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#1 2015-09-29 12:28:58

m_golbs
Member
From: Germany
Registered: 2009-11-09
Posts: 126

3D_FLUIDE respectively ACOUSTIQUE for structur air interaction

Hello,

I have a question to use 3D_FLUIDE for coupled air structure interaktion.

In U3.14.02 "Modelizations 3D_FLUIDE, FLUI_STRU,
2D_FLUI_PESA" written "...structure in the presence of a nonviscous, compressible fluid".

Can I use 3D_FLUIDE only for water, oil or fuel? If it possible with Code-Aster solve coupled problems air strukture?

About informations I'm very happy.

Thanks Markus


The superfluous chase, is to miss the essential.
Jules Saliège

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#2 2015-09-29 12:50:07

RichardS
Member
From: Munich, Germany
Registered: 2010-09-28
Posts: 560
Website

Re: 3D_FLUIDE respectively ACOUSTIQUE for structur air interaction

Hello Markus,

m_golbs wrote:

If it possible with Code-Aster solve coupled problems air strukture?

Sure you can, why shouldn't you? Look for example at the test case ADLV100.
There water, air and steel are coupled.

Best,
Richard


Richard Szoeke-Schuller
Product Management
www.simscale.com
We are hiring! https://www.simscale.com/jobs/

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#3 2015-09-29 16:22:29

m_golbs
Member
From: Germany
Registered: 2009-11-09
Posts: 126

Re: 3D_FLUIDE respectively ACOUSTIQUE for structur air interaction

Hello Richard,

thanks a lot! I look in adlv100a.comm and find no real Basic different to my modell. My modell runs but the results are not true. Next I will test run without following options:
# MODELISATION='2D_FLUI_ABSO',),
# MODELISATION='2D_FLUI_PESA',),
step by step.

The boundary of air are created with ''2D_FLUI_ABSO" in step 1 and with "2D_FLUI_PESA"  in step 2. It can be a mistake.


Thanks and greeting Markus

Last edited by m_golbs (2015-09-29 16:26:36)


Attachments:
2015-09-25-ari-steel_lin_trans_50Hz.comm, Size: 6.52 KiB, Downloads: 323

The superfluous chase, is to miss the essential.
Jules Saliège

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#4 2015-09-29 19:19:26

RichardS
Member
From: Munich, Germany
Registered: 2010-09-28
Posts: 560
Website

Re: 3D_FLUIDE respectively ACOUSTIQUE for structur air interaction

Hi Markus,
just as a remark,
the 2D_FLUI_PESA elements and 2D_FLUI_ABSO are completely different elements.

2D_FLUI_PESA is used to model a free surface of a fluid and can only work if oriented normal to the z-direction of the global coordinate system (at least this was the case a few years ago).
2D_FLUI_ABSO are used to model an infinite domain by absorbing waves. In my experience they only work es expected if the waves hit the surfaces pretty parallel if not you will still have reflections.

Best,
Richard

Last edited by RichardS (2015-09-29 19:20:04)


Richard Szoeke-Schuller
Product Management
www.simscale.com
We are hiring! https://www.simscale.com/jobs/

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#5 2015-09-30 09:04:24

m_golbs
Member
From: Germany
Registered: 2009-11-09
Posts: 126

Re: 3D_FLUIDE respectively ACOUSTIQUE for structur air interaction

Hello Richard,

thanks a lot! "... 2D_FLUI_PESA elements and 2D_FLUI_ABSO are completely different elements.
" Thats know, but I was test the effects of this different types of element.

Ambition behind 2D_FLUI_PESA or 2D_FLUI_ABSO are the nonreflecting or semiinfinite space. How can I create this type of elements in Code-Aster?
The 2D_FLUI_ABSO are not nonreflecting?

My first mistake are:

# 2D_FLUI_PESA oriented normal to the z-direction of the global coordinate system, my mesh of group PESA are spherical shape and all normals not z-direction.

Thanks and greating Markus


The superfluous chase, is to miss the essential.
Jules Saliège

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#6 2015-10-04 17:45:06

CLF
Member
From: Sweden
Registered: 2009-01-27
Posts: 136
Website

Re: 3D_FLUIDE respectively ACOUSTIQUE for structur air interaction

Hi Markus

The PESA element is a free surface element, e.g. to capture pretensioning of water surfaces etc.

The acoustics open ended boundary condition is far from easy to find. It took me a while & Yes, I did also use the PESA element at first.

The way to get a free acoustic boundary condition is to set PHI = 0 at the free boundary. 

The PHI variable is not intuitive and is simplest to understand as acoustic particle displacement, se document R4.02.02, chapter 2.6.

Hope this helps
Claes

Last edited by CLF (2015-10-04 21:44:48)

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