simulating fluid-moored struture

mary mor · September 19, 2013, 13:30

I'm going to model a floating body(breakwater) containing air chambers which can be compressed. The floating body has mooring lines.

My focus is to understand the wave diffraction of the floating body. The first question that comes to my mind is that can I generate wave in cfx?

I know that it's possible to simulate the body with mooring lines in ANSYS AQWA but as far as I know, no way to simulate the air chamber. Is there any way to combine both these modules?

I apprecite any help

ghorrocks · September 19, 2013, 18:01

CFX can do the model you are talking about but whether it is the most appropriate way of doing it is another question.

I would ask ANSYS support about AQUA and the possibilities of combining aqua with CFX/Fluent.

jdrch · September 19, 2013, 19:45

AFAIK from what I've read CD-Adapco's Star-CCM+ is the leader in free surface studies. Just my 2 cents. All the best!

ghorrocks · September 19, 2013, 21:12

Let me guess - that was from a Star-CD sales guy?

mary mor · September 20, 2013, 03:29

tanx horrock

you said it's possible to do it in cfx, but I couldn't find any tutorial or option that allows modeling mooring lines in cfx.

ghorrocks · September 20, 2013, 06:14

If you want to do simple models, like simple constraints where a rigid body is constrained to have X<some number, then this can be done in CFX.

If you want more complex models with the lines modelled with weight, stretch or other more complex features I would consider linking to ANSYS or AQUA (or doing it entirely in aqua).

mary mor · September 20, 2013, 07:23

The problem with AQWA is that as far as I know I can't model the air chamber. The air can exit from a slot opening above the chamber. This causes damping for structure displacement. consequently, it affects the wave height reflected from the body.

Best regards

ghorrocks · September 20, 2013, 07:46

I know very little about aqua and it capabilities, but I suspect you will have much more success with this model if you use aqua and develop a air chamber model for it; rather than use a multiphase model in CFX and use FSI to get the mooring lines. The CFX model is going to very complex and will require a lot of careful validation to get right. Software specifically developed to model floating bodies in waves would save a lot of work.

mary mor · September 20, 2013, 08:17

Thanks so much.

September 19, 2013, 13:30	simulating fluid-moored struture	#1
mary mor Member maryam morta Join Date: Sep 2013 Posts: 54 Rep Power: 12	I'm going to model a floating body(breakwater) containing air chambers which can be compressed. The floating body has mooring lines. My focus is to understand the wave diffraction of the floating body. The first question that comes to my mind is that can I generate wave in cfx? I know that it's possible to simulate the body with mooring lines in ANSYS AQWA but as far as I know, no way to simulate the air chamber. Is there any way to combine both these modules? I apprecite any help

September 19, 2013, 19:45		#3
jdrch Member Join Date: Dec 2012 Posts: 47 Rep Power: 13	AFAIK from what I've read CD-Adapco's Star-CCM+ is the leader in free surface studies. Just my 2 cents. All the best! __________________ Find me online here.

September 19, 2013, 21:12		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Let me guess - that was from a Star-CD sales guy? mary mor likes this.

September 20, 2013, 03:29		#5
mary mor Member maryam morta Join Date: Sep 2013 Posts: 54 Rep Power: 12	tanx horrock you said it's possible to do it in cfx, but I couldn't find any tutorial or option that allows modeling mooring lines in cfx. Last edited by mary mor; September 20, 2013 at 06:08.

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September 19, 2013, 18:01		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	CFX can do the model you are talking about but whether it is the most appropriate way of doing it is another question. I would ask ANSYS support about AQUA and the possibilities of combining aqua with CFX/Fluent.

September 20, 2013, 06:14		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	If you want to do simple models, like simple constraints where a rigid body is constrained to have X<some number, then this can be done in CFX. If you want more complex models with the lines modelled with weight, stretch or other more complex features I would consider linking to ANSYS or AQUA (or doing it entirely in aqua).

September 20, 2013, 07:23		#7
mary mor Member maryam morta Join Date: Sep 2013 Posts: 54 Rep Power: 12	The problem with AQWA is that as far as I know I can't model the air chamber. The air can exit from a slot opening above the chamber. This causes damping for structure displacement. consequently, it affects the wave height reflected from the body. Best regards

September 20, 2013, 07:46		#8
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	I know very little about aqua and it capabilities, but I suspect you will have much more success with this model if you use aqua and develop a air chamber model for it; rather than use a multiphase model in CFX and use FSI to get the mooring lines. The CFX model is going to very complex and will require a lot of careful validation to get right. Software specifically developed to model floating bodies in waves would save a lot of work.

September 20, 2013, 08:17		#9
mary mor Member maryam morta Join Date: Sep 2013 Posts: 54 Rep Power: 12	Thanks so much.

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