# Why my 3D 1DOF overset mesh wont give any rotation?

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 August 24, 2022, 13:18 Why my 3D 1DOF overset mesh wont give any rotation? #1 New Member   aykay Join Date: Dec 2021 Posts: 5 Rep Power: 3 Hi, I have a fan enclosed in 3D overset mesh domain. I wish to calculate (1DOF free rotation) RPM (rotation/min) of the fan in response to an incoming flow with M = 2.16, angle of attack = 0. There are four deflected flat plates approximately 0.7 meters away from the fan. I want to study the effects of the flow disturbance caused by these flat plates on the RPM of the fan (which I want to calculate through 1DOF free-rotation). MOI of the fan is 0.001 kg/m2. The case fully converges at 0.4s with e-4 time-step. Though I slightly see some movement in fan geometry (about 1degree) but my overset mesh just wont rotate fully and record any roll angle/ roll moment. . according to reference papers, I should be getting 4 full rotation cycles by this flow-time. What I may be doing wrong?

 August 24, 2022, 19:09 #2 Senior Member   Alexander Join Date: Apr 2013 Posts: 2,344 Rep Power: 33 never did same simulation, but: why should mesh rotates? mesh doesn't know its a fan I feel like you should apply force somehow (for example through UDF) as it seems, that its not applied automatically. __________________ best regards ****************************** press LIKE if this message was helpful

August 24, 2022, 19:26
#3
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aykay
Join Date: Dec 2021
Posts: 5
Rep Power: 3
Quote:
 Originally Posted by AlexanderZ never did same simulation, but: why should mesh rotates? mesh doesn't know its a fan I feel like you should apply force somehow (for example through UDF) as it seems, that its not applied automatically.
Dear Alexander, thanks for writing to me.

The mesh should rotate because of the angled airflow coming from the deflected plates that I have placed in front of the fan.

Just like how water flow rotates the blades of a turbine

I wish to calculate RPM of the free-rotating fan. Instead of using a UDF, I have setup the same rotating domain using 1DOF dynamic mesh motion for the overset (fan) zone.

 Tags 1dof, fan, overset mesh, roll motion, rotation rate