Starting in the spring 2013, I videotaped the lectures for my MATH 676: Finite element methods in scientific computing course at the KAMU TV studio at Texas A&M. These are lectures on many aspects of scientific computing, software, and the practical aspects of the finite element method, as well as their implementation in the deal.II software library. Support for creating these videos was also provided by the National Science Foundation and the Computational Infrastructure in Geodynamics.

Note 1: In some of the videos, I demonstrate code or user interfaces. If you can't read the text, change the video quality by clicking on the "gear" symbol at the bottom right of the YouTube player.

Note 2: deal.II is an actively developed library, and in the course of this development we occasionally deprecate and remove functionality. In some cases, this implies that we also change tutorial programs, but the nature of videos is that this is not reflected in something that may have been recorded years ago. If in doubt, consult the current version of the tutorial.

Lecture 21.6: Boundary conditions. Part 3a: Homogenous Dirichlet boundary conditions

Strong boundary conditions (i.e., in the case of the Laplace equation, Dirichlet boundary conditions) are typically easier to understand. For users of deal.II, they are also typically easier to use because everything happens under the hood, rather than affecting the implementation of the bilinear form and/or the right hand side. At the same time, the way they are actually implemented turns out to be surprisingly complicated.

This lecture discusses the algorithms used to deal with homogenous (i.e., zero) Dirichlet boundary conditions. The algorithms are equally applicable to other strong boundary conditions, e.g., for tangential or normal flow.

Slides: click here