### 15.1.2. Global Settings and Fluid Settings Tabs

When a simulation involves only one fluid, the Fluid Settings tab is not available, but then all of its contents are added to the Global Settings tab.

#### 15.1.2.1. Coordinate Frame Check Box

This check box determines whether or not a specified coordinate frame is used for interpreting initial conditions. If the check box is not selected, the default coordinate frame, `Coord 0`, is used.

##### 15.1.2.1.1. Coordinate Frame Check Box: Coordinate Frame

Select a coordinate frame to use for interpreting initial conditions. For details, see:

- Coordinate Frames

- Coordinate Frames in the CFX-Solver Modeling Guide

- Coordinate Frame in the CFX-Solver Modeling Guide

#### 15.1.2.2. Frame Type Check Box

This check box determines whether or not a specified frame type is used for interpreting initial values of velocity. If the check box is not selected, the default frame of reference is used. The default frame of reference is stationary or rotating, depending on whether the domain is stationary or rotating, respectively.

##### 15.1.2.2.1. Frame Type

- `Stationary`

  The frame of reference used to interpret initial values of velocity is the stationary frame of reference. For example, if the initial velocity throughout a domain is parallel to the rotation axis of the domain, the flow will initially have no swirl in the stationary frame of reference, even if the domain is rotating.

- `Rotating`

  The frame of reference used to interpret initial values of velocity is that of the associated domain. For example, if the initial velocity throughout a domain is specified as being parallel to the rotation axis of the domain, and if the domain is rotating, the flow will have swirl in the stationary frame of reference.

For details, see Frame Type in the CFX-Solver Modeling Guide.

#### 15.1.2.3. Initial Conditions: Velocity Type

- `Cartesian`

- `Cylindrical`

For details, see Velocity Type in the CFX-Solver Modeling Guide.

#### 15.1.2.4. Initial Conditions: Cartesian Velocity Components

##### 15.1.2.4.1. Option

- `Automatic`

  The initial velocity field is loaded from an initial values file, if one is available. If an initial values file is not available, the initial velocity field is computed from built-in algorithms. For details, see Automatic in the CFX-Solver Modeling Guide.

- `Automatic with Value`

  The initial velocity field is loaded from an initial values file, if one is available. If an initial values file is not available, the initial velocity field is set to user-specified values. For details, see Automatic with Value in the CFX-Solver Modeling Guide.

##### 15.1.2.4.2. Velocity Scale Check Box

(applies only when Option is set to `Automatic`)

This check box determines whether or not a specified velocity scale is used. If the check box is not selected, a velocity scale will be calculated internally by the CFX-Solver, based on a weighted average value of velocity over all applicable Boundary Conditions (inlets, openings and outlets). Initial guess values that are calculated based on the internally calculated velocity scale may be unsuitable due to the shape of your domain, or, for example, due to a small, high-speed inlet which results in an over-prediction of the velocity magnitude.

###### 15.1.2.4.2.1. Velocity Scale Check Box: Value

Enter a numerical quantity or CEL expression for the velocity scale. This is not a normalized value; it is essentially the velocity magnitude that will be used for all applicable velocity vectors. For details, see Velocity Scale in the CFX-Solver Modeling Guide.

##### 15.1.2.4.3. U, V, W

(applies only when Option is set to `Automatic with Value`)

Enter a numerical quantity or CEL expression for each Cartesian velocity component. For details, see Cartesian Velocity Components in the CFX-Solver Modeling Guide.

#### 15.1.2.5. Initial Conditions: Cylindrical Velocity Components

##### 15.1.2.5.1. Option

For details, see Option.

##### 15.1.2.5.2. Velocity Scale Check Box

(applies only when Option is set to `Automatic`)

For details, see Velocity Scale Check Box.

##### 15.1.2.5.3. Axial Component, Radial Component, Theta Component

(applies only when Option is set to `Automatic with Value`)

Enter a numerical quantity or CEL expression for each cylindrical velocity component. For details, see Cylindrical Velocity Components in the CFX-Solver Modeling Guide.

#### 15.1.2.6. Initial Conditions: Static Pressure

##### 15.1.2.6.1. Option

- `Automatic`

  The initial static pressure field is loaded from an initial values file, if one is available. If an initial values file is not available, the initial static pressure field is computed from built-in algorithms.

- `Automatic with Value`

  The initial static pressure field is loaded from an initial values file, if one is available. If an initial values file is not available, the initial static pressure field is set to user-specified values.

For details, see Static Pressure in the CFX-Solver Modeling Guide.

##### 15.1.2.6.2. Relative Pressure

(applies only when Option is set to `Automatic with Value`)

Enter a numerical quantity or CEL expression for the relative pressure.

For details, see Static Pressure in the CFX-Solver Modeling Guide.

#### 15.1.2.7. Initial Conditions: Turbulence

From Option, the various initial condition settings for turbulence are:

- `Low Intensity and Eddy Viscosity Ratio`: This sets intensity to 1% and viscosity ratio to 1.

