Each region Initialization, whether the Default, Cylinder, Port, or a Sub-volume region, requires specification of the following variables:
Temperature
Pressure
Composition of species
Velocity
In addition, if any of the Turbulence Model (See Turbulence) is turned on, turbulence-related variables such as turbulent kinetic energy, should be specified. The same Turbulence specification options are available as described for the Outlet Boundary specification in Outlet Panel.
If the Method of Moments Soot Model (See Soot Model) is turned on and that the surface chemical mechanism contains dispersed-phase materials, you may choose to specify the initial conditions for Surface Composition and Dispersed Phase. This is only required if particles are assumed to be already present at the start of the simulation.
Each of the above-mentioned variables can be specified either as Constant or Spatially Varying. These two different scenarios are explained in the next sections.
This section describes how to set the initial condition of a variable as Constant.
To specify constant initial conditions for the scalar variables such as Temperature, Pressure, and Turbulence, you may simply enter the scalar constant values for these variables.
To specify constant Composition of species: Use the Mixture
Editor 
to specify the details of the constant composition. See Mixture Editor for details.
To specify Surface Composition and Dispersed
Phase parameters: Use the Solid Phase Editor 
to specify the details of the surface composition and dispersed phase
properties (see Solid Phase Editor and Dispersed Phase Editor for Particle Tracking
for details).
The velocity can be specified in absolute values as coordinate components ("Velocity Components"), or using a swirl-flow correlation. The swirl-flow may be defined as general or "engine swirl" and these are provided as two options: Engine Swirl and General Swirl.
The Engine Swirl correlation requires association of a moving wall boundary that has slider-crank motion, since the swirl-flow is scaled with the angular velocity of the crank rotation. For body-fitted cases, this association is done automatically, but for automatic mesh generation, you must select the appropriate boundary (for example, the piston boundary) and make this association explicitly.
The General Swirl correlation does not require a slider-crank motion to provide the reference angular velocity. Instead, you can specify the angular velocity explicitly. The general swirl option is useful for applications in which a slider-crank motion boundary does not exist.
For details of initializing constant velocity field using either Engine Swirl or General Swirl correlations, see Using Swirl Ratio to Initialize Velocity.
As described in the Ansys Forte Theory Manual, a swirl pattern is often induced within the engine cylinder for the initial gas mixture. To specify swirl conditions, you must first select Engine Swirl or General Swirl in the pull-down list next to Velocity on the Initialization Editor panel (Initial Conditions > Initialization). For automatic-mesh generation projects, select the Geometry entity that corresponds to the Boundary condition where a slider-crank wall motion is imposed, such as the piston surface, in the Slider Crank Boundary list if more than one region exists in the mesh.
For the Engine Swirl option, specify the following parameters:
Initial Swirl Ratio: This is the initial ratio of the swirl flow's angular momentum relative to the crankshaft rotation speed (both in revolutions per minute). When viewed from the positive Z direction, a positive value of swirl indicates counterclockwise motion in keeping with the right-hand rule. The rotation is assumed to be about the Z-axis. A default value is provided that is typical for many engines.
Initial Swirl Profile Factor: This factor, referred to as α in the Ansys Forte Theory Manual, is a dimensionless constant that defines the initial azimuthal velocity profile. It should have a value that lies between 0.0 (the wheel flow limit) and 3.83 (corresponding to zero velocity at the wall). The recommended and default value is 3.11.
Initialize Velocity Components Normal to Piston: If checked, the axial velocity component will be set to vary linearly from the piston surface to the top of the region (axial velocity = piston velocity at the piston surface, axial velocity = 0 at top of cylinder) for an engine cylinder.
For General Swirl, specify the Reference Frame (see Reference Frames) and the following parameters:
Radius: The radius defining the outermost swirling velocity location with respect to the Z-axis of the reference frame.
Axial Velocity: The initial axial velocity to be applied uniformly within the region defined by this initialization.
Reference Angular Velocity: The angular velocity defining the swirl velocity.
Initial Swirl Profile Factor: The initial swirl profile factor, α, is a dimensionless constant that defines the initial azimuthal velocity profile and lies between 0.0 (the wheel flow limit) and 3.83 (zero velocity at the wall). The recommended value is 3.11.
This section describes how to set the initial condition of a variable as Spatially Varying.
To specify a spatially varying variable, click the Pencil 
icon next to Create new... and the Initial
Condition (IC) Table Editor launches. Name this new time-varying condition and use
the buttons at the bottom of the window to import data from a structured data file or map
variables from a CGNS-formatted file. For details about how to use the IC Table Editor, refer
to Initial Conditions Table Editor. If you have already
created an IC table that contains the data for this variable, you may simply select its name
and use it here.
Offset and Scaling Factors for the Spatially Varying Option: If the spatially varying option is selected for pressure, temperature, turbulence parameters, or the three velocity components, you can specify an offset value and a scaling factor (scalar) for each of these parameters. The modified value will be calculated as: scalar times (original value + offset value).