Wind-US User's Guide - Keyword Reference, ARBITRARY INFLOW

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ARBITRARY INFLOW - Arbitrary inflow (block)

Structured Grids

{ARBITRARY INFLOW | DIFFUSER INFLOW} [STATIC | TOTAL] [HOLD_TOTALS | HOLD_CHARACTERISTICS] [DIRECTION {SPECIFIED | CYLINDRICAL | NORMAL [TO INFLOW PLANE] | \ ALONG [GRID LINES]}] ZONE n [UNIFORM [M P T α β [val_k [val_om]]] [sp₁ sp₂ ... sp_n]] [IJK_RANGE [FROZEN] imin imax jmin jmax kmin kmax M P T α β \ [val_k [val_om]] [sp₁ sp₂ ... sp_n]] [XYZ_RANGE [BLEND {XMIN | XMAX}] xmin xmax ymin ymax zmin zmax \ M P T α β [val_k [val_om]] [sp₁ sp₂ ... sp_n]] [RTZ_RANGE [BLEND {ZMIN | ZMAX}] rmin rmax tmin tmax zmin zmax \ M P T α β [val_k [val_om]] [sp₁ sp₂ ... sp_n]] [UNSTEADY var_name freq ampl phase] [TURBULENT [INFLOW] [MAGNITUDE] vpmag {FPS|MEAN|PERCENT} [SIZE nsiz] \ [SEED seed] [PEAK_K kpeak [PER_FOOT]] [BL_HEIGHT blhgt]] [{VORTEX | SOLIDBODY | ROTATESOLID} M_n P T α β xc yc zc \ {dw1 | dw1 dw2 dw3}] [USERSPEC fs bl1 bl2 npts y1 M P T α β y2 M P T α β ... yn M P T α β] [USERCHEM fs bl1 bl2 npts y1 M P T α β sp₁ sp₂ ... sp_n y2 M P T α β sp₁ sp₂ ... sp_n ... yn M P T α β sp₁ sp₂ ... sp_n] [USERKE fs bl1 bl2 npts y1 M P T α β val_k [val_om] y2 M P T α β val_k [val_om] ... yn M P T α β val_k [val_om]] [USERCHEMKE fs bl1 bl2 npts y1 M P T α β sp₁ sp₂ ... sp_n val_k [val_om] y2 M P T α β sp₁ sp₂ ... sp_n val_k [val_om] ... yn M P T α β sp₁ sp₂ ... sp_n val_k [val_om]] [ENDINFLOW]

Unstructured Grids

{ARBITRARY INFLOW | DIFFUSER INFLOW} [STATIC | TOTAL] [HOLD_TOTALS] [DIRECTION {SPECIFIED | CYLINDRICAL | NORMAL [TO INFLOW PLANE]}] ZONE n [UNIFORM [M P T α β]] [sp₁ sp₂ ... sp_n]] [USURFACE {[FROZEN] surface M P T α β [sp₁ sp₂ ... sp_n] | \ MASS surface mass area Ttotal α β}] [XYZ_RANGE [BLEND {XMIN | XMAX}] xmin xmax ymin ymax zmin zmax \ M P T α β [val_k [val_om]] [sp₁ sp₂ ... sp_n]] [RTZ_RANGE [BLEND {ZMIN | ZMAX}] rmin rmax tmin tmax zmin zmax \ M P T α β [val_k [val_om]] [sp₁ sp₂ ... sp_n]] [ENDINFLOW]

Several options are available to set conditions at arbitrary inflow boundaries. The default is uniform inflow (i.e., no boundary layer) at the conditions that are set using the FREESTREAM keyword. Other options are selected by using either of the equivalent keywords ARBITRARY INFLOW or DIFFUSER INFLOW.

The remaining lines select the specific type of inflow data to be provided. Discussion of the input data for each of these options is grouped into sections labeled "Control Functions", "Condition Specification", and "Special Capabilities". These keywords can start in any column. Generally, they should be indented from the ARBITRARY INFLOW keyword to set them apart.

This keyword may also be used to initialize (or reinitialize) the flow conditions within the specified zone, as described in the section Flowfield Initialization.

Note: The GAS keyword and the CHEMISTRY keyword block, if used, must come before the ARBITRARY INFLOW keyword block in the input data (.dat) file.

