Inlet Regions
Inlet regions differ from the standard inlets in two important and practical aspects – they can be defined anywhere inside the domain and they can be of arbitrary shape. This is of enormous help in the pre-processing phase and circumvents some of the nastiest elements from the previous chapter.
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.
More substantial information about the regions can be found in Theory and Advanced Features.
inletregions
{
inletregion
{
inletregion_type INREG_CIRCULAR
inletregion_phase 1
inletregion_motphs 7
inletregion_nrm "0.0 0.0 -1.0"
inletregion_vel 2.0
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_circle_rad 0.015
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_tvs_file time-velocity-series.txt
inletregion_tvs_offset 1.5
inletregion_tvs_latch true
}
}
- inletregion_type
- Specifying the type of the outlet region.
- inletregion_phase
- Phase ID of the fluid spawned by the inlet region.
- inletregion_motphs
- This option is applicable only to *_ARBOR (arbitrary orientation) inlets.
- inletregion_nrm
- Direction vector of the inlet region (can only point in +/- X, Y, Z).
- inletregion_vel
- Velocity magnitude of the inlet region.
- inletregion_stf_file
- Inlet region stencil file containing X, Y and Z coordinates of the seed inlet particles.
- 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.
- 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.
- 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.
- inletregion_extlen
- Defines the absolute length of the impose region in front of the inlet region (in the direction of the inlet normal).
- 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.
- inletregion_circle_rad
- Radius of the circular inlet region.
- inletregion_rectangle_len
- Length of the sides of the rectangular inlet region in each direction.
- inletregion_time_start
- Time at which the inlet region becomes active.
- inletregion_time_end
- Time at which the inlet region becomes inactive.
- inletregion_time_rampup
- Time during which the inlet velocity values goes from zero to the specified peak value.
- inletregion_time_rampdn
- Time during which the inlet velocity values goes down from a specified peak value to zero.
- inletregion_tvs_file
- For the inlet region there can be a Time Velocity Series file provided in .txt format, specifying an arbitrary shape of the inlet velocity magnitude as a function of time.
- inletregion_tvs_offset
- Provided that the TVS file is used for the inlet region, this values offsets the beginning of the TVS file in time.
- inletregion_tvs_latch
- Assuming that TVS file for the inlet region is provided, this command extends the last specified value in the TVS file until the end of the simulation.