|January 13, 2012, 09:28||
Breaking of constraint conditions
Join Date: Nov 2011
Posts: 8Rep Power: 7
I've faced a very strange problem while trying to calculate the 2DoF movement of a cuboid in a canal with interDyMFoam. Cuboid is half submerged in water and the inflow velocity in longitudinal direction ( X ) is 0.5 m/s. I use the constraint fixedLine in the vertical ( Z ) direction ( not to let the cuboid move downstream the canal ) and fixedAxis around Y-axis ( to let only the trim change ).
For some time the constraint condition is satisfied, but after 2-3 seconds of model time, the object starts shifting downstream the canal ( along the X-axis ), and the shifting velocity is quite large. I see this movement in Paraview, but when I look at the log it reports that the body is moving not in the X-direction but in Z direction ( ! ).
So, there are two questions:
1. Why the constraint condition is not satisfied after some time?
2. Why the log and the actual mesh movement ( in Paraview ) do not coincide.
I use OpenFOAM 2.1.x, but this behavior can be seen in earlier versions too.
I tried to make the same simulation in OF 1.6 ext , but it gave the similar result.
I also tried using different constraint combinations, varying the relaxation factor and tolerance - still no effect.
The only way I've found to reduce this movement is to increase the inertia moments ( ! ) ( But I can not understand, how they are connected. )
Has anybody faced such problems?
Last edited by lt.quibbler; January 16, 2012 at 12:53.
|Thread||Thread Starter||Forum||Replies||Last Post|
|Wind turbine simulation||Saturn||CFX||45||February 8, 2016 05:42|
|Implementation of boundary conditions for FVM||Tom||Main CFD Forum||7||August 26, 2014 05:58|
|Water subcooled boiling||Attesz||CFX||7||January 5, 2013 04:32|
|Boundary conditions?||Tom||Main CFD Forum||0||November 5, 2002 02:54|
|A problem about setting boundary conditions||lyang||Main CFD Forum||0||September 19, 1999 18:29|