Swirl Inlet Boundary Condition
The swirl inlet boundary condition is available on the overflow menu of the Boundary Conditions group when a fluid simulation study is the active study. The swirl inlet specifies the inlet velocity as the sum of two separate components, a component normal to the boundary (axial velocity) and a component with a radial velocity.
To Define a Swirl Inlet Boundary Condition
1. Click > 
Swirl Inlet. The Swirl Inlet dialog box opens.
Swirl Inlet. The Swirl Inlet dialog box opens.2. Specify a name for the boundary condition, or use the default name. Click the color swatch adjacent to Name to change the color of the icon, the distribution, or the text displayed for the boundary condition.
3. Select the surface at which to define the swirl inlet boundary condition.
4. The default coordinate system of the model is the reference coordinate system and is displayed in the Coordinate system collector. In the case of an assembly, the coordinate system of the top level assembly is the default coordinate system. If the model does not have a default coordinate system then the 
button is not available and the Coordinate system collector is empty. You can select any coordinate system, or create a UCS (user coordinate system).and designate it as the default coordinate system.
button is not available and the Coordinate system collector is empty. You can select any coordinate system, or create a UCS (user coordinate system).and designate it as the default coordinate system.You can also select an alternative reference coordinate system from the Model Tree or Graphics Window.
Click to return to using the default coordinate system of the model.
to return to using the default coordinate system of the model.5. Select one of the following options to define the magnitude and direction of angular velocity:
◦ Magnitude and direction—Specify the value of the unit vectors for direction by typing a value of 0, 1, or -1 in the X, Y, or Z field.
Alternatively click 
and select a linear edge or planar surface in the model to specify the direction of angular velocity. The value of the unit vector is displayed in the X, Y, or Z field.
and select a linear edge or planar surface in the model to specify the direction of angular velocity. The value of the unit vector is displayed in the X, Y, or Z field.Specify the magnitude of angular velocity in the Magnitude box.
◦ Directional components—Specify the components of angular velocity for each coordinate direction X, Y, or Z. The resultant direction and magnitude of velocity is determined from the values you specify for each coordinate. If you enter a positive value the velocity is applied in the same direction as the vector. If you use a negative value, the direction of velocity opposes the vector.
6. Select units of angular velocity from the list or accept the default units.
7. Specify a value of Axial speed and select units of velocity from the adjacent list.
8. Click OK to create and save the boundary condition.