# Question about immersed solid method in CFX

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 January 2, 2011, 20:28 Question about immersed solid method in CFX #1 New Member   Shui Pei Join Date: Mar 2009 Posts: 20 Rep Power: 8 Hello: I am studying immersed boundary method and and try to simulate a ball falling in the water. I am using "immersed solid", is that OK? I find I can give a specified velosity to the ball, but I cannot give a density to the ball and let it fall freely. What can I do? thank you!

 January 4, 2011, 16:41 #2 Senior Member   Edmund Singer P.E. Join Date: Aug 2010 Location: Minneapolis, MN Posts: 494 Rep Power: 11 What are you using the density for in the solid? Having it float in the water? You will need to write that into a CEL expression that controls the motion (velocity) of the ball, or look into using Rigid Body (6DOF), if that is the case.

January 4, 2011, 19:52
#3
New Member

Shui Pei
Join Date: Mar 2009
Posts: 20
Rep Power: 8
Quote:
 Originally Posted by singer1812 What are you using the density for in the solid? Having it float in the water? You will need to write that into a CEL expression that controls the motion (velocity) of the ball, or look into using Rigid Body (6DOF), if that is the case.
I want to simulate a metal ball fall by gravity in the water.
Where can I selcet the 6DOF solver for a rigid body?
I find little setting opions for a immersed solid.

 January 5, 2011, 14:34 #4 Senior Member   Edmund Singer P.E. Join Date: Aug 2010 Location: Minneapolis, MN Posts: 494 Rep Power: 11 What version of cfx are you using? Rigid Body Solver is beta in V12 and full feature in V13. Beware in V12. You must use the Global coordinate frame as the rigid body coord (there is a bug when it uses a different coordinate system).

January 7, 2011, 11:04
#5
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Shui Pei
Join Date: Mar 2009
Posts: 20
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Quote:
 Originally Posted by singer1812 What version of cfx are you using? Rigid Body Solver is beta in V12 and full feature in V13. Beware in V12. You must use the Global coordinate frame as the rigid body coord (there is a bug when it uses a different coordinate system).
Thank you for your reply, I am using CFX12.1. Where can I find the relate plane to set the proferty like density for the immersed solid? Sorry for this stupid question, but I am still finding the plan......

 May 22, 2012, 08:24 #6 New Member   belgacem Join Date: Jan 2012 Posts: 22 Rep Power: 5 Hello: 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!

 May 24, 2012, 13:05 #7 New Member   belgacem Join Date: Jan 2012 Posts: 22 Rep Power: 5 Hello: 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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