[csaban]

Hello,

I am relatively new to CFD and am trying to use a cel expression for two inputs. Fiestly for changing rotational velocity of a domain, I wish to slow rotation from 222rad/s to 44rad/s in 4 seconds and input this as anexpression for rotational velocity.

And secondly to use an expression for inlet velocity to reduce from 50ms-1 to 10ms-1 in 4 seconds also.

Thanks

[evcelica]

This is really basic stuff. You should have a look in the documentation or tutorials to learn how to do this kind of stuff, or you will be asking simple questions forever. There are several ways you can do it: User functions, CEL, + more

CEL is not complicated, and you can even make an expression and plot it in CFX Pre to see if you have it correct.
These can both be plotted using the equation of a line with a slope
y = mx+b
V(t) = m*t + Vo
m is your slope, value change over time. [m/s^2]
Vo is your value at t=0s

Or just make a user function, and put in your data points.

[csaban]

Apologies,
I forgot to upload the picture, I have tried this but i'm not sure why it's wrong ?

[Opaque]

If you check your plot legend for the Y-axis, you will notice the units are [s^-1].

Where is the problem?

If you now look to your variables carefully, you have not spaced the units properly ms^-1 is millisecond while [m s^-1] is meter per second.

Same for the acceleration. Since you made the same mistake twice, the equation term are consistent, but not what you expected..

Good luck