# Angular velocity in fluent UDF

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 October 31, 2019, 04:16 Angular velocity in fluent UDF #1 New Member   gh Join Date: Oct 2019 Posts: 2 Rep Power: 0 Hello everyone,I'm using fluent UDF to define angular velocity for dynamic grid simulation, and the angular velocity was set 5ras/s,but the result of fluent calculation is different from what I defined. for example，the angular velocity was 5ras/s,the time to calculate one circle should be 2*pi/5=1.25s.But I calculated for a long time (such as 20s) and didn't reach a circle(2*pi). the code is below: DEFINE_CG_MOTION(side2,dt,vel,omega,time,dtime) { real flow_time = CURRENT_TIME; if(flow_time >=0) omega[2]=-5; } does anyone can help me? Thank you in advance

 October 31, 2019, 23:17 #2 Senior Member   Alexander Join Date: Apr 2013 Posts: 1,203 Rep Power: 20 what about Code: ```DEFINE_CG_MOTION(side2,dt,vel,omega,time,dtime) { omega[2]=-5; }``` how it works? __________________ best regards ****************************** press LIKE if this message helped you How to ask questions: https://www.cfd-online.com/Forums/si...tml#post612025

November 1, 2019, 01:17
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gh
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Quote:
 Originally Posted by AlexanderZ what about Code: ```DEFINE_CG_MOTION(side2,dt,vel,omega,time,dtime) { omega[2]=-5; }``` how it works?
hello AlexanderZ
the omega[2] represents rotation around the Z axis, with a size of 5 radians / s.

thank you .

 November 1, 2019, 02:53 #4 Senior Member   Alexander Join Date: Apr 2013 Posts: 1,203 Rep Power: 20 check if it works or not __________________ best regards ****************************** press LIKE if this message helped you How to ask questions: https://www.cfd-online.com/Forums/si...tml#post612025

 Tags angular velocity udf 2*pi