butterfly valve
 

Hello People!
I take this oportunity to ask you all for some help...
I trying to study a transient flow through a butterfly valve during its openning process
so that, I would like to rotate a butterfly valve 45º (from close stage to open stage)
Can you explain me how to do that?

do I have to write a UDF to generate the move?
because I don´t have any idea (even after reading the udf manual)

isn´t there any standard procedure to get it done?

thanks in advance