- `Medium Intensity and Eddy Viscosity Ratio`: This sets intensity to 5% and viscosity ratio to 10.

- `High Intensity and Eddy Viscosity Ratio`: This sets intensity to 10% and viscosity ratio to 100.

- `Intensity and Eddy Viscosity Ratio`: Use this option to specify fractional intensity and eddy viscosity ratio.

- `Intensity and Length Scale`: Use this option to specify fractional intensity and length scale.

- `k and Epsilon`: Use this option to specify turbulence kinetic energy and turbulence eddy dissipation.

- `k and Omega`: Use this option to specify turbulence kinetic energy and turbulence eddy frequency.

- `k and Eddy Viscosity Ratio`: Use this option to specify turbulence kinetic energy and eddy viscosity ratio.

- `k and Length Scale`: Use this option to specify turbulence kinetic energy and length scale.

- `Reynolds Stresses and Epsilon`: Use this option to specify Reynolds Stresses and turbulence eddy dissipation.

- `Reynolds Stresses and Omega`: Use this option to specify Reynolds Stresses and turbulence eddy frequency.

- `Reynolds Stresses and Eddy Viscosity Ratio`: Use this option to specify Reynolds Stresses and eddy viscosity ratio.

- `Reynolds Stresses and Length Scale`: Use this option to specify Reynolds Stresses and length scale.

For additional details, see K (Turbulent Kinetic Energy), Epsilon (Turbulence Eddy Dissipation), and Reynolds Stress Components in the CFX-Solver Modeling Guide.

##### 15.1.2.7.1. Fractional Intensity

- Option: `Automatic`

  The fractional intensity field is loaded from an initial values file, if one is available. If an initial values file is not available, the fractional intensity field is computed automatically.

- Option: `Automatic with Value`

  The fractional intensity field is loaded from an initial values file, if one is available. If an initial values file is not available, the fractional intensity field is set to user-specified values.

##### 15.1.2.7.2. Eddy Viscosity Ratio

- Option: `Automatic`

  The eddy viscosity ratio field is loaded from an initial values file, if one is available. If an initial values file is not available, the eddy viscosity ratio field is computed automatically.

- Option: `Automatic with Value`

  The eddy viscosity ratio field is loaded from an initial values file, if one is available. If an initial values file is not available, the eddy viscosity ratio field is set to user-specified values.

##### 15.1.2.7.3. Eddy Length Scale

- Option: `Automatic`

  The eddy length scale field is loaded from an initial values file, if one is available. If an initial values file is not available, the eddy length scale field is computed automatically.

- Option: `Automatic with Value`

  The eddy length scale field is loaded from an initial values file, if one is available. If an initial values file is not available, the eddy length scale field is set to user-specified values.

##### 15.1.2.7.4. Turbulence Kinetic Energy

- Option: `Automatic`

  The turbulence kinetic energy field is loaded from an initial values file, if one is available. If an initial values file is not available, the turbulence kinetic energy field is computed automatically.

- Option: `Automatic with Value`

  The turbulence kinetic energy field is loaded from an initial values file, if one is available. If an initial values file is not available, the turbulence kinetic energy field is set to user-specified values.

##### 15.1.2.7.5. Turbulence Eddy Dissipation

- Option: `Automatic`

  The turbulence eddy dissipation field is loaded from an initial values file, if one is available. If an initial values file is not available, the turbulence eddy dissipation field is computed automatically.

- Option: `Automatic with Value`

  The turbulence eddy dissipation field is loaded from an initial values file, if one is available. If an initial values file is not available, the turbulence eddy dissipation field is set to user-specified values.

##### 15.1.2.7.6. Turbulence Eddy Frequency

- Option: `Automatic`

  The turbulence eddy frequency field is loaded from an initial values file, if one is available. If an initial values file is not available, the turbulence eddy frequency field is computed automatically.

- Option: `Automatic with Value`

  The turbulence eddy frequency field is loaded from an initial values file, if one is available. If an initial values file is not available, the turbulence eddy frequency field is set to user-specified values.

##### 15.1.2.7.7. Reynolds Stress Components

- Option: `Automatic`

  The Reynolds stress components fields are loaded from an initial values file, if one is available. If an initial values file is not available, the Reynolds stress components fields are computed automatically.

- Option: `Automatic with Value`

  The Reynolds stress components fields are loaded from an initial values file, if one is available. If an initial values file is not available, the Reynolds stress components fields are set to user-specified values.

#### 15.1.2.8. Initial Conditions: Temperature

(applies only when heat transfer is active)

- `Automatic`

  The initial temperature field is loaded from an initial values file, if one is available. If an initial values file is not available, the initial temperature field is computed from built-in algorithms.

- `Automatic with Value`

  The initial temperature field is loaded from an initial values file, if one is available. If an initial values file is not available, the initial temperature field is set to user-specified values.

