In many cases when we create a geometry, it is often useful to name certain parts of the geometry using terminology that we are familiar with. This can already be done in ParaGeo work flow when we use Geometry_set. In Gmsh, this is done by using Physical groups.

 

Using the cube geometry as an example, we aim to define physical groups as follow:

 

We start by selecting Geometry -> Physical Groups -> Add -> Surface.

 

 

We first enter the name in the dialog box, choose the corresponding surface, and press e to end selection.

 

 

The name in the dialog box will turn into red, indicating that this name is already registered and shall not be used. Repeat the same procedure to name all other surfaces (e.g. East, South, North, Bottom, and North). Finally, press “q” to abort.

 

We now check if the names are registered successfully by selecting Tools->Visibility.

 

Now, if we want to show only East and South surfaces, we simply select them and hit “Apply” button.