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-   -   Rigid Body motion?? (http://www.cfd-online.com/Forums/star-ccm/116785-rigid-body-motion.html)

 arun7328 April 25, 2013 04:54

Rigid Body motion??

Dear All,

I have done the boat tutorial and followed the same procedure to define DFBI for a cylinder on free surface. The fluid domain is 40x10x3 and origin of the cylinder is at 0,0. Free surface is also initialised at 0,0.

Can I impart simple harmonic oscillations to the cylinder using a field function and reference the field in the initial velocity tab of DFBI? When i do it the whole domain seems to be moving. It was done successfully using translation, morphing and overset mesh.

I also tried to define a wave at the inlet to see the free motion of the cylinder. Again the whole domain was moving.
I have created a new cartesian coordinate at 0,0 which is referenced in initial coordinate of DFBI.

Can you please give me suggestions. ?

Regards
Arun

 lava12005 April 27, 2013 11:15

I might not get your question. But if you can perform successfully with morphing/overset, then you can do the same when there is wave right?

If no morphing/overset then I believe the whole domain will move since the mesh is fixed w.r.t. the cylinder.

 arun7328 April 27, 2013 12:30

Quote:
 Originally Posted by lava12005 (Post 423523) I might not get your question. But if you can perform successfully with morphing/overset, then you can do the same when there is wave right? If no morphing/overset then I believe the whole domain will move since the mesh is fixed w.r.t. the cylinder.
Thanks a lot Lava. I was also thinking the same. Tried every possible thing i could. I thought this would work just like the boat tutorial. There the mesh is fixed to the boat, but when we it experiences an encountering wave, it heave and pitches.

I am going to a seminar by CD-adapco on tuesday will clear the doubts with them. If you have time please could you check my thread 'hydrodynamic force?' which was posted a few days back. If you have any idea could you please give me some help.

Thanks
Regards
Arun

 yanbin April 30, 2013 02:45

star ccm+

I have met the same problem. The whole domain will be moving with the DFBI module. I have been trouble for this question for two weeks.

 yanbin April 30, 2013 02:47

how can I check the mesh is fixed w.r.t. the cylinder? When generating the volume mesh, the cylinder and whole domain are meshing at the same time.

 lava12005 April 30, 2013 03:39

Hi Yanbin,

If you are not using any Overset or morphing mesh, then the whole mesh will be fixed, it means the whole domain will move with the cylinder.
Depending on what you want to achieve this is still fine (example the boat tutorial domain is moving with the boat). You just need to be careful regarding the mesh resolution at the boundary (say the free surface resolution getting worse due to the moving boundary).

There are overset and morphing tutorial, so you can see their difference.
Good luck!

 yanbin April 30, 2013 03:48

Quote:
 Originally Posted by lava12005 (Post 424088) Hi Yanbin, If you are not using any Overset or morphing mesh, then the whole mesh will be fixed, it means the whole domain will move with the cylinder. Depending on what you want to achieve this is still fine (example the boat tutorial domain is moving with the boat). You just need to be careful regarding the mesh resolution at the boundary (say the free surface resolution getting worse due to the moving boundary). There are overset and morphing tutorial, so you can see their difference. Good luck!
Thanks for your advice！I'll try and I will consult you if there are other problems.

 yanbin June 4, 2013 01:11

a fatal error has been detected by the Java Runtime Environment.

Hello. I have met a problem that the star ccm+ program exited during the running and a notepad file produced. It shows that a fatal error has been detected by the Java Runtime Environment. What's wrong with my operation for the star ccm+ program? Can you help me?

 arun7328 June 4, 2013 04:31

Do you have any msgs in your output window? Could you please elaborate a little? your problem and how you set it.

Thanks
Regards
Arun

 yanbin June 13, 2013 03:37

I'm so sorry for being late. There is a log file named "hs_err_pid720.log".
The main point of the log file is listed below,

# A fatal error has been detected by the Java Runtime Environment:
#
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x000007feed0e98af, pid=720, tid=1948
#
# JRE version: 6.0_35-b10
# Java VM: Java HotSpot(TM) 64-Bit Server VM (20.10-b01 mixed mode windows-amd64 compressed oops)
# Problematic frame:
# C [vtkCommon.dll+0x498af]
#
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.

Thanks for help

 yanbin July 9, 2013 09:05

zero acceptor cells in overset region

Hi,
Have you met the problem "zero acceptor cells in overset region" ?

Yan Bin

Quote:
 Originally Posted by arun7328 (Post 431833) Do you have any msgs in your output window? Could you please elaborate a little? your problem and how you set it. Thanks Regards Arun

 lava12005 July 9, 2013 09:44

Maybe your overset mesh has a low resolution somewhere and they meet with a high background mesh resolution?
The overset and background mesh should have similar mesh size around the intersection area..

 yanbin July 9, 2013 23:45

zero acceptor cells in overset region

Quote:
 Originally Posted by lava12005 (Post 438690) Maybe your overset mesh has a low resolution somewhere and they meet with a high background mesh resolution? The overset and background mesh should have similar mesh size around the intersection area..

 matzbanni November 13, 2013 10:15

Quote:
 Originally Posted by yanbin (Post 438794) Thank you for your advice! I am trying!

Did you solve it? I´m facing the same problem here...!

 yanbin November 14, 2013 00:42

Quote:
 Originally Posted by matzbanni (Post 461824) Did you solve it? I´m facing the same problem here...!
Yes, I have solved the problem by the advice of lava12005!

 matzbanni November 14, 2013 03:19

Found the problem as well, but it wasn't a resolution issue...

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