#### 15.1.2.9. Initial Conditions: Radiation Intensity

(applies only when using the `P1`, `Discrete Transfer`, or `Monte Carlo` model for Thermal Radiation)

##### 15.1.2.9.1. Option

- `Automatic`

  The initial radiation intensity field and blackbody temperature field are loaded from an initial values file, if one is available. If an initial values file is not available, the initial radiation intensity field and blackbody temperature field are computed from built-in algorithms.

- `Automatic with Value`

  The initial radiation intensity field and blackbody temperature field are loaded from an initial values file, if one is available. If an initial values file is not available, the initial radiation intensity field and blackbody temperature field are set to user-specified values.

For details, see Radiation Intensity in the CFX-Solver Modeling Guide.

#### 15.1.2.10. Initial Conditions: Mixture Fraction

##### 15.1.2.10.1. Option

- `Automatic`

  The initial mixture fraction field is loaded from an initial values file, if one is available. If an initial values file is not available, the initial mixture fraction field is computed from built-in algorithms.

- `Automatic with Value`

  The initial mixture fraction field is loaded from an initial values file, if one is available. If an initial values file is not available, the initial mixture fraction field is set to user-specified values.

##### 15.1.2.10.2. Mixture Fraction

Enter a numerical quantity or CEL expression that specifies the value of the mixture fraction throughout the domain.

#### 15.1.2.11. Initial Conditions: Mixture Fraction Variance

##### 15.1.2.11.1. Option

- `Automatic`

  The initial mixture fraction variance field is loaded from an initial values file if, one is available. If an initial values file is not available, the initial mixture fraction variance field is computed from built-in algorithms.

- `Automatic with Value`

  The initial mixture fraction variance field is loaded from an initial values file, if one is available. If an initial values file is not available, the initial mixture fraction variance field is set to user-specified values.

##### 15.1.2.11.2. Mix. Fracn. Variance

Enter a numerical quantity or CEL expression that specifies the value of the mixture fraction variance throughout the domain.

#### 15.1.2.12. Initial Conditions: Component Details

(applies only when the relevant fluid is a variable composition mixture)

##### 15.1.2.12.1. List Box

This list box is used to select a component (of a fluid that is a variable composition mixture) in order to set its fluid-specific initialization options.

##### 15.1.2.12.2. [component name]: Option

- `Automatic`

  The initial mass fraction field is loaded from an initial values file, if one is available. If an initial values file is not available, the initial mass fraction field is computed from built-in algorithms.

- `Automatic with Value`

  The initial mass fraction field is loaded from an initial values file, if one is available. If an initial values file is not available, the initial mass fraction field is set to user-specified values.

##### 15.1.2.12.3. [component name]: Mass Fraction

Available when Option is set to `Automatic with Value`, you must enter a numerical quantity or CEL expression that specifies the value of the component mass fraction throughout the domain.

#### 15.1.2.13. Initial Conditions: Additional Variable Details

This section is similar to Component Details, dealing with Additional Variables instead. For details, see Initial Conditions: Component Details.

#### 15.1.2.14. Fluid Specific Initialization

(applies only when multiple fluids are involved)

The fluid-specific initialization settings are grouped together, either in the Fluid Specific Initialization section or, in the case of global initialization, on the Fluid Settings tab.

#### 15.1.2.15. Fluid Specific Initialization: List Box

This list box is used to select a fluid in order to set its fluid-specific initialization options.

#### 15.1.2.16. Fluid Specific Initialization: [fluid name] Check Box

This check box determines whether or not the initialization options for the indicated fluid are specified explicitly or are left at default values.

#### 15.1.2.17. Fluid Specific Initialization: [fluid name] Check Box: Initial Conditions

Most of the fluid-specific initial condition settings are described in this section as they appear in the non-fluid specific initial condition section in the case of a single-fluid simulation. Those that are not are described here.

##### 15.1.2.17.1. Velocity Type

The velocity type can be either `Cartesian` or `Cylindrical`. For details, see Velocity Type in the CFX-Solver Modeling Guide.

##### 15.1.2.17.2. Volume Fraction: Option

- `Automatic`

  The initial volume fraction field is loaded from an initial values file, if one is available. If an initial values file is not available, the initial volume fraction field is computed from built-in algorithms.

- `Automatic with Value`

  The initial volume fraction field is loaded from an initial values file if one is available. If an initial values file is not available, the initial volume fraction field is set to user-specified values.

##### 15.1.2.17.3. Volume Fraction: Volume Fraction

Enter a numerical quantity or CEL expression that specifies the value of the volume fraction throughout the domain. For details, see Initial Conditions for a Multiphase Simulation in the CFX-Solver Modeling Guide.

#### 15.1.2.18. Solid Specific Initialization

(applies only when there are solids in porous domains)

The solid-specific initialization settings are grouped together, either in the Solid Specific Initialization section or, in the case of global initialization, on the Solid Settings tab.

#### 15.1.2.19. Solid Specific Initialization: List Box

This list box is used to select a solid in order to set its solid-specific initialization options.

#### 15.1.2.20. Solid Specific Initialization: [solid name] Check Box

This check box determines whether or not the initialization options for the indicated solid are specified explicitly or are left at default values.

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