# Inlet Regions

Defines inlet region parameters.

Inlet regions differ from the standard inlets in two ways. They can be defined anywhere inside the domain and they can be of arbitrary shape. They can also be prescribed through specified velocity of the flow, mass or volumetric flow (in units of m/s, kg/s or m3/s).

Inlet regions can be defined in rectangular, circular or custom shape. While the first two require just geometric description of the region as an input, the custom shaped region requires a “stencil” of particles in form of a separate .txt file. The .txt file for the custom shaped inlet region simply contains the coordinates (x, y, z) of the particles which are to be inserted into the domain. The stencil in that case behaves as a source of particles.

The only limitation to the inlet regions is that they must be planar, even in the custom shape or arbitrary orientation scenario.

inletregions
{
inletregion
{
inletregion_type            INREG_CIRCULAR
inletregion_phase           1
inletregion_motphs          7
inletregion_nrm             "0.0 0.0 -1.0"
inletregion_stttyp          vel
inletregion_sttval          0.0
inletregion_stf_file        "stencil-file.txt"
inletregion_prefilled       true
inletregion_indexsim        false
inletregion_extend          true
inletregion_extlen          0.1
inletregion_extlenodx       4
inletregion_cnt             "0.04 0.0105 0.03"
inletregion_rectangle_len   "0.03 0.04 0.0"
inletregion_time_start      0.0
inletregion_time_end        0.05
inletregion_time_rampup     0.01
inletregion_time_rampdn     0.025
inletregion_tss_file        time-state-series.txt
inletregion_tss_offset      0.0
inletregion_tss_latch       false
inletregion_temp            0.0
inletregion_extpre          false
inletregion_extpst          false
}
}
inletregion_type
Specifying the type of the outlet region.
There are five options: INREG_CIRCULAR, INREG_RECTANGULAR, INREG_CUSTOM, INREG_CIRCULAR_ARBOR, and INREG_RECTANGULAR_ARBOR.
When specifying INREG_CUSTOM, you must provide the stencil file (inletregion_stf_file).
inletregion_phase
Phase ID of the fluid spawned by the inlet region.
inletregion_motphs
This option is applicable only to *_ARBOR (arbitrary orientation) inlets.
It specifies the MOVINGWALL phase number which the probe is supposed to follow.
inletregion_nrm
Direction vector of the inlet region (can only point in +/- X, Y, Z).
inletregion_stttyp
This command is optional.
Type of inlet region state. vel for velocity, vfl for volume flowrate, mfl for mass flowrate.
Options: vel, vfl, mfl
Default: vel
inletregion_sttval
State magnitude of the inlet region.
If defined, inletregion_tss_file takes precedence over this command.
Default: 0.0
Unit: [m/s] or [kg/s] or [m3/s]
inletregion_stf_file
Inlet region stencil file containing X, Y and Z coordinates of the seed inlet particles.
Using the stencil file, the shape of the inlet can be an arbitrary 2-dimensional shape.
inletregion_prefilled
This command notifies the solver that at the time of the inlet region activation, there are fluid particles overlapping at the seeding coordinates of the inlet. If so, the command should be set to true.
Options: true/false
Default: true
inletregion_indexsim
Setting this value to true will result in the particles introduced by this inlet to follow the particle ID numbering in accordance with particle ID’s present in the domain at the time.
This command has no influence on the particle spawning or other related inlet parameters.
Options: true/false
Default: false
inletregion_extend
In order for the inlet region to function properly in a multiphase environment and reduce potential local instabilities, an impose region should be created in front of the inlet stencil particles (in the direction of the inlet normal). Setting this command to true automatically creates that impose region.
This option is not necessary in a single phase case, assuming that the inlet is located in a particle vacuum.
Options: true/false
Default: true
inletregion_extlen
Defines the absolute length of the impose region in front of the inlet region (in the direction of the inlet normal).
Unit: [m]
inletregion_extlenodx
Defines the relative length of the impose region in front of the inlet region (in the direction of the inlet normal) as a function of dx (particle pitch).
inletregion_cnt
X, Y and Z coordinates of the inlet region center.
The center is defined for both circular and rectangular inlet regions (not needed for the custom file).
Unit: [m]
Radius of the circular inlet region.
Not applicable to rectangular or custom inlet regions.
Unit: [m]
inletregion_rectangle_len
Length of the sides of the rectangular inlet region in each direction.
The length along the inletregion_nrm direction is ignored.
Unit: [m]
inletregion_time_start
Time at which the inlet region becomes active.
Unit: [s]
inletregion_time_end
Time at which the inlet region becomes inactive.
Unit: [s]
inletregion_time_rampup
Time during which the inlet velocity value goes from zero to the specified peak value.
Unit: [s]
inletregion_time_rampdn
Time during which the inlet velocity value goes down from a specified peak value to zero.
Unit: [s]
inletregion_tss_file
For the inlet region there can be a Time State Series (TSS) file provided in ASCII format, specifying an arbitrary shape of the inlet flow magnitude as a function of time.
TSS file has a 2-column format specifying time (column 1) and magnitude of the velocity/mass/volume flow (column2) with a space as delimiter.
inletregion_tss_offset
Provided that the TSS file is used for the inlet region, this value offsets the beginning of the TSS file in time.
For example, specifying a value of 2.0 for this command will offset the TSS file by two seconds, such that the starting time of the TSS file effect is two seconds.
Default: 0.0
Unit: [s]
inletregion_tss_latch
Assuming that the TSS file for the inlet region is provided, this command extends the first and/or last specified value in the TSS file until start and/or end of the simulation, respectively.
Example: The last entry in the TSS file specifies a magnitude of 5 m/s at two seconds. The total specified simulation duration is six seconds (t_end = 6 s). When this command is set to true, the velocity magnitude will remain 5 m/s until the simulation ends even though the TSS file ends at t = 2 s.
Default: false
inletregion_temp
Temperature of the inlet region.
Specifies the inlet region fluid temperature. The specified temperature spawned by the inlet region, overrides the fluid phase temperature defined in the phases section. Leaving the value blank or excluding this keyword, reverts back to using temperature from phases section.
Default: temp_0of phase.
Unit: [K]
inletregion_extpre
Notifies the solver about inlet region extension status before the inlet start time.
Options: true/false
Default: false
inletregion_extpst
Notifies the solver about inlet region extension status after the inlet start time.
Options: true/false
Default: false