From 9bb4f57b605b80eccb9ab2c709af1c8fd2133842 Mon Sep 17 00:00:00 2001 From: bangerth Date: Wed, 13 Sep 2006 19:25:28 +0000 Subject: [PATCH] Give intuitive meaning. git-svn-id: https://svn.dealii.org/trunk@13899 0785d39b-7218-0410-832d-ea1e28bc413d --- deal.II/examples/step-23/doc/intro.dox | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/deal.II/examples/step-23/doc/intro.dox b/deal.II/examples/step-23/doc/intro.dox index ec995bd1c6..98d7b63baf 100644 --- a/deal.II/examples/step-23/doc/intro.dox +++ b/deal.II/examples/step-23/doc/intro.dox @@ -374,7 +374,11 @@ R. Courant, K. Friedrichs and H. Lewy: Über die partiellen Differenzengleichungen der mathematischen Physik, Mathematische Annalen, vol. 100, no. 1, pages 32-74, 1928.) This condition on the time step is most frequently just referred -to as the CFL condition. In the program, we will refine a square +to as the CFL condition. Intuitively, the CFL condition says +that the time step must not be larger than the time it takes a wave to +cross a single cell. + +In the program, we will refine a square $[-1,1]$ seven times uniformly, giving a mesh size of $h=\frac 1{64}$, which is what we set the time step to. The fact that we set the time step and mesh size individually in two different places is error prone: it is too easy to -- 2.39.5