Getting Started

Learning targets

  • Start mesh generator JCMgeo from JCMcontrol (here)
  • Start JCMgeo from the command line (console) (here)
  • Start JCMgeo within Matlab (here)
  • Start JCMgeo within Python (here)
  • Display the generated geometrical mesh using JCMview

To start with the tutorial, please unzip the archive GeoTutorial.zip. All the example files are contained within the archive in sub-folder corresponding the chapters/sections of the document.

The geometry of the “Hello World” example is a single circle in 2D. The file layout.jcm has the following simple structure:

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Layout2D {
  Objects {
    Circle { 
      Name = "MyFirstCircle"
      Radius = 1
      RefineAll = 2
    }
  }
}

We postpone the discussion of the input structure in layout.jcm to the subsequent sections. First, we demonstrate how to run JCMgeo.

JCMgeo in JCMcontrol

Open the file layout.jcm’ (placed in sub-folder `GeoTutorial/GettingStarted) within JCMcontrol by using Open from the File menu (Open Project will not work for pure meshing projects). JCMcontrol will prompt you when opening the layout.jcm file and asks, if it is to be loaded as a meshing project. The meshing project will appear in the project explorer as shown in the following figure:

_images/JCMcontrol_marked.png

GettingStarted/layout.jcm opened JCMcontrol

Click on mesh icon (red marked) to start grid generation.

The file layout.jcm appears as a project file and can be opened for editing by double-clicking. To run the mesh generation use the button marked with a red ellipse in the snapshot above. This will create the mesh file grid.jcm placed in the same directory. JCMcontrol lists this file in the Result Files section (see snapshot above). By double-clicking the mesh is shown within JCMview:

_images/JCMviewCircleMesh.png

Generated mesh shown in JCMview

JCMgeo in the command line

You can start JCMgeo from the user interface JCMcontrol or via the command line (console):

>> JCMgeo <ProjectDir>

The mesh generator JCMgeo processes the input file layout.jcm to generate a finite element mesh file grid.jcm also placed in the project directory. Use JCMview to show the generated mesh:

>> JCMview <ProjectDir>/grid.jcm

You can combine both steps by using the optional argument --show:

>> JCMgeo  <ProjectDir> --show

With the following command,

>> JCMgeo  <ProjectDir> --show <secs>

the graphic window will automatically close after <secs> seconds.

JCMgeo in Matlab

The tutorial Matlab® Interface introduces the usage of JCMsuite within Matlab in great detail. Here we want to summarize the matlab calls wrapping the above calls of JCMgeo in the console:

jcmwave_geo(<ProjectDir>); % creates mesh file <ProjectDir>/grid.jcm from layout <ProjectDir>/layout.jcm

jcmwave_view(fullfile(<ProjectDir>, 'grid.jcm')); % shows created mesh

jcmwave_geo(<ProjectDir>, [], 'show', inf); % automatically shows mesh after creation

jcmwave_geo(<ProjectDir>, [], 'show', 3); % automatically shows mesh after creation,
                                          % graphic windows closes automatically after 3 secs

JCMgeo in Python

The tutorial Python Interface introduces the usage of JCMsuite within Python is great details. Here we want to summarize the python calls wrapping the above calls of JCMgeo in the console:

jcmwave.geo('<ProjectDir>') # creates mesh file <ProjectDir>/grid.jcm from layout <ProjectDir>/layout.jcm

jcmwave.view(os.path.join('<ProjectDir>', 'grid.jcm')) # shows created mesh

jcmwave.geo('<ProjectDir>', show=float('inf')) # automatically shows mesh after creation

jcmwave.geo('<ProjectDir>',show=3) # automatically shows mesh after creation,
                                 # graphic windows closes automatically after 3 secs