Angular Motion

Angular motion is the rotation of an object about a centerline.

Examples of applications that use Angular Motion include:

• Positive displacement pumps
• Gear pumps
• Trichodal pumps
• Check valves
• Reed valves

Unlike the Rotating Region material device, objects with an angular motion can have paths that interfere--such as gear teeth in a gear pump or multiple mixing blades in an egg-beater.

Use the following guidelines to determine which method, angular motion or rotating region, you should use for your devices:

The lobed cam rotates about its center. Its lobes mesh with the static lobes of the surrounding piece. Flow is induced through a positive displacement mechanism by changing the volume of the flow region. Use Angular Motion to define this motion.

Turbomachinery devices (centrifugal, mixed-flow, and axial pumps and turbines) should be analyzed using Rotating Regions:

The impeller in this centrifugal compressor rotates, but does not touch any other solid object. It induces flow by transferring energy to the fluid (through a momentum transfer, in the classic turbomachinery sense.) Use a Rotating Region to define this motion.

Assign Angular Motion to devices that move fluid (liquid or gas) using a volume displacement or that simply move through fluid. Conversely, surround a rotating device with a rotating region that moves fluid through an energy transfer. Such devices rely on the Coriolis effect and centripetal acceleration.

Rotating regions will produce a more accurate answer, and typically require less computational resources. Moving solids (specified angular motion) are more versatile, and can solve a wider variety of applications.

The following table lists several devices, and how the rotational motion should be specified: