Outlet Regions

Outlet regions mimic the behavior of outlet and simple outlet using a combination of removal and extended regions. They allow particles of any phase to be removed from anywhere within the computational domain.

Cylindrical and rectangular shaped outlet regions can optionally have an extension region, similar to inlet region extensions, which can define either velocity or acceleration within its volume.

A removal region is a region wherein any particle belonging to a list of designated phases will be removed if it enters this region.

An extension is an extended region in the opposite direction of the outlet region's normal where a constant particle velocity or acceleration in the normal direction is enforced.

Spherical outlet region cannot have an extension and acts as a simple particle sink. Every particle that enters an outlet region will be removed from the simulation permanently.

For a more information, refer to Outlet Regions in the Theory Manual.

Commands

outletregions
{
    outletregion
    {
        outletregion_phase          "1 2 3 6"
        outletregion_type           OUTREG_SPHERE               
        outletregion_cnt            "0.0 0.3 0.0" 

        outletregion_sphere_rad     0.1   
          
        outletregion_exttyp         noext                       
        outletregion_extpre         false      
        outletregion_extpst         true 
        outletregion_extlen         0.1  
        outletregion_extlenodx      4   
        outletregion_extstt         1.55

        outletregion_nrm            "1.0 0.0 0.0"            
        outletregion_cylinder_rad   0.5                       
        outletregion_cylinder_hgt   5.0
        
        outletregion_cuboid_len     "0.1 0.2 0.3"              
                                                     
        outletregion_tss_file       time-state-series.txt       
        outletregion_tss_offset     1.5                        
        outletregion_tss_latch      true   

        outletregion_time_start     0.0      
        outletregion_time_end       0.05       
        outletregion_time_rampup    0.01                
        outletregion_time_rampdn    0.025   
    }
}

Definitions

Command Contents SI Unit Example
outletregion_phase Specifies phase type. By default, all FLUID type phases are included.
Note:
  • This command is optional.
  • Generally, any phase type can be specified. The outlet region will remove any WALL or MOVINGWALL phase types as well, if specified.
  
outletregion_type Type of the outlet region.
Options
  • OUTREG_SPHERE
  • OUTREG_CUBOID
  • OUTREG_CYLINDER
  
outletregion_cnt Center of the outlet region can have different definitions, depending on the type of the outlet region which is being used.
Options
  • OUTREG_SPHERE – in this case the command is center of the sphere.
  • OUTREG_CYLINDER – in this case the command is the center of the cylinder base where normal points toward the removal region.
  • OUTREG_CUBOID when no extension and no normal are specified – the command is then representing the volumetric center of cuboid.
  • OUTREG_CUBOID and a defined normal – the command is the center of the face perpendicular to normal and points toward the removal region.
  
outletregion_sphere_rad If OUTREG_SPHERE type is selected, this command defines the radius of the sphere. [m]
outletregion_exttyp If OUTREG_CYLINDER or OUTREG_CUBIOD are selected, this determines the type of the extension that you want to use.
Options
  • noext
  • setacc
  • setvel
  
outletregion_extpre If set to true, the extended region will be active before the outlet region start time.
Note: This command is optional.

Default = false

  
outletregion_extpst If set to true, the extended region will be active after the outlet region end time.
Note: This command is optional.

Default = false

  
outletregion_extlen Defines the absolute length of the extension in front of the outlet (removal) region (opposite of the direction of the outlet normal). [m]
outletregion_extlenodx Defines the relative length of the extension in front of the outlet (removal) region (opposite of the direction of the outlet normal) as a function of dx.  
outletregion_extstt Determines the magnitude of the velocity or the acceleration, depending on which extension type was selected.
Attention:
  • For velocity this number must be a positive value.
  • For acceleration it can be any number.
  
outletregion_nrm Direction vector of the outlet region normal to the surface between extension region and removal region.
Note: It must point toward removal region and align with +/- X, Y, Z axes.
Options
  • OUTREG_CUBOID and no extension type defined - if provided, outletregion_cnt will be assumed to lie at the cuboid face perpendicular to outletregion_nrm pointing toward removal region.
  • OUTREG_CUBOID and no extension type defined - if not provided, outletregion_cnt will be assumed to lie at the center of cuboid.
  • OUTREG_CUBOID and setacc/setvel defined – then the normal definition is mandatory.
  
outletregion_cylinder_rad If OUTREG_CYLINDER is selected as an outlet region type, this command determines the radius of the cylinder. [m]
outletregion_cylinder_hgt If OUTREG_CYLINDER is selected as an outlet region type, this command determines the height of the cylinder (removal region). [m]
outletregion_cuboid_len Side lengths of cuboid removal region in X/Y/Z. [m]
outletregion_tss_file Name of the time state series file containing time (column 1) and state (velocity or acceleration) signed magnitude (column 2) data.
Attention: The second column must be a positive value for velocity, but may be any number for acceleration.
  
outletregion_tss_offset Provided that the TSS file is used for the outlet extension region, this value offsets the beginning of the TSS file in time.
Tip: 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.
 [s]
outletregion_tss_latch Assuming that TSS file for the outlet extension region is provided, this command extends the last specified value in the TSS file until the end of the simulation.
Tip: For example, TSS file specifies the magnitude of 5 m/s at 2 seconds and that is the last entry in the TSS file. Total specified simulation duration is five seconds (t_end = 5). 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.
  
outletregion_time_start Time at which the outlet region becomes active. [s]
outletregion_time_end Time at which the outlet region becomes inactive. [s]
outletregion_time_rampup Time during which the outlet extension velocity/acceleration value goes from zero to the specified peak value. [s]
outletregion_time_rampdn Time during which the outlet extension velocity/acceleration value goes down from a specified peak value to zero. [s]