Need help on FSI analysis and Re-meshing Approach

khinthida2005 · September 3, 2009, 04:47

Hello eveybody!
I am new to CFX and ANSYS.
I have to study about FSI analysis for helicopter hydraulic actuator system
which consists of two piston cylinder parts. Here're the figures for structural part and fluid part that I have to analyse .

this is the helicopter actuator system

this is the structural part

this is the fluid part

this is FSI coupled analysis I have to apply for my case.

What I want to know is
(1)Do you have any related examples for FSI analysis like this?? If so, could you help me please?? Here's is my mail
khinthida2005@gmail.com
Click Here to Email Me
And the second one is

(2)I have no idea about re-meshing approach. So warmly welcome for any comments, help and also your idea. How can I apply this re-meshing approach for my analysis?? Do you have any examples or any documents related this ?

May all of you happy in everyday of your life!! Thank you all!

ghorrocks · September 3, 2009, 06:14

Can I ask why are you doing this as an FSI problem? It looks like a fairly standard hydraulic component and generally the structural component can be modelled statically, and the fluid bit can be modelled with specified motion. This is much easier to do.

khinthida2005 · September 3, 2009, 10:01

Firstly, I would like to say special thanks for your kindness,Ghorrocks.
In my opinion,there is some interaction between hydraulic oil and two-piston
cylinder parts . So I have to analyse this as a FSI problem .
Thank you!
Anyway, nice to meet you!

ghorrocks · September 3, 2009, 18:51

Of course there will be interaction between the oil and the piston - that is how hydraulics works. But is the interaction such that you need FSI? If in your model the fluid merely moves the piston then this is better done as a separate structural and fluids simulation as I explained before. I would only consider FSI if the interaction was important - maybe the fluid pressure causes the cylinder to expand which causes the fluid to significantly change.

Can you explain why you think FSI is needed?

khinthida2005 · September 3, 2009, 21:02

Thanks again ghorrocks! Because there is another pressure forces which interact inside the fluid model. Sorry for my bad explanation! As you seen in the fluid part, there is
two pressure inlets and two pressure outlets. That's why I think FSI is needed for this case!

The inlet and outlet conditions are as shown:

Inlet = 20.7 MPa for each inlet
outlet = 0.517 MPa for each outlet

May you be happy in everyday of your life! Thank you so much !

ghorrocks · September 4, 2009, 07:56

I don't think you understand what I am saying. Have a look at the ball valve tutorial example. This assumes the ball is a rigid body, but is moved by the fluid. This does not require FSI but the fluid flow/pressure moves the object. This is the sort of model which I would imagine would normally be used for hydraulics modelling.

September 3, 2009, 04:47	Need help on FSI analysis and Re-meshing Approach	#1
khinthida2005 New Member khinthida Join Date: Apr 2009 Posts: 3 Rep Power: 16	Hello eveybody! I am new to CFX and ANSYS. I have to study about FSI analysis for helicopter hydraulic actuator system which consists of two piston cylinder parts. Here're the figures for structural part and fluid part that I have to analyse . this is the helicopter actuator system this is the structural part this is the fluid part this is FSI coupled analysis I have to apply for my case. What I want to know is (1)Do you have any related examples for FSI analysis like this?? If so, could you help me please?? Here's is my mail khinthida2005@gmail.com Click Here to Email Me And the second one is (2)I have no idea about re-meshing approach. So warmly welcome for any comments, help and also your idea. How can I apply this re-meshing approach for my analysis?? Do you have any examples or any documents related this ? May all of you happy in everyday of your life!! Thank you all! Last edited by khinthida2005; September 3, 2009 at 09:55.

September 3, 2009, 10:01		#3
khinthida2005 New Member khinthida Join Date: Apr 2009 Posts: 3 Rep Power: 16	Firstly, I would like to say special thanks for your kindness,Ghorrocks. In my opinion,there is some interaction between hydraulic oil and two-piston cylinder parts . So I have to analyse this as a FSI problem . Thank you! Anyway, nice to meet you! Last edited by khinthida2005; September 3, 2009 at 10:22.

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September 3, 2009, 06:14		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,697 Rep Power: 143	Can I ask why are you doing this as an FSI problem? It looks like a fairly standard hydraulic component and generally the structural component can be modelled statically, and the fluid bit can be modelled with specified motion. This is much easier to do.

September 3, 2009, 18:51		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,697 Rep Power: 143	Of course there will be interaction between the oil and the piston - that is how hydraulics works. But is the interaction such that you need FSI? If in your model the fluid merely moves the piston then this is better done as a separate structural and fluids simulation as I explained before. I would only consider FSI if the interaction was important - maybe the fluid pressure causes the cylinder to expand which causes the fluid to significantly change. Can you explain why you think FSI is needed?

September 3, 2009, 21:02		#5
khinthida2005 New Member khinthida Join Date: Apr 2009 Posts: 3 Rep Power: 16	Thanks again ghorrocks! Because there is another pressure forces which interact inside the fluid model. Sorry for my bad explanation! As you seen in the fluid part, there is two pressure inlets and two pressure outlets. That's why I think FSI is needed for this case! The inlet and outlet conditions are as shown: Inlet = 20.7 MPa for each inlet outlet = 0.517 MPa for each outlet May you be happy in everyday of your life! Thank you so much !

September 4, 2009, 07:56		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,697 Rep Power: 143	I don't think you understand what I am saying. Have a look at the ball valve tutorial example. This assumes the ball is a rigid body, but is moved by the fluid. This does not require FSI but the fluid flow/pressure moves the object. This is the sort of model which I would imagine would normally be used for hydraulics modelling.