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-   -   Multiphase, how to change my simulaiton to "transient?" (http://www.cfd-online.com/Forums/cfx/79324-multiphase-how-change-my-simulaiton-transient.html)

zmaxcomputer August 19, 2010 18:20

Multiphase, how to change my simulaiton to "transient?"
 
I have a simulation with 3 particles, and i would like to figure out a way to see if i can get some to "stick" to the wall of my vessel. I changed my wall interaction from "Equation Dependent" to "Wall Film". However, i can not see to fix this error. I have changed every valuable imaginable. Any ideas? I can upload screen shots if that would help anyone...i just dont know what i would upload.

Thanks a lot everyone! Ive been trying to fix this for a while......

"Simulations involving the particle wall film option are only allowed for transient simulations. Please change your setup and rerun the case."

ghorrocks August 19, 2010 18:28

Only use the wall film model if you actually want to model a film on the wall.

If you want your particles to stick to the wall simply use a restitution coefficient of 0 on the wall you want it to stick to.

zmaxcomputer August 20, 2010 05:02

Hi!

I selected "default domain default" and switched from wall film to "equation dependent". Where it says velocity i selected perpendicular coeff to 0, as well as parallel coeff to 0. Minimum impact angle, erosion model, mass flow absorption and particle behavior were not selected.

When i run it (and there are no errors!) i am able to get to CFD-post but when i run the animation the little balls still go all the way through, they still dont stick.

Am i doing something wrong?

Thanks again!

ghorrocks August 22, 2010 18:28

Yes, you are doing something wrong. Turn the wall film model off! Wall films can absorb and emit particles and so appear as if the particles are bouncing off.

Also note you set the restitution coefficients per wall area so if you have multiple wall areas you will need to set it for each wall.

zmaxcomputer August 23, 2010 00:26

I did that, and after a bunch of simulations i noticed a few of the particles stop, but only after they hit the wall, then they roll for a while, then stop....then they disappear. Is there a way to fiddle with the settings so that as soon as the balls hit the wall they stop immediately? And stay there so i can count them?


Thank you very much for your time!

ghorrocks August 23, 2010 07:33

If you have the restitution coef set to 0 then they are not hitting and sliding. They will be a small distance off and caught in the boundary layer.


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