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eric September 16, 2003 07:59

rotating wall
Hi all,

I have a flow through a rotating drum, similiar to a rotating cement/lime kiln. The drum is rotating at 0.21 rad/s and the inlet velocity is 18m/s.

I want to know what effect the rotation has on the flow, and if it is necessary to account for the rotation?

Can i use steady state model and simply set the wall rotating in the boundary conditions at 0.21rad/s?????

Can anyone give me advice on what to do?



david September 16, 2003 08:02

Re: rotating wall
No you can't use steady state


prasat September 16, 2003 08:11

Re: rotating wall
Hi I think as first approximation just use steady stae and run for large time and then see whether the problems in really steady state or not. If you are not convenced then probabaly use unsteady case and do the simulation

eric September 16, 2003 09:13

Re: rotating wall
Thanks guys,

What about using multiple reference frames is that possible? will it produce the same effect?

I think the fact that the drum is rotating so slowly that maybe the steady state approximation, using MRF, may be possible!

What are you views???

Thanks, Eric

ap September 16, 2003 11:48

Re: rotating wall
I agree, I don't think you can properly represent your case using a steady calculation.

Hi :)


eric September 17, 2003 05:19

Re: rotating wall
Thank for your advice,

I will try an unsteady simulation.

My model consists of a windbox, which stationary, then the rotating drum and then into a stationary exit. The flow enters at the windbox, flows through the rotating drum and exits.

Can i follow the same method as that in the "Using VOF model" tutorial for unsteady flow, i.e. solver = unsteady and wall boundary condition = moving wall/rotation????

I ask because in that tutorial above, the whole system is rotating where as my domain has both stationary and rotating components.

Thanks for your help


ap September 17, 2003 08:10

Re: rotating wall
The procedure should be the same of the tutorial case, but when you generate the grid in GAMBIT, you have to assign separate wall boundary conditions to the rotating wall and to the stationary one.

Hi :)


eric September 17, 2003 08:54

Re: rotating wall
Yes seperate walls. Just to confirm - I should have a wall to represent the rotating walls and another wall to represent the stationary walls?

How do i know that the walls have actually rotated, will the post-processing show the rotation of the wall or show the wall at different angle after x time steps???

Thanks ap


ap September 20, 2003 17:49

Re: rotating wall
I think you should see the influence of rotation on the flow. I don't know if there is a way to see wall rotation in other ways.

Hi :)


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