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Wankel rotor Deforming mesh and motion UDF_Help please

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Old   August 2, 2011, 08:45
Default Wankel rotor Deforming mesh and motion UDF_Help please
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Dear all,

I am at the final year of my PhD and my last task is to model the volume variations is a Wankel engine chamber.

I am trying to specify a dynamic mesh motion for the first time but I'm lost with the eccentric mounting of the shaft.

I have equations for the rotor apex circumferential velocity so let's say I know the apex location for any time instance but the center of gravity thing confuses me.
Also, in the CG macro definition I need to define linear velocity which looks to me inappropriate as I don't have reciprocating motion so maybe another macro is appropriate?

It's been sometime since I dealt with kinematics & dynamics and I'm a bit rusty

Another thing ( assuming I figured out the motion definition), it's not an in-cylinder application so what should I use in Fluent? six dof or I don't have to click anything?

I apologize if my lack of experience is annoying.

Any help would be appreciated?

All the best,
Thanos
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Old   August 3, 2011, 08:04
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To make it a bit more specific;

I have read that the deforming volume mesh should not be bound i.e. should be divided in 3 distinct volume meshes by the rotor apex seals.

If this was not the case I guess I could somehow specify that the rotor apexes are in continuous contact with the housing and compiling a simple UDF for the rotation about the CG of the rotor could suffice.

Since the rotor apexes do not touch the housing then rotation around the CG is inapplicable (imo) as the eccentric motion needs to be specified.

Now, the apex velocity equation describes the motion in the housing but then the CG macro would be wrong, right?

Any ideas anybody?

All the best
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