Inlet
The Inlet node includes a set of boundary conditions describing the fluid flow and temperature conditions at an inlet. The applied conditions are controlled by the Flow Condition.
Flow Condition
Select a Flow condition — Characteristics based (the default), Supersonic or Subsonic.
For Characteristics based 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).
Flow Properties
When the Flow condition is set to Characteristics based or Supersonic, specify the flow properties at the inlet in terms of the static or total pressure, static or total temperature, Mach number, and flow direction. By default Static input variables are used.
Select an Input state — Static (the default) or Total. For either selection also enter values or expressions for the Mach number Ma0 (dimensionless) at the inlet. The default is 1.5.
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For Static enter values or expressions for the Static pressure p0,stat (SI unit: Pa) and Static temperature T0,stat (SI unit: K).
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For Total enter values or expressions for the Total pressure p0,tot (SI unit: Pa) and Total temperature T0,tot (SI unit: K).
The relationships between the static and total states are:
(5-2)
Select a Flow direction — Normal inflow (the default) or User defined to specify an arbitrary flow direction. Then enter the components of the direction normal nM (dimensionless).
When the Flow condition is set to Subsonic, choose to specify either Velocity or Pressure. For Velocity, enter a value or expression for U0 (SI unit: m / s). For Pressure, enter a value or expression for p0 (SI unit: Pa). The Suppress backflow option is enabled by default. Select a Flow direction — Normal inflow (the default) or User defined. Choose to specify either Temperature or Heat flux. For Temperature, enter a value or expression for T0 (SI unit: K). For Heat flux, enter a value or expression for Tustr (SI unit: K).
Turbulence Properties
This section displays when RANS-EVM or RANS-RSM is selected as Turbulence model type.
Turbulence properties at an inlet can be specified according to one of the following options:
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Select Specify turbulence length scale and intensity to enter values or expressions for the Turbulent intensity IT (dimensionless) and Turbulence length scale LT (SI unit: m). IT and LT values are related to the turbulence variables via
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For Specify turbulence variables enter values or expressions for the turbulence variables, such as Turbulent kinetic energy k0 (SI unit: m2/s2), Turbulent dissipation rate, ε0 (SI unit: m2/s3), Specific dissipation rate, ω0 (SI unit: 1/s), Kinematic Reynolds stress tensor R0 (SI unit: m2/s2), Undamped turbulent kinematic viscosity, υ0 (SI unit: m2/s), Turbulent relative fluctuations, ζ0 (dimensionless), Elliptic blending function, α0 (dimensionless) and Intermittency, γ0 (dimensionless) depending on the choice of Turbulence model.
For background on the derivation and implementation of the conditions, see Theory for the High Mach Number Flow Interfaces.
For recommendations of physically sound values see Inlet Values for the Turbulence Length Scale and Turbulent Intensity.