Structured Grids

Control Functions

ENDINFLOW

This optional keyword may be used to end the arbitrary inflow definition.

STATIC | TOTAL

Arbitrary inflow conditions specified after this keyword will be considered as static or total, depending which of these is set. By default, the flag is set to the value from the FREESTREAM keyword.

When TOTAL is specified, the static conditions are computed using formulas for perfect gases. If total conditions must be specified for real gas flows, the GAS keyword should be used to specify a value for the specific heat ratio γ that is consistent with the real gas mixture being used.

HOLD_TOTALS | HOLD_CHARACTERISTICS

HOLD_TOTALS indicates that total temperature and local flow angles are to be held constant. HOLD_CHARACTERISTICS indicates that characteristic values are to be held constant. The option specified will be applied at all the arbitrary inflow regions in the zone, and will remain in effect for all following ZONE keywords.

The default for structured grids is to hold characteristic values constant.

These keywords only work in conjunction with the UNIFORM, IJK_RANGE, VORTEX, SOLIDBODY, and ROTATESOLID keywords.

The total pressure is always held fixed, whether HOLD_TOTALS is specified or not. Although the Mach number is specified with the UNIFORM and IJK_RANGE keyword parameters, it may be adjusted during the boundary condition treatment.

Note that the HOLD_TOTALS keyword in the ARBITRARY INFLOW keyword block applies to arbitrary inflow boundaries only. See the HOLD keyword for information on holding conditions at freestream boundaries with inflow.

Note also that the syntax is slightly different for arbitrary inflow and freestream boundaries. For arbitrary inflow boundaries, HOLD_TOTALS and HOLD_CHARACTERISTICS are used in the ARBITRARY INFLOW keyword block, with an underscore. For freestream boundaries, HOLD TOTALS and HOLD CHARACTERISTICS are used, without an underscore.

DIRECTION {SPECIFIED | CYLINDRICAL | NORMAL [TO INFLOW PLANE] | ALONG [GRID LINES]}

The DIRECTION keyword indicates how the flow angle is to be set at an inflow plane. The options for setting the flow direction are:

SPECIFIED Set the flow at the angles of attack and yaw specified elsewhere in the ARBITRARY INFLOW block. This is the default.
CYLINDRICAL This is the same as SPECIFIED, except that the angles are in cylindrical coordinates. I.e.,

α = tan⁻¹ (v_θ / v_z )
β = tan⁻¹ (v_r / v_z )
Note that the cylindrical z axis is assumed to be the same as the Cartesian x axis.
NORMAL Set the flow normal to the inflow plane.
ALONG Set the flow in the direction of the grid lines intersecting the inflow plane.

Specifying DIRECTION NORMAL or DIRECTION ALONG will override any angles of attack or yaw specified with the UNIFORM, IJK_RANGE, VORTEX, SOLIDBODY, and ROTATESOLID keywords. However, if UNIFORM is used without specifying the flow conditions, the angles specified with the FREESTREAM keyword will be used, and the DIRECTION keyword will have no effect. The DIRECTION keyword also does not affect flow angles in profiles specified with the USERSPEC, USERCHEM, USERKE, or USERCHEMKE keywords.

The DIRECTION keyword will not modify the flow angles that are set when ARBITRARY INFLOW is being used to initialize (or reinitialize) flow conditions within a zone.

The DIRECTION option used will remain in effect for all following ZONE keywords.

ZONE n

This keyword, which must be specified, identifies the zone for which inflow conditions are being set. For example, if zone 2 is an internal jet, conditions other than freestream may be desired at the inflow to zone 2.

Within the ARBITRARY INFLOW keyword block, the ZONE keyword must come before any "Condition Specification" keyword for that zone, but after any HOLD_TOTALS, HOLD_CHARACTERISTICS, or DIRECTION keyword for that zone. In addition, inflow conditions may only be specified for one zone at a time.

Example

The following ARBITRARY INFLOW block specifies that total conditions are to be held constant at arbitrary inflow surfaces in zones 1 and 2, with M = 3.5, P_T = 251.15 psi, and T_T = 1167.9 °R. In zone 3, characteristic values are to be held constant at arbitrary inflow surfaces, consistent with the flow conditions given with the FREESTREAM keyword.

