M I X I N G L E N G T H L I M I T ( T U R B U L E N T K - E P S I L O N M O D E L S O N L Y )

This section is only available for the k- and Low Re k- turbulent models, which need an upper limit on the mixing length. Select a Mixing length limit—Automatic (the default) or Manual.

• If Automatic is selected, the wall distance is automatically evaluated as:

where d is the dimension of the geometry (for example, three for a 3D geometry) and lbb is the shortest side of the geometry bounding box. If the geometry is a complicated system of very slender entities, for example, Equation 11-1 tends to give a result that is too large. Then define lmixlim manually.

•If Manual is selected, enter a value or expression for the Mixing length limit lmixlim (SI unit: m).

Inlet

The Inlet node includes a set of boundary conditions describing the fluid flow and temperature condition at an inlet. The applied conditions are controlled by the Flow Condition:

•Using a Characteristics Based condition, the current flow situation is analyzed using the inviscid flow characteristics at the inlet. This can be used to specify either a subsonic (Ma < 1) inlet or a supersonic inlet (Ma > 1). This is the default condition.

•Select Supersonic, when the inlet flow is known to be supersonic.

For background of the derivation and implementation of the conditions,

see the Theory for the High Mach Number Interfaces.

See Also

B O U N D A R Y S E L E C T I O N

From the Selection list, choose the boundaries that represent inlets.

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F L O W P R O P E R T I E S

Specify the flow properties, in terms of the pressure, temperature and Mach number, and flow direction, at the inlet. The input of the first to properties are controlled by the Input state:

•By default Static input variables are used. Enter values or expressions for the Static pressure p0,stat (SI unit: Pa) and Static temperature T0,stat (SI unit: K).

•If Total is selected, instead enter values or expressions for the Total pressure p0,tot (SI unit: Pa) and Total temperature T0,tot (SI unit: K).

The relations between these static and total states are:

Also enter values or expressions for the Mach number M0 (unitless) at the inlet.

By default Normal inflow is selected. To specify an arbitrary flow direction, select User defined in the Flow direction list and enter the components of nM (unitless).

T U R B U L E N C E P R O P E R T I E S

This section displays when RANS is selected as Turbulence Model Type.

Note

Using a turbulence model, specify the turbulence properties at an inlet. For the

Turbulent Flow, k- model, specify these options:

•Select Specify turbulence length scale and intensity to enter values or expressions for

the Turbulent intensity IT (unitless) and Turbulence length scale LT (SI unit: m). The Turbulent intensity IT and Turbulence length scale LT values are related to the turbulence variables via

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