Learning Forum

[tpsagaro]

Hi,

Fluent recommends using the sliding mesh technique to simulate, for example, the rotating region of a centrifugal pump:

https://forum.ansys.com/forums/topic/analysis-of-impeller-sliding-mesh-method/?order=all#comment-d7da4c9f-acb8-4e02-8707-a8ee006123c9

In that tutorial, however, there appears an unrealistic discontinuity of velocities through the rotating-static interface. The sliding mesh technique to describe the rotation of the volume assigns a turning velocity to the fluid that conflicts with that of the static zone at the other side of the interface. In other words, it looks like that the flow in the rotating domain behaves as a (rotating) rigid body. From the above, my first question is:

Does the sliding mesh technique applied to a rotating domain impose a turning velocity to fluid cells?  

In case yes, my second question is:

How can the sliding mesh technique properly calculate forces and torques over the blades of an impeller (e.g., turbine) if it artificially imposes a turning velocity to the fluid cells that are in contact with the blades?

I thought that the sliding mesh technique implied changes in the geometry (e.g., by moving the blades) but was invariant for the flow fields. 

Thanks,

 

 

[Rob]

A discontinuity is often caused by the mesh not being overly well matched for size, and/or poor convergence.  I think the theory is covered in the Fluent Theory Guide: please look through that.