From: Timo Heister Date: Fri, 8 Oct 2021 16:11:25 +0000 (-0400) Subject: some step-49 followups X-Git-Tag: v9.4.0-rc1~950^2 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=deecc547f23f8bb580bb8ccd00fd5efe0bb76e75;p=dealii.git some step-49 followups --- diff --git a/doc/news/changes/major/20211008tjhei b/doc/news/changes/major/20211008tjhei new file mode 100644 index 0000000000..eb1eefd3e9 --- /dev/null +++ b/doc/news/changes/major/20211008tjhei @@ -0,0 +1,3 @@ +New: The step-49 tutorial now has an extended section about generating meshes from Gmsh with a more interesting example. +
+(Timo Heister, Sean Ingimarson, 2021/10/08) diff --git a/examples/step-49/doc/intro.dox b/examples/step-49/doc/intro.dox index 0212d4d016..6621fb0da6 100644 --- a/examples/step-49/doc/intro.dox +++ b/examples/step-49/doc/intro.dox @@ -1,5 +1,5 @@ This program was contributed by Timo Heister. Parts of the results section -were contributed by Yuhan Zhou, Wolfgang Bangerth, and David Wells. +were contributed by Yuhan Zhou, Wolfgang Bangerth, David Wells, and Sean Ingimarson.

Introduction

@@ -221,10 +221,17 @@ Physical Surface(2) = {1, 2, 3, 4};
Physical IDs
-This section is for assigning physical IDs as these become boundary IDs in deal.II. Here you press +This section is for assigning physical IDs as these become boundary IDs in deal.II. "Physical" object are the ones that carry information about the +boundary indicator (see @ref GlossBoundaryIndicator "this glossary entry"). +Here you press Geometry -> Physical groups -> Add -> Curve. You may do this for points as well, but we will only be needing to use curves. +@note It is important that the .geo file contains "physical lines" and "physical + surfaces". These give the boundary indicators and material ids for use + in deal.II. Without these physical entities, nothing will be imported into + deal.II. + We assign boundary ID 0 to the outer boundary. This is usually here by default but we include it anyway: @@ -310,38 +317,17 @@ Finally, we can choose Mesh -> Save to save the .msh deal.II's GridIn class can read. You can also generate the .msh from the .geo file by running the command -@code -gmsh -2 example.geo. -@endcode - -You might want to open the example.geo file in a text editor (it -is located in the same directory as the step-49.cc source file) to -see how it is structured. You can see how the boundary of the domain is -composed of a number of lines and how later on we combine several lines into -"physical lines" (or "physical surfaces") that list the logical lines' -numbers. "Physical" object are the ones that carry information about the -boundary indicator (see @ref GlossBoundaryIndicator "this glossary entry"). - -@note It is important that this file contain "physical lines" and "physical - surfaces". These give the boundary indicators and material ids for use - in deal.II. Without these physical entities, nothing will be imported into - deal.II. - -deal.II's GridIn class can read the .msh format written by -%Gmsh and that contains a mesh created for the geometry described by the -.geo file. You generate the .msh from the -.geo by running the commands - @code gmsh -2 example.geo @endcode -on the command line, or by clicking "Mesh" and then "2D" inside %Gmsh after -loading the file. Now this is the mesh read from the .msh file +Now this is the mesh read from the .msh file and saved again by deal.II as an image (see the grid_1 function -of the current program): +of the current program). - +Finally, you might want to open the example.geo file in a text editor (it +is located in the same directory as the step-49.cc source file) to +see how it is structured. @note %Gmsh has a number of other interfaces by which one can describe geometries to it. In particular, it has the ability to interface with