   ARBITRARY INFLOW 
      TOTAL
      HOLD_TOTALS
         ZONE 1
         UNIFORM 2.5 251.15 1167.9 0.0 0.0
         ZONE 2
         UNIFORM 2.5 251.15 1167.9 0.0 0.0
      HOLD_CHARACTERISTICS
         ZONE 3
         UNIFORM
   ENDINFLOW

Condition Specification

UNIFORM [M P T α β [val_k [val_om]]] [sp₁ sp₂ ... sp_n]

This keyword is used to specify uniform flow at arbitrary inflow boundaries, at the flow conditions listed below. If the flow conditions are omitted, those specified with the FREESTREAM keyword are used.

M Mach number
P Pressure, psi
T Temperature, °R
α, β Angles of attack and yaw, relative to the Cartesian x direction, in degrees
sp₁, sp₂, ..., sp_n Species mass fractions. These are required for real gas flows. The order for these values must be consistent with the order in which the species are listed with the SPECIES keyword in the CHEMISTRY keyword block.

Pressure and temperature are static or total, depending on whether STATIC or TOTAL is specified.

For structured grids, when the SST turbulence model is being used (see the TURBULENCE keyword), val_k and val_om may be used to specify inflow turbulence levels. You may specify either val_k, or val_k and val_om, but not val_om by itself. Note that if these values are being specified, the TURBULENCE keyword must come before the ARBITRARY INFLOW keyword block in the input data (.dat) file.

The following options are possible:

val_k > 0 The turbulent kinetic energy k and the specific dissipation rate ω are specified directly, with

k = val_k (ft²/sec²)
ω = val_om (1/sec)
The turbulent viscosity ν_t is then equal to k/ω.

val_k < 0 The turbulence intensity is set equal to abs(val_k), expressed as a percentage of the inflow velocity U, where U is computed from the specified values of M and T. Thus, the turbulent kinetic energy is computed as

k = 1.5 (0.01 abs(val_k) U)²
The turbulent viscosity ν_t is automatically set equal to 0.001 ν_l, where ν_l is the laminar viscosity, and the specific dissipation rate is computed as ω = k/ν_t.

val_om < 0 The specific dissipation rate ω is set equal to val_om percent of U/L_ref, where U is computed from the specified values of M and T, and L_ref is the reference length from the grid (.cgd) file. Thus

ω = 0.01 abs(val_om) (U/L_ref)
The turbulent viscosity ν_t is set to the same percentage of the laminar viscosity.

ν_t = 0.01 abs(val_om) (ν_l)
The turbulent kinetic energy is then computed as k = ων_t.

If inflow turbulence levels are not specified using one of the above options, or if val_k = 0, default values are computed from

ω = 10 U/L_ref
ν_t = 0.001 ν_l
k = ων_t

Note that

If val_k > 0, a positive value must be specified for val_om.
If val_k ≤ 0, val_om should not be specified.
If val_om < 0, a value must also be specified for val_k, but it is ignored.

Example

   ARBITRARY INFLOW 
      UNIFORM 1.1 100. 900. 10. 0.
   ENDINFLOW

IJK_RANGE [FROZEN] imin imax jmin jmax kmin kmax M P T α β \ [val_k [val_om]] [sp₁ sp₂ ... sp_n]

For structured grids, this keyword allows specification of inflow conditions over an arbitrary range of i, j, and k indices on any computational boundary plane. The user specifies the minimum and maximum i, j, and k indices which describe the region, followed by the flow conditions to be applied, as follows:

imin, imax Minimum and maximum i indices bounding the region
jmin, jmax Minimum and maximum j indices bounding the region
kmin, kmax Minimum and maximum k indices bounding the region
M Mach number
P Pressure, psi
T Temperature, °R
α, β Angles of attack and yaw, relative to the Cartesian x direction, in degrees
sp₁, sp₂, ..., sp_n Species mass fractions. These are required for real gas flows. The order for these values must be consistent with the order in which the species are listed with the SPECIES keyword in the CHEMISTRY keyword block.

Pressure and temperature are static or total, depending on whether STATIC or TOTAL is specified. There are no defaults for the index ranges.

The FROZEN option may be specified to freeze the inflow conditions over the indicated index range at their current values. Note that for a restart case (i.e., when a .cfl file already exists), the "current values" are those in the .cfl file, not those specified with the IJK_RANGE keyword. For an initial run (i.e., when a .cfl file does not exist), the flow conditions will be frozen at the conditions specified with the IJK_RANGE keyword.

