Are you “GUI” or “command file”?

Are you “GUI” or “command file”?

Xerox's Star workstation (1981) was the inspiration for all the other GUIs that followed (from Computer Desktop Encyclopedia)

Xerox’s Star workstation (1981) was the inspiration for all the other GUIs that followed (from Computer Desktop Encyclopedia)

A “GUI” (graphical user interface) is a type of user interface that allows users to interact with a computer program through graphical icons and visual indicators (like the windows and icons you used to reach this post).

When you click on a button, a command line is produced behind the scenes. All the Finite Element commercial software I know allows users to directly edit the command files. For example, Ansys has the powerful APDL and Comsol has Livelink.

So, why stick to the text files if you can use colorful and shiny icons? Because it’s clearer, you have more control over what the software is doing, and you end up saving time. During the design process, you change parameters here and there, and it is easy to lose control of what you are actually simulating. On the other hand, every time you run your command file, you clean up the problem and you know exactly what you are doing.

For example, take this heat sink simulation (calculated with Elmer at Idra Simulation). The definition of boundary conditions would look like this:

#  IDRA SIMULATION- Extract of Elmer command file

# all the walls at v=0
Boundary Condition 1
Name = String fluid walls;
Target Boundaries(4) = 2 3 4 5
Velocity 1 = Real 0.0
Velocity 2 = Real 0.0
Velocity 3 = Real 0.0
End

# Outlet
Boundary Condition 2
Name = String exit;
Target Boundaries(1) = 1
Pressure = Real 0.0
End

# cylindres
Boundary Condition 3
Name = String cylindres;
Target Boundaries(1) = 3

Velocity 1 = Real 0.0
Velocity 2 = Real 0.0
Velocity 3 = Real 0.0

Temperature = $TCOLD
End

# Heat Source
Body Force 2
Name = Heat Source;
Heat Source = 2.0e4
End

…pretty intuitive! And, if you want to vary a parameter, it’s easy to create a loop and sweep over different values. There’s no need to sit at your computer, manually changing them.

That said, I have nothing against GUI. I use them when I think they will save me time. My point is only that you shouldn’t be afraid of the good old command file.

heatsink_fastlight

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