Solid Body rotating
 

I am new to this forum, and I hope, that someone would help me with little problem. How can I specify rotational velocity using CEL on a hemisphere?

RotationAngle = omega * time

omega is your rotational velocity, and set your hemisphere angle to RotationAngle.

I appreciate your responde, but can you tell me, how can I set hemisphere angle to my expression?

You have not yet said what you are trying to do. Are you using an immersed solid, rotating frame of reference or moving mesh approach? They are all different.

I tried to use rotating frame of reference, it seems to be the simplest way, but I still don't really understand how can I set one.

You still have not explained what you are trying to do. Can you post an image?

http://img861.imageshack.us/i/93422970.jpg/

As simple as that. I need to set this hemisphere rotating around Z axis, and then set an airflow around it, to determine what's going to happen with the flow depending on velosity of rotation

In that case no need for any of that. Just put a tangential velocity on the hemisphere surface. You will need to define a CEL expression to evaluation the tangential velocity as a function of XYZ location but that should be easy.

This is then a simple analysis with no moving mesh, rotating frames of reference or anything tricky. Easy.

So I need to use wall boundary for hemisphere surface, and then give it tangential velocity?

Therefore, I understand, how to set a tangential velocity ac a function of XYZ location, but I dont understand what to do with time dependence.

What time dependence? Is the angular velocity changing with time?

well, if I'll write this expressions:
R=(x^2+y^2)^(1/2)
f0=asin(x/R)
X1=R*sin(f0+RotationAngle)
Y1=R*cos(f0+RotationAngle)
RotationAngle=Omega*Time
That will do the right thing?

and no, angular velocity is constant

I think you have missed the point. We are modelling in a Eularian frame so what the fluid sees at any point on the surface is just a constant tangential velocity. There is no time component.