# Rotating Arm Simulation

Discussion in 'Stability' started by dtoshni, Jun 25, 2009.

1. Joined: May 2008
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### dtoshniJunior Member

Hi everyone!

I am trying to simulate a small fully-submerged ellipsoid rotating about a point. For the rotating arm simulation. I have defined a domain around the ellipsoid as fluid. Now I proceeded to solve for the forces, moments etc.

Approach 1:
At the Inlet, defined the fluid velocity as angular, of the appropriate magnitude, and with the apt rotation axis. All this in absolute terms.

Approach 2:
At the Inlet, defined the fluid velocity as angular, of the appropriate magnitude, and with the apt rotation axis. Also, defined the ellipsoid as rotating about the rotation axis. All this in absolute terms.

Could you please help me out over here and tell me which approach is correct? Would all the extra terms due to the circular motion (centrifugal forces) be included in approach 2 and not 1? Please can anyone help me out with this?

By approach 2, wouldnt the viscous force increase? Because the velocity of the fluid relative to the ellipsoid will increase and become the (velocity of the ellipsoid + Tangential velocity of the fluid) right? So does that make the first approach correct? Does Approach 1 take into account the centrifugal forces too?

Is there something else I need to do along with this because the final solution for moments reported by FLUENT is very small.

Also, in a rotating arm test, are the iso-velocity profiles concentric, or the isobaric profiles concentric? Can any one of you please please help me out with this..I've been stuck in this rut for a long time now..

2. Joined: Jul 2009
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Location: lindapret88

### lindapret88New Member

I am not so knowledgeable about this matter. So i have to learn it. Thanks for the post.

taux pret auto

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