing (not repeatable)

  • oneper – one particle per cell

  • eightper – eight particles per cell

  • n-cube – n^3 particles per cell where n is an integer

(NOTE: oneper is equivalent to 1-cube and eightper

to 2-cube)

String

None

For each initial condition region, the solid inputs are defined using the compound prefix ic.[region_name].[solid_name]: Note that diameter distributions must define a weighting type, please refer to ReferenceParticleDistributions.

Description

Type

Default

volfrac

Volume fraction

Real

0

temperature

Temperature

Real

0

species.[species_name]

Mass fraction of species_name. Must be a solid species.

Real

0

velocity

Velocity components

Reals

0 0 0

diameter

Method to specify particle diameter in the IC region. This is only used for auto-generated particles.

Options:

  • constant - specified constant

  • uniform - uniform distribution

  • normal - normal distribution

  • custom - user-defined distribution

String

None

type

Distribution weighting.

Options:

  • number-weighted

  • volume-weighted

String

N/A

bins

Number of bins used when discretizing the distribution to approximate the number of particles within an initial condition region.

Int

64

diameter.constant

Monodisperse (single valued) particle diameter. Required for constant distributions.

Real

0

diameter.mean

Distribution mean. Required for normal distributions.

Real

0

diameter.std

Distribution standard deviation. Required for normal distributions.

Real

0

diameter.min

Minimum diameter to clip distribution. Required for normal distributions and uniform distributions.

Real

0

diameter.max

Maximum diameter to clip distribution. Required for normal distributions and uniform distributions.

Real

0

diameter.custom

File name that specifies either the cumulative or probability distribution. Required for custom distributions.

String

None

density

Method to specify particle density in the IC region. This is only used for auto-generated particles.

Options:

  • constant - specified constant

  • uniform - uniform distribution

  • normal - normal distribution

  • custom - user-defined distribution

String

None

density.constant

Monodisperse (single valued) particle density. Required for constant distributions.

Real

0

density.mean

Distribution mean. Required for normal distributions.

Real

0

density.std

Distribution standard deviation. Required for normal distributions.

Real

0

density.min

Minimum diameter to clip distribution. Required for normal distributions and uniform distributions.

Real

0

density.max

Maximum diameter to clip distribution. Required for normal distributions and uniform distributions.

Real

0

density.custom

File name that specifies either the cumulative or probability distribution. Required for custom distributions.

String

None

The following inputs must be preceded by the prefix mfix:

Description

Type

Default

particle_init_type

Particle initialization method.

Options:

  • Auto - automatic particle generation

  • ASCIIFile - read particle data from file particle_input.dat

String

ASCIIFile

The following input must be preceded by the prefix particles:

Description

Type

Default

removeOutOfRange

Remove particles at initialization that are touching a wall.

Int

1

Below is an example for specifying an initial condition for a fluid (fluid) and one solid (solid0).

mfix.particle_init_type = Auto

particles.removeOutOfRange = 1

ic.regions  = bed0  bed1

ic.bed0.fluid.volfrac   =  0.725
ic.bed0.fluid.density   =  1.0
ic.bed0.fluid.velocity  =  0.015  0.00  0.00
ic.bed0.fluid.temperature =  383.0
ic.bed0.fluid.species.CO  =  0.3
ic.bed0.fluid.species.CO2 =  0.2
ic.bed0.fluid.species.O2  =  0.5

ic.bed0.solids  = my_solid0

ic.bed0.packing = pseudo_random

ic.bed0.my_solid0.volfrac  =  0.275
ic.bed0.my_solid0.temperature  =  400.0
ic.bed0.my_solid0.species.Fe2O3 =  0.4
ic.bed0.my_solid0.species.FeO   =  0.6

ic.bed0.my_solid0.velocity =  0.00  0.00  0.00

ic.bed0.my_solid0.diameter = constant
ic.bed0.my_solid0.diameter.constant =  100.0e-6

ic.bed0.my_solid0.density  = constant
ic.bed0.my_solid0.density.constant  = 1000.0

ic.bed1.fluid.volfrac   =  0.925
ic.bed1.fluid.density   =  1.0
ic.bed1.fluid.velocity  =  0.015  0.00  0.00
ic.bed1.fluid.temperature =  383.0
ic.bed1.fluid.species.CO  =  0.5
ic.bed1.fluid.species.CO2 =  0.5
ic.bed1.fluid.species.O2  =  0.0

ic.bed1.solids  = solid0
ic.bed1.packing = pseudo_random

ic.bed1.solid0.volfrac  =  0.075
ic.bed1.solid0.temperature  =  450.0
ic.bed1.solid0.species.Fe2O3 =  0.0
ic.bed1.solid0.species.FeO   =  1.0

ic.bed1.solid0.velocity =  0.10  0.00  0.00


ic.bed1.solid0.diameter = uniform
ic.bed1.solid0.diameter.type = number-weighted
ic.bed1.solid0.diameter.bins = 20
ic.bed1.solid0.diameter.min =   90.0e-6
ic.bed1.solid0.diameter.max =  110.0e-6

ic.bed1.solid0.density  = normal
ic.bed1.solid0.density.mean  = 900.0
ic.bed1.solid0.density.std  =   30.0
ic.bed1.solid0.density.min  =  800.0
ic.bed1.solid0.density.max  = 1000.0