CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

Time based rotating condition

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree1Likes
  • 1 Post By ghorrocks

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   October 30, 2023, 07:37
Default Time based rotating condition
  #1
New Member
 
Rakeshchandra
Join Date: Jul 2020
Posts: 13
Rep Power: 5
Rakeshchandra is on a distinguished road
I'm trying to simulate a butterfly damper opening and closing condition for reference but i'm unable to write a condition such that the damper stops rotating when rotated to 90deg.
Rakeshchandra is offline   Reply With Quote

Old   October 30, 2023, 17:50
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,771
Rep Power: 143
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
There are many ways of doing this:

1) Rotating frame of reference: I suspect this is how you have done it. It is simple and easy to implement and computationally cheap, but you cannot control the rotation beyond a constant velocity.

2) Moving mesh with one domain: This is difficult to implement as the large deformation will make it difficult to deform the mesh and not fold it. I would not recommend this.

3) Moving mesh with two domains: This uses a similar mesh setup to the rotating frame of reference approach, but instead of using a rotating frame of reference to move the butterfly you use moving mesh. This is much more computationally expensive than RFR, but it does give you complete control over the motion.

I suspect you will find option 3 as the most viable option.
__________________
Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.
ghorrocks is offline   Reply With Quote

Old   October 30, 2023, 21:58
Default
  #3
New Member
 
Rakeshchandra
Join Date: Jul 2020
Posts: 13
Rep Power: 5
Rakeshchandra is on a distinguished road
Thanks for replying, I'm aware of these methods and I was successful to run it but i'm unable to stop rotation. I've provide angular velocity of 0.157 rad/s and I need to stop it's rotation at time of 10sec where the over all simulation is for 45sec. I tried using defining functions to halt it's rotation but wasn't successful. The function that I wrote is:

tt = 45s
dt = 0.25 s
halt = if(tt >= 5 [s], 0 [radian s^-1], 0.15708 [radian s^-1]

IDK where i'm doing wrong.
Rakeshchandra is offline   Reply With Quote

Old   October 31, 2023, 04:49
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,771
Rep Power: 143
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Let me repeat:

Quote:
you cannot control the rotation beyond a constant velocity.
So you cannot change the angular velocity during a run.

You have to use option 3 so you can change the angular velocity in a run.
Rakeshchandra likes this.
__________________
Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.
ghorrocks is offline   Reply With Quote

Old   October 31, 2023, 05:08
Default
  #5
New Member
 
Rakeshchandra
Join Date: Jul 2020
Posts: 13
Rep Power: 5
Rakeshchandra is on a distinguished road
oh thanks for clarifying, I didn't find much references regarding moving the mesh while running could you please share any references of the case.
Rakeshchandra is offline   Reply With Quote

Old   October 31, 2023, 16:38
Default
  #6
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,771
Rep Power: 143
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
There are a few tutorial examples which use it, and it is described in the CFX documentation.
__________________
Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.
ghorrocks is offline   Reply With Quote

Reply

Tags
ansys 14, cfx & stator & rotor, cfx 15, moving 3d mesh, moving boundary

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
How to export time series of variables for one point? mary mor OpenFOAM Post-Processing 8 July 19, 2017 10:54
High Courant Number @ icoFoam Artex85 OpenFOAM Running, Solving & CFD 11 February 16, 2017 13:40
Star cd es-ice solver error ernarasimman STAR-CD 2 September 12, 2014 00:01
Moving mesh Niklas Wikstrom (Wikstrom) OpenFOAM Running, Solving & CFD 122 June 15, 2014 06:20
How to write k and epsilon before the abnormal end xiuying OpenFOAM Running, Solving & CFD 8 August 27, 2013 15:33


All times are GMT -4. The time now is 01:17.