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-   -   help on Immersed Solid approach (http://www.cfd-online.com/Forums/ansys/93780-help-immersed-solid-approach.html)

anori October 26, 2011 10:24

help on Immersed Solid approach
 
3 Attachment(s)
Hello everyone,

I am new to Ansys and I am doing a research project with my professor to study the Immersed Solid approach. I have been searching extensively for tutorials, guides, suggestions, etc. but I find it not to be that easy.

I am modeling two cylindrical discs (no teeth; pure cylinder) which are rotating counter-directional of each other in a fluid domain. A rotation is applied to the disks which are immersed solids. There is a gap of 5mm space between. My objective is to see the pressure and velocity change of the fluid.

The problem I am coming up with is a unreal pressure difference betweeen max and min.

I suspect is it due to the meshing at the 5mm wide gap. Since IS technique is not quite reliable for boundary layer analysis (correct me if I am wrong) I suspect the 5mm gap zill overlap the boundaries of both disks. The only solution I see woul be to make the meshing at the gap very very fine.

Thanks

Far October 26, 2011 11:00

Looks like a converging diverging nozzle type effect (forced type flow)

anori October 27, 2011 09:42

Quote:

Originally Posted by Far (Post 329559)
Looks like a converging diverging nozzle type effect (forced type flow)


Is this a problem for IS approach?

Also, woul someone kindly explain momentum scale factor for me. From what I read I suspect it might a variable I should adjust but I don't completely understand what it does exactly.

Thanks

Far October 27, 2011 10:44

Well I ain't expert of IM method, so can not say further.

Far October 27, 2011 10:50

http://www.edr.no/blogg/ansys_blogge...mmersed_solids

This might be helpful, if you didn't come across this already

anori October 28, 2011 08:40

Quote:

Originally Posted by Far (Post 329746)
http://www.edr.no/blogg/ansys_blogge...mmersed_solids

This might be helpful, if you didn't come across this already

EDIT, nevermind.

Thanks

belgacem May 25, 2012 06:02

Hi Friends
I am also studying immersed boundary method and and try to simulate a block falling in the water. I am using "immersed solid" then rigid body 6DOF and I let it fall freely but it can't stoped in the bottom where the velocity must be zero. I give a density to the block and i let it fall freely under gravity. Noted that the rigid body is defined as an immersed solid. i have specified a stationary coordinate frame that has its origin at the center of mass of the physical rigid body. Another fixed coordinate frame was specified related to the water at rest.
What can I do to stopped the rigid body in the bottom where the potentiel energy must be zero?

thank you!


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