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-   -   moving wall (http://www.cfd-online.com/Forums/openfoam-programming-development/120037-moving-wall.html)

cctv June 28, 2013 17:59

moving wall
 
Hi
I am wondering if there is a method to move the boundary at a specified speed and change the mesh automatically in openFoam. I mean the most side wall move, not a solid body in liquid. In that case, the whole simulation domain would change, not partial domain.(something like piston moving in the vessel). I know a solver named icoDymFoam could address body moving in liquid issues, but I don't know if it could be used to simulate the situation I described above. if so, how to. If not, if there exists any other methods to fullfill it.
Thank you.

nlinder July 5, 2013 04:28

Hi,

do you know this tutorial?
Code:

OpenFOAM-2.2.x/tutorials/incompressible/pimpleDyMFoam/movingCone
Is that what you are looking for?

Greetings
Nicklas

cctv July 5, 2013 06:36

Quote:

Originally Posted by nlinder (Post 437930)
Hi,

do you know this tutorial?
Code:

OpenFOAM-2.2.x/tutorials/incompressible/pimpleDyMFoam/movingCone
Is that what you are looking for?

Greetings
Nicklas

Yes, I know this,but this is a solide body in the liquid. Not what I want. I need, for example, the inlet boundary moving.

nlinder July 5, 2013 07:14

Yes, but don't you just need to apply the pointMotionU to whatever boundary you want?

cctv July 5, 2013 08:30

Quote:

Originally Posted by nlinder (Post 437967)
Yes, but don't you just need to apply the pointMotionU to whatever boundary you want?

Yes,though the boundary moved, the result is not correct. Have you ever tried before? e.g. I want no body in liquid and the most left boundary move at a specified speed? In addition, this case is dynamic mesh with cell compressed, how about with layer addition and removal?
Thanks.

nlinder July 5, 2013 08:46

I use this procedure to move a boundary. Basically I compress the fluid between two plates. My moving boundary is a solid, but not embedded in fluid. I just thought that it would work the same way for any other boundary. I don't know what boundaries you set therefore I cannot say if it will work for your case. Also if you say the results are not correct it's difficult to help.. You need to be more precise..

Greetings

cctv July 5, 2013 12:16

1 Attachment(s)
Quote:

Originally Posted by nlinder (Post 437996)
I use this procedure to move a boundary. Basically I compress the fluid between two plates. My moving boundary is a solid, but not embedded in fluid. I just thought that it would work the same way for any other boundary. I don't know what boundaries you set therefore I cannot say if it will work for your case. Also if you say the results are not correct it's difficult to help.. You need to be more precise..

Greetings

Would you please have a look at it and see anything wrong in it?
In addition, I am wondering how to specified the motion of the boundary and is there a way to address boundary wall motion with layer addition and removal way?
Thanks.

nlinder July 9, 2013 10:49

Hi cctv,

I had a look at your case, but I do not understand what you try to do.

It is a 2D case. We have 3 boundaries:
- movingWall
- fixedWall
- farField

But if I got you right from your previous posts, you don't want to move a wall, correct? So maybe you can give me a hint what each boundary is plant to do?

Thanks
Nicklas

cctv July 10, 2013 04:15

Quote:

Originally Posted by nlinder (Post 438705)
Hi cctv,

I had a look at your case, but I do not understand what you try to do.

It is a 2D case. We have 3 boundaries:
- movingWall
- fixedWall
- farField

But if I got you right from your previous posts, you don't want to move a wall, correct? So maybe you can give me a hint what each boundary is plant to do?

Thanks
Nicklas

Hi Nicklas, I do want to move a wall, I just want to simulate a case similar to a piston moving in a vessel. as the liquid is incompressible, the fixedWall's U boundary condition, used as the outlet, is inletOutlet. Thank you.

nlinder July 10, 2013 04:36

First problem was a typo in the constant/dynamicMeshDict file

Code:

"libfvMotionSolvers.so"
correcting this, you can go on correcting the wrong/missing parts of your setup (fvSolution is missing some entries, fvSchemes as well and the pointMotion should be a vector, not a scalar). Make sure you set a totalPressure BC for the deforming walls and set the other BCs as desired (outlet or whatever).

Greetings
Nicklas

cctv July 10, 2013 05:26

Quote:

Originally Posted by nlinder (Post 438849)
First problem was a typo in the constant/dynamicMeshDict file

Code:

"libfvMotionSolvers.so"
correcting this, you can go on correcting the wrong/missing parts of your setup (fvSolution is missing some entries, fvSchemes as well and the pointMotion should be a vector, not a scalar). Make sure you set a totalPressure BC for the deforming walls and set the other BCs as desired (outlet or whatever).

Greetings
Nicklas

Thank you for your reply. there is no typo in it because what I send you is a case run in 1.6-ext. what you said is how to run in 2.1.0 or even higher version. however ,I could try it in this version. What's more, do you know how to move the wall with layer addition and removal methods? just like movingbodysolver. Thanks.

nlinder July 10, 2013 06:54

Would have been easier if you told that before...

This is what I got as a "result":
https://dl.dropboxusercontent.com/u/587565/ani.gif
(2.2.x)

About layer addition or removal I don't know much. I only used dynamicMeshRefinenemt for adding or removing cells. I don't know if the combination works as well..

Have fun

cctv July 10, 2013 13:24

Quote:

Originally Posted by nlinder (Post 438902)
Would have been easier if you told that before...

This is what I got as a "result":
https://dl.dropboxusercontent.com/u/587565/ani.gif
(2.2.x)

About layer addition or removal I don't know much. I only used dynamicMeshRefinenemt for adding or removing cells. I don't know if the combination works as well..

Have fun

Thank you very much. Could you tell me how to add or remove cells? and where is the code they map the old field into the new field?
Good luck

mturcios777 July 10, 2013 15:11

This may be of to interest to you:

http://www.cfd-online.com/Forums/ope...n-removal.html

You may have an easier time making things work as you are using 1.6-ext (I assume from previous posts). There may be a movingConeTopo mesh class; if not you will need to make your own.


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