CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > Siemens > STAR-CCM+

Flapping foil displacement in wrong direction?

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 29, 2017, 00:56
Default Flapping foil displacement in wrong direction?
  #1
New Member
 
Anties K Martin
Join Date: Aug 2016
Location: chennai
Posts: 16
Rep Power: 9
antieskmartin is on a distinguished road
Hello all

when I was simulating the foil alone(open water

condition) which undergoes both translation and rotation. I have noticed that

the foil is slowly moving in the X direction(where x direction motion is

restricted). Actually, I have confused why it is happening. At the

start of the simulation both the lab and managed coordinates are at the

same point.

After iterating it seems there is slight change in the position of managed

coordinates while the lab coordinate is at the same location. Thus it causes

the foil to move out of the overlap region. I am attaching

the link of images

1.initial foil image.
https://antieskmartin.blogspot.com/2...tial-foil.html

2.foil after simulation.
https://antieskmartin.blogspot.com/2...imulation.html

3.Motion details
https://antieskmartin.blogspot.com/2...n-details.html


Could you please help me in figuring out the problem.

Thanks in advance.
antieskmartin is offline   Reply With Quote

Old   August 29, 2017, 06:34
Default
  #2
Senior Member
 
ashokac7's Avatar
 
Ashok Chaudhari
Join Date: Aug 2016
Location: Pune, India
Posts: 260
Rep Power: 10
ashokac7 is on a distinguished road
Send a message via Skype™ to ashokac7
Hard to understand you problem from given data. I had once face such situation. problem was with the co-ordinate system itself.
ashokac7 is offline   Reply With Quote

Old   August 29, 2017, 07:12
Default
  #3
New Member
 
Anties K Martin
Join Date: Aug 2016
Location: chennai
Posts: 16
Rep Power: 9
antieskmartin is on a distinguished road
Thank You, Ashok for you reply

Let me explain the problem briefly.

In the beginning, I choose two coordinate system where one is stationary other

is managed one. The foil is allowed to oscillate only in the Z direction. But I

found that after every oscillation the foil is moving slightly in the X direction. I

Can't figure out this error. Could you help me to rectify this?

Thanks in advance.
antieskmartin is offline   Reply With Quote

Old   August 29, 2017, 15:42
Default
  #4
New Member
 
Paresh
Join Date: Jun 2017
Location: Austria
Posts: 27
Rep Power: 8
pary07 is on a distinguished road
Hi,
The problem as to be with the coordinate system as ashok has stated. The managed coordinate that you have mentioned with respect to which the foil is moving is probably aligned incorrect. Try to do manual translation in the geometry by giving some input and check if the new translated location is aligned with its original position. How exactly have you created the managed co-ordinate system ?
Also, I cannot see the images that you have linked.
pary07 is offline   Reply With Quote

Old   August 30, 2017, 03:45
Default
  #5
New Member
 
Anties K Martin
Join Date: Aug 2016
Location: chennai
Posts: 16
Rep Power: 9
antieskmartin is on a distinguished road
Dear Paresh

Thanks for your reply

Here I am attaching the images
Attached Images
File Type: png Initial.PNG (5.1 KB, 11 views)
File Type: png Foil.PNG (18.3 KB, 10 views)
antieskmartin is offline   Reply With Quote

Old   August 30, 2017, 06:00
Default
  #6
New Member
 
Anties K Martin
Join Date: Aug 2016
Location: chennai
Posts: 16
Rep Power: 9
antieskmartin is on a distinguished road
Dear Paresh

Thanks for your reply

Here I am attaching the images
antieskmartin is offline   Reply With Quote

Old   September 1, 2017, 02:17
Default
  #7
Senior Member
 
Ping
Join Date: Mar 2009
Posts: 556
Rep Power: 20
ping is on a distinguished road
i see in your motion setting that you have both the translation and rotation in the one motion and this is not correct for what you have asked for and clearly explains why you have the unwanted x motion
you need to first have just a translation motion and then superimposed on top of that motion you add the rotation as a new motion node feature as i explained in my other long post. this motion with be in a coordinate system that moves with the z motion ie a new one managed by the z motion
i would first just get the simple translation working with managing a coordinate system and ignore rotation and if that does not do what you want then you have a more basic issue
ping is offline   Reply With Quote

Reply

Tags
biomimetics, cfd analysis, flapping foil propulsion, overset problem

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
udf error srihari FLUENT 1 October 31, 2016 14:18
Flow Direction: normal to boundary!!! Atit CFX 1 August 2, 2015 13:42
[ICEM] Wrong Prism Direction max3.2 ANSYS Meshing & Geometry 7 August 20, 2011 20:09
specified displacement didn't correspond Smagmon CFX 0 February 13, 2009 09:41
[Commercial meshers] Trimmed cell and embedded refinement mesh conversion issues michele OpenFOAM Meshing & Mesh Conversion 2 July 15, 2005 04:15


All times are GMT -4. The time now is 18:05.