value of Wmax
 

I've been looking at Tutorial 9 on CFX, flow through a butterfly valve. I ran the computation first with Wmax=5m/s and then =20m/s and calculated the loss coefficient which came out to be equal for both values of Wmax. In the literature I've been given, it says not to increase Wmax by a factor of more than 5, why does the increase to Wmax have to be limited?

Thanks

Perhaps you can't obtain steady-state convergence at higher velocities?

Tristan

This might sound ridiculous, but what does steady-state convergence mean?

Thanks

The code is able to find a converged solution to the steady state equations i.e. there's no time variation in the solution. As you increase the flow velocities, the code may not be able to find a steady state solution and you have to perform an unsteady analysis which takes a lot longer to run and would therefore not be desirable for a tutorial.