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

Analysis of flow around cylinder (2D)

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

Reply
 
LinkBack Thread Tools Display Modes
Old   September 30, 2010, 13:28
Wink Analysis of flow around cylinder (2D)
  #1
New Member
 
kate
Join Date: Jul 2009
Location: iran
Posts: 29
Rep Power: 8
katiyon is on a distinguished road
Send a message via Yahoo to katiyon Send a message via Skype™ to katiyon
has anyone obtained valid hydrodynamic characteristics (Cd, Cl, St number) of a flow around circular cylinder in low Reynolds (10 -40 ) regimes by CFX? i have a 2D model and there are a lot of things that are influence on result. such as domain size and ... i cant find all
katiyon is offline   Reply With Quote

Old   September 30, 2010, 14:17
Default
  #2
Senior Member
 
Joshua Counsil
Join Date: Jul 2009
Location: Halifax, Nova Scotia, Canada
Posts: 366
Rep Power: 9
Josh is on a distinguished road
Hi Kate -

I performed a CFD analysis on a cylinder back when I was new to CFD. Naturally, the results weren't great because there were many things I didn't consider.

Two of the most important factors to consider are grid resolution (i.e., the solution doesn't change with further refinement) and grid quality (i.e., grid factors separate from resolution that affect simulation convergence). Spalart (Young-Person's Guide..., 2001) had a beautiful example of a well-resolved, high-quality grid for a cylinder. It's built for a DES simulation, but it largely encompasses the same considerations:



Avoid the overlap regions, if possible. Notice how the orthogonality, aspect ratio, skew, and other parameters are very high in quality in both the cylinder's immediate region and wake region.

Other factors are considered here:
http://www.cfd-online.com/Wiki/Ansys...gence_criteria

At that Reynolds number, you will need a laminar, unsteady solution to capture shedding.
Josh is offline   Reply With Quote

Old   February 10, 2011, 17:07
Default Hi Josh,
  #3
Senior Member
 
Ugly Kid Joe
Join Date: Aug 2010
Posts: 193
Rep Power: 7
vmlxb6 is on a distinguished road
I am trying to simulate a flow over a cylinder. Its a 1 way FSI (moving mesh problem). Your mesh is very neatly made. I need a mesh like that but finding it hard to make one. Can you tell me which software did you use to create this mesh ??? Any tutorials available ???
vmlxb6 is offline   Reply With Quote

Old   February 10, 2011, 17:57
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 11,946
Rep Power: 93
ghorrocks is a jewel in the roughghorrocks is a jewel in the roughghorrocks is a jewel in the rough
Josh included a reference in his post, that is where the mesh he showed came from.

Note the mesh is an overlaping grid. CFX does not support overlapping grids so this mesh would not be useable.

But there are hundreds of studies of flow over a cylinder in the literature using all sorts of different techniques. It is a standard benchmark simulation. Do a search of the literature and you should find lots of them.
ghorrocks is offline   Reply With Quote

Old   February 10, 2011, 20:31
Default
  #5
Senior Member
 
Joshua Counsil
Join Date: Jul 2009
Location: Halifax, Nova Scotia, Canada
Posts: 366
Rep Power: 9
Josh is on a distinguished road
I agree with Glenn. Though CFX does not support an overlapping mesh, you can still create a nice O-grid in ICEM with downstream refinement.

Here is an ICEM tutorial for creating a C-grid around an airfoil. The techniques would be similar for a cylinder.

http://www.youtube.com/watch?v=tYrbScUH9RE
Josh is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
benchmark: flow over a circular cylinder goodegg Main CFD Forum 12 January 22, 2013 12:47
flow around a cylinder pXYZ Main CFD Forum 14 July 25, 2011 10:05
Flow meter Design CD adapco Group Marketing CD-adapco 3 June 21, 2011 08:33
Flow past 2 smooth circular cylinder slip FLUENT 0 July 8, 2010 18:45
In cylinder flow analysis Venkatesh V Main CFD Forum 2 November 29, 2006 09:03


All times are GMT -4. The time now is 12:03.