[NumericCFD]

I have modelled a Francis turbine runner on Ansys CFX. The results file provides the ability to plot a pressure contour map over the blade (image 'Pressure').

I am trying to plot the Thoma number which will require using the pressure value at each node (or point) along the blade for a calculation (image 'Desired Contour' shows the desired contour I'm trying to produce, sourced from a provided report.)

The expression I intended on using was (Pi-Pv)/(rho*g)*)(1/Hn), where Pi is the pressure value at each point. When I attempt to write this as an expression, I can not obtain the correct function to compute individual pressure values as indicated by the images, and hence am unsure on how to proceed


Thankyou for your help, I appreciate it

[ghorrocks]

You appear to be attempting to add it as a CEL expression. This is not the correct approach. You need to add it as a new user variable (not a CEL expression) and define the variable to have the expression you want for the value. The expression should probably be something like (p-1228[Pa])/(998*9.81)*(1/86.6)

[NumericCFD]

Originally Posted by ghorrocks

You appear to be attempting to add it as a CEL expression. This is not the correct approach. You need to add it as a new user variable (not a CEL expression) and define the variable to have the expression you want for the value. The expression should probably be something like (p-1228[Pa])/(998*9.81)*(1/86.6)

Thankyou that is big help!

Are you able to direct me to the correct user guide as to how to identify different parameters for use in expression/solver computations. I was unable to find the documentation that the 'p' in "(p-1228[Pa])/(998*9.81)" was automatically registered for pressure in any ansys documentation.

As always thankyou for your swift replies

[ghorrocks]

The CFX Reference guide has several chapters on CEL, including functions, available variables (such as "p") and how CEL works.