CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > General Forums > Main CFD Forum

DNS of Re 3900 cylinder flow

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 30, 2013, 13:01
Default DNS of Re 3900 cylinder flow
  #1
Senior Member
 
cfdnewbie
Join Date: Mar 2010
Posts: 557
Rep Power: 20
cfdnewbie is on a distinguished road
Hello fellow researchers,
I'm looking for DNS results of the standard RE 3900 cylinder test case. I have done a literature search on this topic, and the "largest" DNS I found is in here: http://www.cfm.brown.edu/people/gk/jfm_re10K.pdf (with a reference to a paper by Ma with a similar resolution). Do you happen to know of any more recent DNS of this flow, preferably with a higher resolution? I'm looking for the best reference possible for this case, and I am trying to judge whether it is worthwile doing a higher resolution DNS of this flow.
Thanks a lot, have a great weekend!
cfdnewbie is offline   Reply With Quote

Old   May 30, 2013, 15:04
Default
  #2
Far
Super Moderator
 
Sijal
Join Date: Mar 2009
Location: Islamabad
Posts: 4,553
Blog Entries: 6
Rep Power: 54
Far has a spectacular aura aboutFar has a spectacular aura about
Send a message via Skype™ to Far
Mesh in journal paper is too coarse
Far is offline   Reply With Quote

Old   May 30, 2013, 15:53
Default
  #3
Senior Member
 
cfdnewbie
Join Date: Mar 2010
Posts: 557
Rep Power: 20
cfdnewbie is on a distinguished road
Do you have a recommendation for what the mesh should look like? Why do you think the mesh in the paper is too coarse?
cfdnewbie is offline   Reply With Quote

Old   May 30, 2013, 16:05
Default
  #4
Far
Super Moderator
 
Sijal
Join Date: Mar 2009
Location: Islamabad
Posts: 4,553
Blog Entries: 6
Rep Power: 54
Far has a spectacular aura aboutFar has a spectacular aura about
Send a message via Skype™ to Far
1. It should be hexa/map mesh

2. It should follow DX, DY and DZ requirements of DNS mesh
Far is offline   Reply With Quote

Old   May 30, 2013, 16:11
Default
  #5
Senior Member
 
cfdnewbie
Join Date: Mar 2010
Posts: 557
Rep Power: 20
cfdnewbie is on a distinguished road
Quote:
Originally Posted by Far View Post
1. It should be hexa/map mesh
hm, why would you say that? there are two in the paper. One is on hexas, the other on tetras. As long as the resolution is close to a DNS, it doesn't make a difference.
Quote:
2. It should follow DX, DY and DZ requirements of DNS mesh
It seems that the resolution they are using does that, doesn't it? They have a grid point at 0.32 based on the friction velocity...that sounds sufficient to me, or am I misunderstanding somehting?

The only thing that bothers me somewhat is that they use only about 14mio of DOF for this case...that seems not too much for today's standards, but of course that was in 2000....
cfdnewbie is offline   Reply With Quote

Old   May 30, 2013, 16:13
Default
  #6
Far
Super Moderator
 
Sijal
Join Date: Mar 2009
Location: Islamabad
Posts: 4,553
Blog Entries: 6
Rep Power: 54
Far has a spectacular aura aboutFar has a spectacular aura about
Send a message via Skype™ to Far
There are two meshes. One is low resolution tetra and second is high resolution tetra
Far is offline   Reply With Quote

Old   May 30, 2013, 16:19
Default
  #7
Senior Member
 
cfdnewbie
Join Date: Mar 2010
Posts: 557
Rep Power: 20
cfdnewbie is on a distinguished road
The second tetra (9272 elems) has about 24mio grid points, the second hex mesh they are talking about has less than that (about 14mio). So the highest number of DOF is indeed 24 mio, which seems to me not too much for a DNS - and certainly easily surpassed with today's codes.
cfdnewbie is offline   Reply With Quote

Old   May 30, 2013, 16:26
Default
  #8
Far
Super Moderator
 
Sijal
Join Date: Mar 2009
Location: Islamabad
Posts: 4,553
Blog Entries: 6
Rep Power: 54
Far has a spectacular aura aboutFar has a spectacular aura about
Send a message via Skype™ to Far
Quote:
Originally Posted by cfdnewbie View Post
The second tetra (9272 elems) has about 24mio grid points, the second hex mesh they are talking about has less than that (about 14mio). So the highest number of DOF is indeed 24 mio, which seems to me not too much for a DNS - and certainly easily surpassed with today's codes.
Could you please explain what is meant by 9272 elements and how it is equivalent to 24 million grid points.
Far is offline   Reply With Quote

Old   May 30, 2013, 16:30
Default
  #9
Senior Member
 
cfdnewbie
Join Date: Mar 2010
Posts: 557
Rep Power: 20
cfdnewbie is on a distinguished road
They are using a 5th order Jacobian basis in each hex. Most likely, that's 6*7/2 DOFs per element, at least that's the standard approach on tets. So each 2D plane has about 9000 * 21 = 189000 DOF. Times the Fourier nodes (128), thats about 24 mio.
cfdnewbie is offline   Reply With Quote

Reply

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
flow around a cylinder pXYZ Main CFD Forum 14 July 25, 2011 11:05
1 Was FSI for a flow over a cylinder vmlxb6 CFX 17 May 16, 2011 03:29
reference calcultion, flow around a cylinder butch85 Main CFD Forum 3 January 31, 2011 17:10
Flow past cylinder (Re=10^5) lbeaudet Main CFD Forum 9 June 2, 2009 04:59
Flow around a cylinder at subcritical regime. yousef FLUENT 0 March 18, 2006 10:18


All times are GMT -4. The time now is 04:04.