### Error in data alteration using "dd(Theta)({c_r})"

Posted:

**Mon Nov 09, 2015 4:29 am**Hi,

i want to calculate the vorticity in polar coordinates using the following equation:

{omega_ax_polar}=(ddR({R}*{c_u})-dd(Theta)({c_r}))/R

But tecplot gives the error: Unrecognized command for "ddTheta". I tried "ddTheta", "dd(Theta)", "dd({Theta})", "dd{Theta}" and I even changed "Theta" to "T" and used "ddT", but nothing worked. I can´t explain why it isn´t working. The data set i got is a slice behind the first guide vane from a CFD-Simulation of a turbine. It´s clear, that a derivation in the direction of flow is not possible, but a derivation in Theta-direction should be, shouldn't it?

I hope someone can help me. If you need further information please tell me.

Best regards,

Kristina

i want to calculate the vorticity in polar coordinates using the following equation:

{omega_ax_polar}=(ddR({R}*{c_u})-dd(Theta)({c_r}))/R

But tecplot gives the error: Unrecognized command for "ddTheta". I tried "ddTheta", "dd(Theta)", "dd({Theta})", "dd{Theta}" and I even changed "Theta" to "T" and used "ddT", but nothing worked. I can´t explain why it isn´t working. The data set i got is a slice behind the first guide vane from a CFD-Simulation of a turbine. It´s clear, that a derivation in the direction of flow is not possible, but a derivation in Theta-direction should be, shouldn't it?

I hope someone can help me. If you need further information please tell me.

Best regards,

Kristina