If the SST turbulence model is being used (see the TURBULENCE keyword), val_k and val_om may be used to specify inflow turbulence levels. The various options are described above under the UNIFORM keyword.

A combination of up to 500 IJK_RANGE, XYZ_RANGE, and RTZ_RANGE regions and (for unstructured grids) USURFACE surfaces may be specified. This is useful when specifying a boundary layer profile at an inflow boundary, or along solid walls during the flowfield initialization process.

XYZ_RANGE [BLEND {XMIN | XMAX}] xmin xmax ymin ymax zmin zmax \ M P T α β [val_k [val_om]] [sp₁ sp₂ ... sp_n]

This keyword is intended for use during the flowfield initialization process, and allows specification of initial conditions in a specified Cartesian bounding box. The user specifies the bounding box coordinates, followed by the flow conditions to be applied, as follows:

xmin, xmax x_min and x_max coordinates of bounding box
ymin, ymax y_min and y_max coordinates of bounding box
zmin, zmax z_min and z_max coordinates of bounding box
M Mach number
P Pressure, psi
T Temperature, °R
α, β Angles of attack and yaw, relative to the Cartesian x direction, in degrees
sp₁, sp₂, ..., sp_n Species mass fractions. These are required for real gas flows. The order for these values must be consistent with the order in which the species are listed with the SPECIES keyword in the CHEMISTRY keyword block.

Pressure and temperature are static or total, depending on whether STATIC or TOTAL is specified. There are no defaults for the bounding box coordinates.

If BLEND XMIN or BLEND XMAX is specified, the initial conditions will smoothly transition from the specified values at x_min to freestream values at x_max, or from the specified values at x_max to freestream values at x_min, respectively. If BLEND is not specified, the initial conditions will be uniform, at the specified values. This option is only available for perfect gas flows.

RTZ_RANGE [BLEND {ZMIN | ZMAX}] rmin rmax tmin tmax zmin zmax \ M P T α β [val_k [val_om]] [sp₁ sp₂ ... sp_n]

This keyword is analogous to the XYZ_RANGE keyword, but allows the bounding box to be specified in cylindrical coordinates. It's assumed that the cylindrical z axis is the same as the Cartesian x axis. The bounding box coordinates are:

rmin, rmax r_min and r_max coordinates of bounding box
tmin, tmax θ_min and θ_max coordinates of bounding box
zmin, zmax z_min and z_max coordinates of bounding box

The remaining input is the same as for XYZ_RANGE.

If BLEND ZMIN or BLEND ZMAX is specified, the initial conditions will smoothly transition from the specified values at z_min to freestream values at z_max, or from the specified values at z_max to freestream values at z_min, respectively. If BLEND is not specified, the initial conditions will be uniform, at the specified values.

UNSTEADY var_name freq ampl phase

For structured grids, this keyword allows the user to specify unsteady arbitrary inflow conditions. It must be used with (and follow) the IJK_RANGE keyword. Up to ten different perturbations to the inflow conditions may be specified and will be superimposed to create unsteadiness centered about the conditions given with the IJK_RANGE keyword.

var_name One of the keywords MACH, PRESSURE, TEMPERATURE, ALPHA, BETA, or VELOCITY
freq Frequency of the perturbation in Hertz
ampl Amplitude of the perturbation in appropriate variable units
phase Phase angle of the perturbation in degrees

Note that you may specify multiple, independent pairs of IJK_RANGE and UNSTEADY keywords.

TURBULENT [INFLOW] [MAGNITUDE] vpmag {FPS|MEAN|PERCENT} [SIZE nsiz] \ [SEED seed] [PEAK_K kpeak [PER_FOOT]] [BL_HEIGHT blhgt]

For structured grids, this keyword allows the user to specify an unsteady pseudo-turbulent flow at the inflow boundary. It currently only affects the boundary conditions for the mean flow, not the turbulence model equations. Since the mean velocity field typically carries the majority of the energy, this isn't considered critical.

