[Gmsh] Controlling Mesh Size in GUI

[Rudin, Andrew]

Okay, I see how to modify the mesh size by editing variable in the.geo file, reload geometry in the GUI, and then rebuild the mesh.

Thank you so much.

-----Original Message-----
From: gdmcbain at gmail.com [mailto:gdmcbain at gmail.com] On Behalf Of Geordie McBain
Sent: Monday, December 12, 2011 9:34 PM
To: Rudin, Andrew
Cc: gmsh at geuz.org
Subject: Re: [Gmsh] Controlling Mesh Size in GUI

2011/12/13 Rudin, Andrew <Andrew.Rudin at austintexas.gov>:
> I'm new to Gmsh and I'm trying to learn the basics from the GUI interface.
> I'm trying to play with building a 2-D mesh on a simple box and then 
> inspect the output as I change mesh parameters.  I'm trying to 
> manipulate the average size of each triangle in the mesh, but the output is not changing.
> Here's some of the things I've tried.
>
> -Open 2.5 GUI
> -Add 4 points at [0,0], [100,0], [100,100], and [0, 100] -Draw lines 
> between the points to create a square -Create planar surface from 
> lines.
> -Create 2D mesh by going to Mesh->2D
>     -a basic mesh is created, average triange area appears to be about 
> 1 square units of a 10,000 square unit box
>
> Here's the problem.  Now I want to control the size and dicate every 
> triangles area should be about 100 square units.
>
> -Set mesh 'element size factor' to 100 by going to
> Tools->Options->Mesh->Change element size factor to 100, then on the 
> Tools->Options->Mesh->main
> Gmsh GUI go to Mesh->2D to rebuild
>
> After this the mesh does not seem to resize to have bigger triangles

Hello.  I'm sure there is a way to do this in the GUI, but I only really use the script input myself; here's how to do it that way.

Running the attached size.geo produces 28 elements, then editing the first line to reduce lc to 10 and then 1 produces instead 286 and 26900 elements.