[Jonathan]

Dear All,

I wonder if someone can clear this up for me: I find the units in CFD-Post confusing, particularly wrt flow angles etc:

For instance:

1) You seem to be able to 'set' the units for the various flow angles (imported Fluent quantities as well as native / calculated CFD-Post quantities) in the Variables tab. This would lead me to assume that whatever unit you choose in the Variables tab (i.e. radians or degrees), is what is used throughout the remainder of the software.

2) However, if i define a custom variable, say alpha, using Velocity in Stn Frame Flow Angle (set in degrees) in the Variables tab, as

alpha = 90 - Velocity in Stn Frame Flow Angle

in the Expressions tab, i will still end up CFD-Post telling me my Expression alpha is defined in radians in the Details panel for that Expression.

Further, if i take say:

Velocity Angle

defined in Variables as radians, and i do something like:

aveangle = massFlowAve(Velocity Angle)@X3

in the Details tab for that expression, i will end up with it being defined as degrees ...

3) There is also a Set units pane in the Options / Preferences menu, but i'm not sure how this affects everything else.

4) Finally, do the trig functions in CFD-Post want the angles defined as radians or degrees ...


THen despite everything, it seems that contours etc are always display as DEGREES, so i actually have no idea how CFD-Post imports / works with variables, especially flow angles ... so despite whatever units your variables are set / defined as, it will display them as Degrees.

This is all very confusing, and since i am working with secondary flows in turbines, getting the flow angles in the various reference frames correct is very important.

Any help from CFX gurus would be much appreciated - many thanks
Cheers
Jonathan

PS I am importing my solutions from Fluent data files, if that makes any difference. Jon