# CrankNicolson discretization and Courant number

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

 February 8, 2015, 07:08 CrankNicolson discretization and Courant number #1 Senior Member   Join Date: Jan 2015 Posts: 150 Rep Power: 9 in book it's written that CrankNicolson method is unconditionally stable. But using this method in icoFoam solver my solution after ~100 iterations explodes... Courant number is >60 at start and increasing (because I have an increasing transient inlet velocity). Yes, Courant number is big, but as I said before CrankNicolson method is unconditionally stable.. So what a problem with simulation ?? Maybe someone got such problem before.

 February 8, 2015, 09:00 #2 Senior Member   Alexey Matveichev Join Date: Aug 2011 Location: Nancy, France Posts: 1,930 Rep Power: 36 Hi, For what type of equations it is unconditionally stable (see the book)?

 February 8, 2015, 09:29 #3 Senior Member   Join Date: Jan 2015 Posts: 150 Rep Power: 9 According to "Introduction to Computational Fluid Dynamics" 2nd edition" it is written "...schemes with – 1 2 ≤ θ ≤ 1, including the Crank–Nicolson scheme, are unconditionally stable for all values of the time step" ...

November 15, 2019, 08:30
#4
Senior Member

Jianrui Zeng
Join Date: May 2018
Location: China
Posts: 157
Rep Power: 6
Quote:
 Originally Posted by Svensen According to "Introduction to Computational Fluid Dynamics" 2nd edition" it is written "...schemes with – 1 2 ≤ θ ≤ 1, including the Crank–Nicolson scheme, are unconditionally stable for all values of the time step" ...
I am still confused about the instability of CrankNicolson 0.9. Any suggestion?

 Tags crank-nicolson, icofoam, openfoam 2.3.0

 Thread Tools Search this Thread Search this Thread: Advanced Search 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 Off Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post mlawson OpenFOAM 11 November 29, 2014 10:37 wc34071209 OpenFOAM Running, Solving & CFD 16 March 9, 2014 19:31 fsaltara OpenFOAM 8 December 28, 2012 04:16 mrshb4 OpenFOAM 0 December 13, 2010 11:13 msrinath80 OpenFOAM Running, Solving & CFD 1 May 29, 2006 17:20

All times are GMT -4. The time now is 03:04.

 Contact Us - CFD Online - Privacy Statement - Top