When you solve a problem in Ansys Polyflow, you are typically modeling the flow in an inertial reference frame (that is, in a nonaccelerating coordinate system). However, Ansys Polyflow also has the ability to model flows in an accelerating reference frame. In this situation, the acceleration of the coordinate system is included in the equations of motion describing the flow.

A common example of an accelerating reference frame is flow in rotating equipment. Many such flows can be modeled in a coordinate system that is moving with the rotating equipment and thus experiences a constant acceleration in the radial direction. This class of rotating flows can be treated using a rigid rotation task in Ansys Polyflow.

For a rigid rotation task, Ansys Polyflow uses the relative velocity as the dependent variable, instead of the absolute velocity.

The relative velocity () is related to the absolute velocity () by the following equation:

(8–18)

where is the angular velocity of the rotating frame and is the position vector in the rotating frame.

To set up a rigid rotation task, choose Rigid rotation (in addition to any other appropriate options) as the type of task.

  Create a new task

When prompted, enter the value of the angular velocity .