help on Immersed Solid approach

anori · October 26, 2011, 10:24

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

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

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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October 26, 2011, 11:00		#2
Far Super Moderator Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,553 Blog Entries: 6 Rep Power: 54	Looks like a converging diverging nozzle type effect (forced type flow)

October 27, 2011, 10:44		#4
Far Super Moderator Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,553 Blog Entries: 6 Rep Power: 54	Well I ain't expert of IM method, so can not say further.

October 27, 2011, 10:50		#5
Far Super Moderator Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,553 Blog Entries: 6 Rep Power: 54	http://www.edr.no/blogg/ansys_blogge...mmersed_solids This might be helpful, if you didn't come across this already

May 25, 2012, 06:02		#7
belgacem New Member belgacem Join Date: Jan 2012 Posts: 22 Rep Power: 14	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!