# Flow over a cylinder (1 way FSI)

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 LinkBack Thread Tools Display Modes
 March 4, 2011, 20:04 Flow over a cylinder (1 way FSI) #1 Senior Member   Ugly Kid Joe Join Date: Aug 2010 Posts: 193 Rep Power: 8 I know there has been tons of post on flow over a moving cylinder (transient simulation), so pardon me please. I would like to know the following: 1. what should be my mesh stiffness so that the boundary layer does not get deformed to give me weird results. 2. Right now am using a hexa structured mesh. I need to know what kind of mesh would be appropriate ??? My struct mesh gives me good results for Re = 525 but not for 200 (solution diverges). Thank you.

 March 6, 2011, 18:13 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 12,701 Rep Power: 98 A good quality structured mesh will always help, it is not the cause of the divergence at Re=200. Providing it is good quality the cause of divergence is something else.

 March 6, 2011, 18:53 #3 Senior Member   Ugly Kid Joe Join Date: Aug 2010 Posts: 193 Rep Power: 8 I have a square domain with a circle in the center. Velocity inlet to the left, Pr. outlet to the right, and velocity inlet to the top and bottom. The circle is a wall. The document you always refer us to " CFD Online ANSYS FAQ" talks about steady state convergence but not about transient convergence. Any help on that. Thank you.

 March 7, 2011, 19:56 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 12,701 Rep Power: 98 Yes, the FAQ talks about steady state but most of the same principles apply to transient. Obviously you have the additional requirement of choosing an appropriate time step size. If you are getting good convergence at Re=525 and poor at 200 then a flow feature (eg vortex shedding) is probably causing it.

 March 7, 2011, 22:08 #5 Senior Member   Ugly Kid Joe Join Date: Aug 2010 Posts: 193 Rep Power: 8 any suggestions as to what I must be doing to resolve it ???

 March 8, 2011, 17:54 #6 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 12,701 Rep Power: 98 Try smaller timesteps. For more detail you would have to post the relevant bit of the out file to diagonse the problem.

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post goodegg Main CFD Forum 12 January 22, 2013 12:47 vmlxb6 CFX 17 May 16, 2011 02:29 butch85 Main CFD Forum 3 January 31, 2011 17:10 cfdxue Main CFD Forum 0 November 27, 2007 00:26 Anna Main CFD Forum 9 March 24, 2006 15:32

All times are GMT -4. The time now is 05:59.

 Contact Us - CFD Online - Top