[Gmsh] (no subject)

G. D. McBain gdmcbain at protonmail.com
Mon Feb 13 01:29:31 CET 2017

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-------- Original Message --------
Subject: [Gmsh] (no subject)
Local Time: February 13, 2017 4:23 AM
UTC Time: February 12, 2017 5:23 PM
From: toddcpierce at gmail.com
To: gmsh at onelab.info

Hi All,
I am in the process of learning how to use OneLab. I have a slight grip on creating geometry and meshing and am now looking for examples of actually using GetDP. The reason I am posting this message is that I am already realizing the examples I am looking for are pretty sparse on the Internet.

There are a couple reasons they are sparse:

= What's out there is complex!! Seriously, I am a beginner here. I cannot handle something like magnetic fields. I think starting with something like the thermal conduction simulations is probably the simplest but I'm not even sure what simplicity means in this world of multi-physics simulation.

= As others may know, the whole point of my pursuing this software is for another piece of software to use it. I am therefore constrained by commands that can be piped (or typed) through the interface.cpp command line interface. So, any example that involves "clicking" here or "selecting" there is less likely to help me out in this endeavor.

Is there something like a metal bar that is hot on one end? A bar being bent? These other phenomena like magnetism and antennas look fun, but are there perhaps examples a cave person could comprehend?

Hi Todd,
A fairly simple example of solving a steady boundary value problem may be found at
https://geuz.org/trac/getdp/wiki/Capacitor2D (username: gmsh, password: gmsh)
It's expressed in terms of electrical capacitance, but if it helps it can be thought of in terms of a thermal analogy: two plates at ceiling and floor with different fixed temperatures, the space between filled with a material of one thermal conductivity except for a circular inclusion of a higher thermal conductivity. I think the left and right boundary conditions are insulated (in either the electrical or thermal interpretation).
The partial differential equation in question is Laplace's equation, which is pretty much the simplest starting place for finite element work.
I don't think I've actually run this one myself. It was back in 2010 that I was looking at it, so I'd have to dig out old notes to check. I solved the same problem in FreeFem++ using the Gmsh geometry and mesh and compared my answer with that from GetDP.

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