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Calculated torque value not matching with fluent value

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Old   December 6, 2020, 07:53
Smile Calculated torque value not matching with fluent value
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Jahaan
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Hi everyone

I am a student, recently gained intrest in CFD and started working on small cases to learn and understand tool and physics.

I have been working on a simple case of "transient simulation, Flow over a rotating circle -2D". I am using pressure inlet and outlet as boundry conditions, with constant RPM. My challenge is i am not able to match calculated torque value and fluent torque value. Also I have observed that torque value is changing with time even tough with constant RPM

Need help to figure out my case. Thanks in advance
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Old   December 6, 2020, 19:42
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If you want help, you have to share some more details.

At minimum:
-which pressures and flow rate did you use?
-what is the torque value calculated by you?
-how did you calculate that?
-what is the torque value calculated by fluent?
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Old   December 10, 2020, 11:03
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Hi Pakk,

Thanks for your reply, my apologies for not giving complete information.

I have used simple model of (R)0.07m circle in a rectangular domain, Circle rotating with 1780.23 rad/sec. I have used KOmega solver with boundry condition (Pressure inlet and pressure outlet) in transient case and ran for 4 sec, ANSYS torque value is 19Nm.

I have theoretically calculated torque value by (Moment of inertia of circle (I) X Angular acceleration (Alpha)) and the derived value is 0.008Nm.

I am not able to understand where i am going wrong.

Thanks for asking me :-)
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flow over a cylinder, fluent, torque, transient

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