Calculated torque value not matching with fluent value

Jahaan · December 6, 2020, 08:53

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

pakk · December 6, 2020, 20:42

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?

Jahaan · December 10, 2020, 12:03

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 :-)

December 6, 2020, 08:53	Calculated torque value not matching with fluent value	#1
Jahaan New Member Jahaan Join Date: Dec 2020 Posts: 4 Rep Power: 6	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

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Torque calculation with fluent	s wang	FLUENT	11	February 9, 2017 10:45
Pressure calculated by Fluent	souria	FLUENT	4	November 10, 2015 04:30
Torque in Fluent	visitor	FLUENT	0	November 7, 2015 04:44
The fluent stopped and errors with "Emergency: received SIGHUP signal"	yuyuxuan	FLUENT	0	December 3, 2013 23:56
Possible Bug in pimpleFoam (or createPatch) (or fluent3DMeshToFoam)	cfdonline2mohsen	OpenFOAM	3	October 21, 2013 10:28

December 6, 2020, 20:42		#2
pakk Senior Member Join Date: Nov 2013 Posts: 1,965 Rep Power: 27	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?

December 10, 2020, 12:03		#3
Jahaan New Member Jahaan Join Date: Dec 2020 Posts: 4 Rep Power: 6	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 :-)