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

CFL number and time accuracy for LES

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 19, 2002, 05:05
Default CFL number and time accuracy for LES
  #1
Li Yang
Guest
 
Posts: n/a
Dear all,

I am now doing LES using SIMPLE based solver. I use the Crank-Nicolson scheme in time and the central difference scheme in space. I would like to use the fully implicit scheme in time as well.

My questions are: (1) Which scheme would allow me to use a larger CFL number and how large a CFL number you normally used? (2) How do I know my solution is time accurate ?

Thank you very much in advance.

Li

  Reply With Quote

Old   July 28, 2002, 02:47
Default Re: CFL number and time accuracy for LES
  #2
baal
Guest
 
Posts: n/a
hello,i finished the code of les program with fortran,and i use implicit scheme,but when cfl is 1.22,the convergent rate is very small,could you help me?thanks
  Reply With Quote

Old   August 1, 2002, 06:11
Default Re: CFL number and time accuracy for LES
  #3
adarsh
Guest
 
Posts: n/a
for implicit schemes any CFL can lead you to convergence .Cfl nos up to 20 has been used.but the accuracy of solution goes down as CFL no. increases.For time accuracy u can also use jameson's method of false time stepping.

but if the samllest time scale of the flow as given by kolmogorov scales is less , the it becomes a restricting factor and convergence can be affected.

hope this helps Adarsh
  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
How to write k and epsilon before the abnormal end xiuying OpenFOAM Running, Solving & CFD 8 August 27, 2013 15:33
Multiple floating objects CKH OpenFOAM 10 September 21, 2011 23:13
Upgraded from Karmic Koala 9.10 to Lucid Lynx10.04.3 bookie56 OpenFOAM Installation 8 August 13, 2011 04:03
Unaligned accesses on IA64 andre OpenFOAM 5 June 23, 2008 10:37
IcoFoam parallel woes msrinath80 OpenFOAM Running, Solving & CFD 9 July 22, 2007 02:58


All times are GMT -4. The time now is 04:52.