July 25, 2019 at 11:40 amMrFCASubscriber
I am simulating the performance of a centrifugal pump.
First, I simulated the centrifugal pump without roughness to have a approximate results, but when I have simulated it with roughness, the convergence becomes disastrous.
Any idea why this happens?
For the solid boundaries, the no-slip condition with relative roughness is 100 micron. I know that the setup asks for roughness in "Sand Grain Roughness". Fo this reason I put 0.0005863 m.
I attach the photos of convergence without roughness ad rougnhness.
July 26, 2019 at 1:41 pmRobAnsys Employee
Check the time step and/or substepping (I don't use CFX). It's possible the roughness has triggered a change in the flow field (separation point or similar) so a smaller step may be needed?
July 27, 2019 at 11:07 amRaef.KobeissiSubscriberAre you using second order for your equations?
July 29, 2019 at 7:45 am
August 1, 2019 at 12:26 pmMrFCASubscriber
Any more idea?
August 1, 2019 at 1:24 pmRobAnsys Employee
Assuming it's transient, can you see any changes in the flow field?
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