Initial conditions

The following inputs are defined using the prefix ic:

	Description	Type	Default
regions	Regions used to define initial conditions. Supported region shapes include a box, cylinder, and sphere.	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<3>	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
granular_temperature	Adds specified granular temperature to particles in the IC region.	Real

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

	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<3>	0 0 0

For automatically generated particles, diameter and density distributions can be specified.

The following inputs control the diameter distribution and are defined with the prefix ic.[region_name].[solid_name].diameter

Note that diameter distributions must define a weighting type, please refer to ReferenceParticleDistributions.

	Description	Type	Default
distribution	Type of distribution for particle diameter in the IC region. This is only used for auto-generated particles. Options: constant - specified constant uniform - uniform distribution normal - normal distribution log-normal - log-noremal distribution custom - user-defined distribution	String	None
weighting	Weighting for diameter distribution. Options: number-weighted volume-weighted	String	N/A
bins	Number of bins used when discretizing the diameter distribution to approximate the number of particles within an initial condition region.	Int	64
constant	Monodisperse (single valued) particle diameter. Required for constant distributions.	Real	0
mean	Distribution mean. Required for normal and log-normal distributions.	Real	0
std	Distribution standard deviation. Required for normal and log-normal distributions.	Real	0
min	Minimum diameter to clip distribution. Required for normal, log-normal, and uniform distributions.	Real	0
max	Maximum diameter to clip distribution. Required for normal, log-normal, and uniform distributions.	Real	0
custom	File name that specifies either the cumulative or probability distribution. Required for custom distributions.	String	None
interpolate	For custom distributions, enable linear interpolation between discrete bins. This option is only available when the initial distribution probability is zero.	Bool	false

The following inputs control the density distribution and are defined with the prefix ic.[region_name].[solid_name].density:

	Description	Type	Default
distribution	Type of distribution for particle density in the IC region. This is only used for auto-generated particles. Options: constant - specified constant uniform - uniform distribution normal - normal distribution log-normal - log-noremal distribution custom - user-defined distribution	String	None
constant	Monodisperse (single valued) particle diameter. Required for constant distributions.	Real	0
mean	Distribution mean. Required for normal and log-normal distributions.	Real	0
std	Distribution standard deviation. Required for normal and log-normal distributions.	Real	0
min	Minimum density to clip distribution. Required for normal, log-normal, and uniform distributions.	Real	0
max	Maximum density to clip distribution. Required for normal, log-normal, and uniform distributions.	Real	0
custom	File name that specifies either the cumulative or probability distribution. Required for custom distributions.	String	None
interpolate	For custom distributions, enable linear interpolation between discrete bins. This option is only available when the initial distribution probability is zero.	Bool	false

The following input 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.distribution = constant
ic.bed0.my_solid0.diameter.constant =  100.0e-6

ic.bed0.my_solid0.density.distribution  = 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.distribution = uniform
ic.bed1.solid0.diameter.weighting = 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.distribution  = 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