vpmag Magnitude of the turbulent intensity (i.e., turbulent velocity fluctuations) specified in either feet per second (FPS), fraction of the mean flow velocity (MEAN), or percent of the mean flow velocity (PERCENT). The intensity will be the same in each coordinate direction.
nsiz Number of grid points on each side of the "box" of pseudo-turbulent inflow. I.e., the box will contain nsiz × nsiz points for 2-D cases, and nsiz × nsiz × nsiz points for 3-D cases. The default value is 64.
seed A random number seed, used to ensure repeatability of a given run. The default value is 987.0.
kpeak The wave number (based on the box size unless PER_FOOT is specified) where the energy spectrum is to peak. The default value is 8.0.
blhgt The height, in feet, of the incoming boundary layer. The turbulence at the inflow boundary will be scaled in this region to account for the presence of the boundary layer. The default is L_box/10, where L_box is the length of a side of the cube bounding the arbitrary inflow boundary.

When the TURBULENT keyword is used, total conditions must be held constant, and HOLD_TOTALS is automatically applied.

{VORTEX | SOLIDBODY | ROTATESOLID} M_n P T α β xc yc zc \ {dw1 | dw1 dw2 dw3}

For structured grids, these keywords may be used to specify uniform inflow conditions with free-vortex or solid-body rotation superimposed. They are only valid for a perfect gas, and cannot be used with CHEMISTRY. Solid-body rotation may be specified on any arbitrary inflow boundary. For free-vortex rotation, however, the arbitrary inflow boundary must be a constant x, y, or z plane, and the center of rotation must lie on that plane.

M_n Normal component of Mach number
P Pressure, psi
T Temperature, °R
α, β Average angles of attack and yaw, relative to the Cartesian x direction, in degrees
xc, yc, zc Center of rotation in physical coordinates

For VORTEX,

dw1 Vortex strength. (See the ACTUATOR keyword.)

For SOLIDBODY and ROTATESOLID,

dw1, dw2, dw3 x, y, and z components of the rotation rate vector (degrees/sec). (Note: prior to Wind-US 2.184 these were in radians per second. Input data files using these keywords with earlier versions of Wind-US will need to be changed if used with Wind-US 2.184 or later.)

The rotational velocity components are added in such a way that total pressure and total temperature are held constant at the inflow boundary. Thus, the TOTAL option should always be used for this mode, since with the STATIC option the computed static pressure and temperature at the inflow boundary may differ from the specified values.

For calculations in a rotating reference frame (see the ROTATE keyword):

If the SOLIDBODY option is used, the total conditions specified are those in the rotating frame, and are held fixed in that frame. The total conditions in the inertial frame will vary.
If the ROTATESOLID option is used, the total conditions specified are those in the inertial frame, and are held fixed in that frame. The total conditions in the rotating frame will vary. Note that the ROTATESOLID option is only valid for calculations in a rotating reference frame.

For both free-vortex and solid-body rotation, the flowfield must already be initialized. (See the Flowfield Initialization section.) I.e., there must be a pre-existing .cfl file. The VORTEX, SOLIDBODY, and ROTATESOLID options cannot be used during a "cold" start.

Special Capabilities

The following arbitrary inflow keywords are only valid for structured grids, and are only applied at the i = 1 computational plane.

USERSPEC fs bl1 bl2 npts y1 M P T α β y2 M P T α β ... yn M P T α β

This option allows the user to specify a 1-D profile normal to the surface, translated through some buttline range, below the vehicle. These conditions will be set last and thus the data will overwrite UNIFORM conditions over the range of interest.

fs Fuselage station of the profile (to be checked against the grid i = 1 fuselage station)
bl1, bl2 Minimum and maximum buttline over which to translate the profile
npts Number of points defining the profile
y1 - yn Normal distance from the wall
M Mach number
P Pressure, psi
T Temperature, °R
α, β Angles of attack and yaw, relative to the Cartesian x direction, in degrees

The pressure and temperature may be the total or static conditions, depending upon the current setting of the TOTAL/STATIC keyword. If neither STATIC nor TOTAL have been specified under ARBITRARY INFLOW, then the existing switch from the global input parameters is used (default: TOTAL).

One profile can be specified for each zone. There can be 100 points in each profile. The normal distance is always assumed to be from j = 1 (the reference wall is assumed to be at j = 1). bl1 is the minimum buttline and bl2 is the maximum buttline.

See Also: TEST 157
By default, USERSPEC only specifies conditions below a vehicle. That is, the wall (j = 1) must be above (higher y) the interior grid points. TEST 157 specifies that all points within the specified buttline range will be affected, above and below the vehicle. This should be the default, but isn't.

