From f0dd458b1fe9c2c0e07339dcf351996b15a5e5f8 Mon Sep 17 00:00:00 2001 From: bangerth Date: Mon, 22 Sep 2008 02:03:55 +0000 Subject: [PATCH] Comment on boundary conditions. git-svn-id: https://svn.dealii.org/trunk@16891 0785d39b-7218-0410-832d-ea1e28bc413d --- deal.II/examples/step-31/doc/intro.dox | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/deal.II/examples/step-31/doc/intro.dox b/deal.II/examples/step-31/doc/intro.dox index 068e63a36a..783a4e5c5c 100644 --- a/deal.II/examples/step-31/doc/intro.dox +++ b/deal.II/examples/step-31/doc/intro.dox @@ -946,9 +946,13 @@ The case we want to solve here is as follows: we solve the Boussinesq equations described above with $\kappa=1, \eta=1, \mathrm{Ra}=10$. On the boundary, we will require no-normal flux for the velocity ($\mathrm{n}\cdot\mathrm{u}=0$) and for the temperature -($\mathrm{n}\cdot\nabla T=0$). No boundary conditions are required for the -pressure under these conditions. Initial conditions are only necessary for the -temperature field, and we choose it to be constant zero. +($\mathrm{n}\cdot\nabla T=0$). This is one of the cases discussed in the +introduction of @ref step_22 "step-22" and fixes one component of the velocity +while allowing flow to be parallel to the boundary. There remain +dim-1 components to be fixed, namely the tangential components of +the normal stress; for these, we choose homogenous conditions which means that +we do not have to anything special. Initial conditions are only necessary for +the temperature field, and we choose it to be constant zero. The evolution of the problem is then entirely driven by the right hand side $\gamma(\mathrm{x},t)$ of the temperature equation, i.e. by heat sources and -- 2.39.5