How to get the rotate speed in 6DOF simulation?
 

Hi everybody

I am using 6DOF to simulation the transient working of a turbin, 6DOF UDF and other settings now seem to work, but I have the problem of getting the varying rotate speed.

I have toggled the checkbox in 6DOF for "Write rotation history", and it writes a file about "time THETA_Z".

At first I thought I can calculate the speed (rpm) using 'THETA_Z' dividing 'time', However, the calclation results seem to be incorrect because the result is not a Continuous curve, but hops up and down between initial speed and a value that is slightly smaller than it

So I was wondering, is there any method that I can record or calculate the rotate speed of the domain?

Thanks very much!