
[Sponsors] 
June 17, 2018, 02:15 

#21  
Senior Member
Join Date: Mar 2015
Posts: 892
Rep Power: 17 
Quote:
As you have already determined, the position is consistent after restarting Fluent, but what about ? 

June 17, 2018, 02:19 

#22  
Member
Join Date: Sep 2016
Posts: 43
Rep Power: 9 
Quote:
Please don't go out of your way to do this but. If you have some time to kill only then do it cos it will take a day easily. That was very kind of you to offer to simulate it yourself. 

June 17, 2018, 02:20 

#23 
Member
Join Date: Sep 2016
Posts: 43
Rep Power: 9 

June 17, 2018, 02:24 

#24 
Senior Member
Join Date: Mar 2015
Posts: 892
Rep Power: 17 
I have not used the Six DOF solver before, and I do not have this version of ANSYS installed to have a quick check. Is there any mention in the Fluent guides? Otherwise have a look around the GUI?


June 17, 2018, 02:30 

#25 
Member
Join Date: Sep 2016
Posts: 43
Rep Power: 9 
Yea, will do that. I have restarted a simulation for another case to see if this happens in that too. If it does, then next time I will use the UDF approach. But honestly, I would expect the same thing to happen there too cos the UDF will only have the mass, spring constant and 1dof as parameters, not initial equilibrium position.


June 17, 2018, 02:47 

#26  
Senior Member
Join Date: Mar 2015
Posts: 892
Rep Power: 17 
Quote:
If you only want a single DOF such that the restoring force of the spring acts purely in the ydirection, then the force on the cylinder could be calculated with: Code:
force = k*(DT_CG(dt)[1]  x_equilibrium[1]); Note: remember that indexing in C starts from zero instead of one, so DT_CG(dt)[1] corresponds to the second spatial coordinate (y for Cartesian). 

June 17, 2018, 02:51 

#27 
Member
Join Date: Sep 2016
Posts: 43
Rep Power: 9 
Quote:


June 17, 2018, 04:36 

#28  
Member
Join Date: Sep 2016
Posts: 43
Rep Power: 9 
Quote:


June 17, 2018, 04:53 

#29 
Senior Member
Join Date: Mar 2015
Posts: 892
Rep Power: 17 
Well, this result is consistent with what we consider the problem to be: that the equilibrium position of the spring is being reset on restarting Fluent. I would expect (or at least hope) that using the UDF would solve this issue, and would also give you greater control and transparency on what you are actually solving.
Yes, a 3D simulation would be much more computationally expensive. Remember to optimise your mesh and you could also start with an initial condition based on your 2D result to help reduce the time it takes for the flow/oscillations to fully develop. 

June 17, 2018, 05:02 

#30  
Member
Join Date: Sep 2016
Posts: 43
Rep Power: 9 
Quote:


June 19, 2018, 07:50 

#31 
Member
Join Date: Sep 2016
Posts: 43
Rep Power: 9 
Quote:


March 4, 2021, 01:37 

#32 
New Member
Join Date: Nov 2020
Posts: 5
Rep Power: 5 

Tags 
dynamic mesh, restart problem, viv 
Thread Tools  Search this Thread 
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
decomposePar problem: Cell 0contains face labels out of range  vaina74  OpenFOAM PreProcessing  37  July 20, 2020 06:38 
Local mesh refinement definition in a DEFORMING dynamic mesh zone using Dynamic Mesh  Emanuele88  FLUENT  0  February 9, 2016 12:39 
[mesh manipulation] Importing Multiple Meshes  thomasnwalshiii  OpenFOAM Meshing & Mesh Conversion  18  December 19, 2015 19:57 
Dynamic mesh simulation (pimpleDyMFoam) problem  sidlof  OpenFOAM Running, Solving & CFD  6  April 12, 2013 12:24 
CFD3D flow problem using Dynamic mesh method.  Sar_mech  FLUENT  1  November 27, 2008 22:17 