USERCHEM fs bl1 bl2 npts y1 M P T α β sp₁ sp₂ ... sp_n y2 M P T α β sp₁ sp₂ ... sp_n ... yn M P T α β sp₁ sp₂ ... sp_n

The USERCHEM option is identical to the USERSPEC option, except that chemistry species mass fractions sp₁, sp₂, ..., sp_n are added. The order for the mass fractions must be consistent with the order in which the species are listed with the SPECIES keyword in the CHEMISTRY keyword block. Test options can then be set to model the mixing of gas streams which have different chemical compositions. At this time, only mixing can be modeled. The gas streams cannot chemically react.

Note: Only the STATIC input mode is available for chemistry.

Part of an example USERCHEM input block follows. The file sets up a rectangular jet where the jet composition is a mixture of O₂, CO₂, H₂O, NO₂, and N₂.

   ARBITRARY INFLOW
      ZONE 1
      USERCHEM 0.0 -10.0 10.0 6
        0.0   0.3  5.70   433.1  0.0  0.0
            0.234  0.0    0.0    0.0  0.766
      123.05  0.3  5.70   433.1  0.0  0.0
            0.234  0.0    0.0    0.0  0.766
      123.05  1.8  5.66  1940.0  0.0  0.0
            0.096  0.120  0.048  0.0  0.736
      133.75  1.8  5.66  1940.0  0.0  0.0
            0.096  0.120  0.048  0.0  0.736
      133.75  0.3  5.70   433.1  0.0  0.0
            0.234  0.0    0.0    0.0  0.766
      257.0   0.3  5.70   433.1  0.0  0.0
            0.234  0.0    0.0    0.0  0.766
   ENDINFLOW
   TEST 157 1     USERSPEC ABOVE AND BELOW VEHICLE

USERKE fs bl1 bl2 npts y1 M P T α β val_k [val_om] y2 M P T α β val_k [val_om] ... yn M P T α β val_k [val_om]

The USERKE option is identical to the USERSPEC option, except that the values val_k and val_om are added to specify inflow turbulence levels when the SST turbulence model is being used. The various options are described above under the UNIFORM keyword.

USERCHEMKE fs bl1 bl2 npts y1 M P T α β sp₁ sp₂ ... sp_n val_k [val_om] y2 M P T α β sp₁ sp₂ ... sp_n val_k [val_om] ... yn M P T α β sp₁ sp₂ ... sp_n val_k [val_om]

The USERCHEMKE option is identical to the USERCHEM option, except that the values val_k and val_om are added to specify inflow turbulence levels when the SST turbulence model is being used. The various options are described above under the UNIFORM keyword.

See Also: EXTRAPOLATE, INITIALIZE, REINITIALIZE, ROTATE, TURBULENCE

Unstructured Grids

Control Functions

ENDINFLOW

This optional keyword may be used to end the arbitrary inflow definition.

STATIC | TOTAL

STATIC may not be used with USURFACE MASS.

With unstructured grids, TOTAL may only be used for an ideal gas.

HOLD_TOTALS

For points with subsonic inflow, specifying HOLD_TOTALS indicates that total temperature, total pressure, and the local flow angles are to be held at their specified values, and the Mach number will be extrapolated. If HOLD_TOTALS is not specified, total temperature, Mach number, and the local flow angles will be held at their specified values, and the total pressure will be extrapolated.

For points with supersonic inflow, all conditions are held at their specified values, whether HOLD_TOTALS is specified or not.

Note that the HOLD_CHARACTERISTICS option is not available for unstructured grids.

For unstructured grids, HOLD_TOTALS is only valid for a perfect gas. The option will be applied at all the arbitrary inflow regions in the zone, and will remain in effect for all following ZONE keywords.

HOLD_TOTALS only works in conjunction with the USURFACE keyword.

DIRECTION {SPECIFIED | CYLINDRICAL | NORMAL [TO INFLOW PLANE]}

The DIRECTION keyword indicates how the flow angle is to be set at an inflow plane. The options and input are the same as described above for the use of the DIRECTION keyword with structured grids, except that the ALONG [GRID LINES] option does not apply to unstructured grids.

