Specify Initial Condition Parameters

Depending on the selected region (fluid or solid), you can specify either an initial flow parameters distribution or initial solid temperature.

The selected region can be changed one of the following way:

in the Component Control dialog box (see “Component Control” for details).
by selecting the Disable solid components option in the Initial Condition dialog.

If you want to specify a coordinate-dependent value, click Dependency to the right of the parameter value input box (see “Dependency” for details).

Procedure

The following parameters can be specified for the selected fluid region:
1. Under Flow Parameters you can specify the initial Velocity vector or Mach Number vector (only for gases) by specifying its components in X Direction, Y Direction and Z Direction with respect to the Coordinate System selected in the Selection group (if the Fluid Flow option is enabled on the Analysis type tab of the General Settings or Wizard dialog).
2. Under Thermodynamic Parameters you can specify initial distributions of the thermodynamic parameters (if the Fluid Flow option is enabled on the Analysis type tab):
  - For liquids you can specify the initial static Pressure and Temperature .
  - For gases you can select a pair of the thermodynamic parameters to specify and the third parameter will be calculated automatically:
    - Pressure, Temperature . Specify the initial static Pressure , Temperature .
    - Pressure, Density . Specify the initial static Pressure , Density .
    - Temperature, Density . Specify the initial static Temperature , Density .
    - If you enable a rotating reference frame (the Rotation option is enabled on the Analysis type tab), you can select the Pressure potential (Rotation) check box to specify the pressure distribution relative to the rotating reference frame.
    - If you enable gravitational effects (the Gravitation option is enabled on the Analysis type tab), you can select the Pressure potential (Gravity) check box to assign the spatial distribution of pressure (see “Pressure Potential for Gravitational Effects”).
3. Under Substance Concentrations (if the Fluid Flow option is enabled on the Analysis type tab and the number of fluids selected as default fluids on the Fluids tab is greater than one), the relative concentrations can be specified either by Mass fractions or Volume fractions.
  - If you model a flow of two immiscible fluids with an interface (if the Free Surface option is enabled on the Analysis type tab), you must define the Initial Fluid distribution by specifying how fluids are distributed throughout the computational domain.
    
    The height is measured from the origin of the reference Coordinate System (see below).
  - If you model a combustion of gas-phase mixtures (if the Combustible mixture is selected as the project’s fluid on the Fluids tab), you can specify initial concentrations of Fuel and Oxidizer by mass fractions only.
4. Under Humidity for project involving calculation of the relative humidity of gas or mixture of gases (if the Fluid Flow option is enabled on the Analysis type tab and the Humidity option is enabled on the Fluids tab), the Relative humidity value can be specified for the gas or mixture of gases within the selected fluid region.
5. Under Turbulence Parameters (if the Fluid Flow option is enabled on the Analysis type tab and the Laminar and turbulent or Turbulent Only flow type is selected on the Fluids tab), you can specify the parameters of turbulence in the initial flow (see “Turbulence” for details).
  The turbulence parameters can be specified in terms of:
  - Turbulence Intensity and Length .Specify the values of Turbulence Intensity and Turbulence Length .
  - Turbulence Energy and Dissipation . Specify the values of Turbulence Energy and Turbulence Dissipation .
Under Solid Parameters for Conjugate Heat Transfer problems (if the Conduction option is enabled on the Analysis Type tab), you can specify the Initial solid temperature for the selected solid components enabled in Component Control (see “Component Control”for details).