[Gmsh] Characteristic length

[Andres Gonzalez Estrada]

Does anyone have a clue about how gmsh interpret the characteristic lenght?. The problem has been described before in several post with no successful reply, e.g.:

*Jö Fahlke*  
     jorrit at jorrit.de  <mailto:gmsh%40geuz.org?Subject=Re%3A%20%5BGmsh%5D%20Characteristic%20length&In-Reply-To=%3C20110214153108.GZ1523%40paranoia%3E>

     /Mon Feb 14 16:31:08 CET 2011/

I can think of several meanings for "characteristic length" (or "elements
size" for that matter):

  * The length of the mesh elements' edges,
  * the cubic root of the mesh elements' volume,
  * the diameter of the circumscribed sphere of the mesh elements, or
  * the radius of the circumscribed sphere of the mesh elements.

There are probably more possibilities.  What I want to know is whether gmsh
follows a one consistent meaning for the characteristic length, and if yes,
which one.

(More accurately, I want to limit the edge sizes in the grid, an I suspect the
characteristic length can be used for that, but I can't figure out how
exactly.  The obvious approach of "max characteristic length" == "max edge
size" did not work, see my first mail.)

Am Mon, 14. Feb 2011, 15:49:58 +0100 schrieb David Colignon:
>/  do a search with the keyword "characteristic" on this page:https://geuz.org/gmsh/doc/texinfo/gmsh.html
/>/  
/>/  and/or seehttp://geuz.org/gmsh/doc/texinfo/gmsh.html#Specifying-mesh-element-sizes
/
I did, but I could not find an answer to the above question.  The closest to
an explanation of the meaning of the characteristic length was

|/  Every meshing step is constrained by a "size field" (sometimes called
/|/  "characteristic length field"), which prescribes the desired size of the
/|/  elements in the mesh.
/
(from section 1.2 "Mesh: finite element mesh generation"), which links the
characteristic length to the mesh element size, but does not explain how the
mesh element size is measured or how exactly it is linked to the
characteristic length.

Thanks,
Jö.

-- 
--
Octavio Andrés González Estrada
Research Associate
Institute of Mechanics and Advanced Materials
Cardiff School of Engineering
Cardiff University
The Parade
Cardiff CF24 3AA, Wales, UK

Email: agestrada at gmail.com
        estradaoag at cardiff.ac.uk

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