ZONE n

Within the ARBITRARY INFLOW keyword block, the ZONE keyword must come before any "Condition Specification" keyword for that zone, but after the HOLD_TOTALS keyword for that zone. In addition, inflow conditions may only be specified for one zone at a time.

Condition Specification

UNIFORM [M P T α β] [sp₁ sp₂ ... sp_n]

Pressure and temperature are static or total, depending on whether STATIC or TOTAL is specified.

USURFACE {[FROZEN] surface M P T α β [sp₁ sp₂ ... sp_n] | \ MASS surface mass area Ttotal α β}

This keyword is used with unstructured grids to specify uniform flow at arbitrary inflow surfaces, at the flow conditions listed below. The flow conditions may be specified in terms of Mach number, pressure, and temperature, or in terms of mass flow rate, area, and total temperature. Note that unlike the UNIFORM keyword, the flow conditions must be specified.

For the first form of the USURFACE keyword, the input is:

surface Surface ID number
M Mach number
P Pressure, psi
T Temperature, °R
α, β Angles of attack and yaw, relative to the Cartesian x direction, in degrees
sp₁, sp₂, ..., sp_n Species mass fractions. These are required for real gas flows. The order for these values must be consistent with the order in which the species are listed with the SPECIES keyword in the CHEMISTRY keyword block. Note that unlike the UNIFORM keyword, here the mass fractions are on the same line as the rest of the flow conditions.

The pressure and temperature listed above may be either static or total, depending on whether STATIC or TOTAL is specified.

The FROZEN option may be specified to freeze the inflow conditions on the surface at the specified values. Note that unlike the FROZEN option available with IJK_RANGE for structured grids, here the values specified with the keyword are used, not those in the .cfl file.

When USURFACE MASS is used, the input is:

surface Surface ID number
mass Mass flow rate, lb_m/sec
area Area, in²
Ttotal Total temperature, °R
α, β These values must be specified, but for USURFACE MASS they are ignored, and the flow will automatically be directed normal to the surface.

Note that when USURFACE MASS is used, the FROZEN option is not available, and total temperature must be specified. Either

TOTAL must be specified in the ARBITRARY INFLOW keyword block, or
TOTAL must be specified with the FREESTREAM keyword, and STATIC|TOTAL omitted in the ARBITRARY INFLOW block

USURFACE MASS may only be used with perfect gases.

The total number of USURFACE surfaces, and IJK_RANGE, XYZ_RANGE, and RTZ_RANGE regions, is limited to 500.

XYZ_RANGE [BLEND {XMIN | XMAX}] xmin xmax ymin ymax zmin zmax \ M P T α β [val_k [val_om]] [sp₁ sp₂ ... sp_n]

This keyword is intended for use during the flowfield initialization process, and allows specification of initial conditions in a specified Cartesian bounding box. The options and input are the same as described above for the use of the XYZ_RANGE keyword with structured grids.

RTZ_RANGE [BLEND {ZMIN | ZMAX}] rmin rmax tmin tmax zmin zmax \ M P T α β [val_k [val_om]] [sp₁ sp₂ ... sp_n]

This keyword is analogous to the XYZ_RANGE keyword, but allows the bounding box to be specified in cylindrical coordinates. The options and input are the same as described above for the use of the RTZ_RANGE keyword with structured grids.

Examples

   ARBITRARY INFLOW 
      USURFACE 9 1.1 100. 900. 10. 0.
   ENDINFLOW

   ARBITRARY INFLOW 
      USURFACE MASS 9 939. 1440. 900. 0. 0.
   ENDINFLOW

	`SPECIFIED`		Set the flow at the angles of attack and yaw specified elsewhere in the `ARBITRARY INFLOW` block. This is the default.
	`CYLINDRICAL`		This is the same as `SPECIFIED`, except that the angles are in cylindrical coordinates. I.e., α = tan⁻¹ (v_θ / v_z ) β = tan⁻¹ (v_r / v_z ) Note that the cylindrical z axis is assumed to be the same as the Cartesian x axis.
	`NORMAL`		Set the flow normal to the inflow plane.
	`ALONG`		Set the flow in the direction of the grid lines intersecting the inflow plane.

