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nikwin December 15, 2011 05:45

relative velocity for a radial turbine wheel
Hi all,

I have a set of transient data for a radial turbine including the event file (.evn) and would like to compute the relative velocities in the wheel. The wheel rotation is simulated with the sliding mesh technique. Could anyone please give me a hint of how to or point me to a relevant tutorial.


JBeilke December 15, 2011 08:20

Use the "reframe" command.

nikwin December 15, 2011 08:24

Thanks for your quick reply!

I've tried the following, reframe,2,local,(OMEGA), used the second coordinate system with the following command, csys,2 and then tried to extract the data again. However, it subtracts the data from the entire field and not just from the wheel. Do you know how I can specify a part of the field to get relative velocities at the wheel only?

All the Best

JBeilke December 15, 2011 09:48

There are 3 possibilities for using the command.
  • refr stat
  • refr compu
  • refr loca icsys omega
Just try what gives the best results.

I don't see an easy solution for the other problem right now.

RobertB December 15, 2011 12:54

I would think that you should be able to get there from here with OPERATE and CHANGE

If you use PSYS to set the basic system for post processing

Then you can


to get the vectors in the axis of the rotor

Oper getc x axis_syst 5

Oper smult omega 5 5

Cset news all non rotating cells

change cset 0 0 0.0 0.0 5

oper subt 2 5 2

Oper unrotate

Not sure if this does exactly what you want but some combination of the above commands or similar should get you there from here

nikwin December 22, 2011 11:33

Thank you! The command oper,refr,local,(coord syst),(omega) did the trick!

All the Best

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