[urosgrivc]

Hello,

Does anybody have an explanation on why the resulted Ventilation power loss
would be different in the CFX post if I add the units [radian s^-1] to the expression versus if I leave them empty.
The simulation is about a brake disc ventilation loss [W].
There is a large air domain around a brake disc and there is a cyclic symmetry included so there is 1/9th of the model or 40°.

the figure describing the problem:

cfxpostpowerevaluation.png

This is a screenshot from 2020R2.
What I would expect would be: [radian s^-1] * [N m]= [W]
[N m] is also equal to [J] so maybe there is a glitch somewhere or something that I can not figure out


I am almost sure that this was not the case in cfx18 and older
Thank You

[ghorrocks]

Please post images directly on the forum in future. Here is how: https://www.cfd-online.com/Wiki/Ansy...n_the_forum.3F

I do not know what is going on here. Not only does the calculation change numeric value, but the units also go wrong. Very weird.

[evcelica]

Those units and the numerical result are correct. I believe the problem is with radian and degree both being unitless.
So the second result is being shown as -12244.8 W*degree, which would equal -213.712 W*radian. Note kg*m^2/s^3 is equal to Watt.
Just leave radian out of the 100 if that is the correct way to specify power and you do not want it to include degree or radian in the results.

[Opaque]

Not certain if the behavior has changed between versions, but I would definitely look into the preferred units settings to display results.

If you have it set to use [degree], you will always see them in the displayed results and scaled accordingly.

I thought the default angle unit for SI was [radian]; otherwise, you can modify them to use the Custom option.