dynamicMesh - move surface due to velocity/pressure

Tobi · October 27, 2014, 09:02

Hi all,

I have a question and hope that someone can help me.
The problem is very easy and we want to extend this to use it for our project.

In the attachment there is a pipe (2d). The pipe is closed and there is a fluid inside. During cooling the density is changing and therefor the outer surface of the cylinder should move inside due to pressure force. The question at the moment:

which moving solver is good for that
some links about the stuff is working would be nice
maybe there is already some project on that topic - if you know it please let me know

You are welcomed if you can give me any hints about that topic.

Kind regards
Tobi

ssss · October 27, 2014, 09:32

Are you meaning that the mesh should deform as an elastic problem? Or that your complete mesh should move?

Tobi · October 27, 2014, 10:04

Hello and thanks for your replay.
In the attachment you can find further information.

Description of the PDF

At the top you can see the fluid stored in a tank or what ever (T1, and rho1)

Due to gravity the fluid will move through the gap which is cooled

Hence the fluid cools down it changes the density (T2, rho2)

Therefor shrinkage of the volume of the fluid will occure (rho = m/V and mass conservation)

Looking to the left draft you can see a static mesh where you have the interface between fluid and air entrapment

We want to change the mesh to that curvature the fluid will get while cooling (see picture on the right)

There are several options that can be checked out:

Moving only the first cell till it reaches a defined value and then delete those cells

Moving the outer points of the surface and due to the changed position move the internal mesh too

Would be nice if someone can give me more information, lectures, projects etc.

Kind regards
Tobi

ssss · October 30, 2014, 06:23

Hi Tobi,

You're work is far beyond my knowledge, my only concern about this is that you should track the liquid fraction in the cells, once it reaches a desired level, you should delete it or at least modify it so that $\vec n = \dfrac{\nabla \gamma}{\mid \nabla \gamma \mid}$ .

Other problem would be that the boundary patch will change of cells.

I will post this so that your thread goes to the front.

Tobi · October 30, 2014, 07:38

Hi,

at the moment I made a new solver which moves the mesh due to density changing. This density changes due to temperature and the mass is conserved. Everything is working fine and I will go on with 3d mesh now and then to some curved surfaces.

wyldckat · November 1, 2014, 14:18

Quick answer/suggestion: http://openfoamwiki.net/index.php/Co...solidMechanics

October 30, 2014, 07:38		#5
Tobi Super Moderator Tobias Holzmann Join Date: Oct 2010 Location: Tussenhausen Posts: 2,708 Blog Entries: 6 Rep Power: 51	Hi, at the moment I made a new solver which moves the mesh due to density changing. This density changes due to temperature and the mass is conserved. Everything is working fine and I will go on with 3d mesh now and then to some curved surfaces. __________________ Keep foaming, Tobias Holzmann

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October 27, 2014, 09:32		#2
ssss Senior Member anonymous Join Date: Aug 2014 Posts: 205 Rep Power: 12	Are you meaning that the mesh should deform as an elastic problem? Or that your complete mesh should move?

October 30, 2014, 06:23		#4
ssss Senior Member anonymous Join Date: Aug 2014 Posts: 205 Rep Power: 12	Hi Tobi, You're work is far beyond my knowledge, my only concern about this is that you should track the liquid fraction in the cells, once it reaches a desired level, you should delete it or at least modify it so that $\vec n = \dfrac{\nabla \gamma}{\mid \nabla \gamma \mid}$ . Other problem would be that the boundary patch will change of cells. I will post this so that your thread goes to the front.

November 1, 2014, 14:18		#6
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,975 Blog Entries: 45 Rep Power: 128	Quick answer/suggestion: http://openfoamwiki.net/index.php/Co...solidMechanics