	M		Mach number
	P		Pressure, psi
	T		Temperature, °R
	α, β		Angles of attack and yaw, relative to the Cartesian x direction, in degrees
	sp₁, sp₂, ..., sp_n		Species mass fractions. These are required for real gas flows. The order for these values must be consistent with the order in which the species are listed with the `SPECIES` keyword in the `CHEMISTRY` keyword block.

	imin, imax		Minimum and maximum i indices bounding the region
	jmin, jmax		Minimum and maximum j indices bounding the region
	kmin, kmax		Minimum and maximum k indices bounding the region
	M		Mach number
	P		Pressure, psi
	T		Temperature, °R
	α, β		Angles of attack and yaw, relative to the Cartesian x direction, in degrees
	sp₁, sp₂, ..., sp_n		Species mass fractions. These are required for real gas flows. The order for these values must be consistent with the order in which the species are listed with the `SPECIES` keyword in the `CHEMISTRY` keyword block.

	xmin, xmax		x_min and x_max coordinates of bounding box
	ymin, ymax		y_min and y_max coordinates of bounding box
	zmin, zmax		z_min and z_max coordinates of bounding box
	M		Mach number
	P		Pressure, psi
	T		Temperature, °R
	α, β		Angles of attack and yaw, relative to the Cartesian x direction, in degrees
	sp₁, sp₂, ..., sp_n		Species mass fractions. These are required for real gas flows. The order for these values must be consistent with the order in which the species are listed with the `SPECIES` keyword in the `CHEMISTRY` keyword block.

	rmin, rmax		r_min and r_max coordinates of bounding box
	tmin, tmax		θ_min and θ_max coordinates of bounding box
	zmin, zmax		z_min and z_max coordinates of bounding box

	var_name		One of the keywords `MACH`, `PRESSURE`, `TEMPERATURE`, `ALPHA`, `BETA`, or `VELOCITY`
	freq		Frequency of the perturbation in Hertz
	ampl		Amplitude of the perturbation in appropriate variable units
	phase		Phase angle of the perturbation in degrees

	vpmag		Magnitude of the turbulent intensity (i.e., turbulent velocity fluctuations) specified in either feet per second (`FPS`), fraction of the mean flow velocity (`MEAN`), or percent of the mean flow velocity (`PERCENT`). The intensity will be the same in each coordinate direction.
	nsiz		Number of grid points on each side of the "box" of pseudo-turbulent inflow. I.e., the box will contain `nsiz` × `nsiz` points for 2-D cases, and `nsiz` × `nsiz` × `nsiz` points for 3-D cases. The default value is 64.
	seed		A random number seed, used to ensure repeatability of a given run. The default value is 987.0.
	kpeak		The wave number (based on the box size unless `PER_FOOT` is specified) where the energy spectrum is to peak. The default value is 8.0.
	blhgt		The height, in feet, of the incoming boundary layer. The turbulence at the inflow boundary will be scaled in this region to account for the presence of the boundary layer. The default is L_box/10, where L_box is the length of a side of the cube bounding the arbitrary inflow boundary.

	M_n		Normal component of Mach number
	P		Pressure, psi
	T		Temperature, °R
	α, β		Average angles of attack and yaw, relative to the Cartesian x direction, in degrees
	xc, yc, zc		Center of rotation in physical coordinates

	fs		Fuselage station of the profile (to be checked against the grid i = 1 fuselage station)
	bl1, bl2		Minimum and maximum buttline over which to translate the profile
	npts		Number of points defining the profile
	y1 - yn		Normal distance from the wall
	M		Mach number
	P		Pressure, psi
	T		Temperature, °R
	α, β		Angles of attack and yaw, relative to the Cartesian x direction, in degrees

	surface		Surface ID number
	M		Mach number
	P		Pressure, psi
	T		Temperature, °R
	α, β		Angles of attack and yaw, relative to the Cartesian x direction, in degrees
	sp₁, sp₂, ..., sp_n		Species mass fractions. These are required for real gas flows. The order for these values must be consistent with the order in which the species are listed with the `SPECIES` keyword in the `CHEMISTRY` keyword block. Note that unlike the `UNIFORM` keyword, here the mass fractions are on the same line as the rest of the flow conditions.

	surface		Surface ID number
	mass		Mass flow rate, lb_m/sec
	area		Area, in²
	Ttotal		Total temperature, °R
	α, β		These values must be specified, but for `USURFACE MASS` they are ignored, and the flow will automatically be directed normal to the surface.