[Gmsh] length refinement using the box field
Shawn Fostner
sfostner at physics.mcgill.ca
Tue Jul 14 21:27:19 CEST 2009
Hi,
I've been just starting to use the the software to the point where I
think I understand what I'm doing, to a point, but using fields to
locally refine the mesh is stumping me. I have a volume defined with two
holes in it, nearby to eachother (ie within 10's of units inside of a
cube 1000 units across), and other other volume nearby. One element
being a spherical tip on something, the other a rectangular edge. The
problem is getting sufficient refinement between the two, as locally my
physical variables, electric fields in this case, vary rapidly there.
I've tried using a box field as the simplest way I can see to refine the
mesh in that region between the two, but haven't had much luck. Near as
I can tell its not doing anything at all as I vary the VIn field. I've
tried playing with the characteristic length, the internal size, the max
element size in the mesh options etc. I should note that the box is
actually overlapping two volumes, as the other volume is spatially close
by as well.
I have looked at some of the suggestions, and toyed with the other
methods for changing characteristic lengths, but without much success.
Either I can do it globally (lc in each point definition and/or max
element size), or not at all. And computationally, globally gets simply
too slow, or crashes, before I reach the point where the mesh is
sufficiently refined in the critical region.
last few lines of the geo file:
Field[1] = Box;
Field[1].VIn = lc/20;
Field[1].VOut = lc;
Field[1].XMax = -50;
Field[1].XMin = 50;
Field[1].YMax = -100;
Field[1].YMin = 50;
Field[1].ZMax = 275;
Field[1].ZMin = 350;
Background Field = 1;
Thoughts? Something blindingly obvious I'm missing?
Thanks
Shawn
--
Shawn Fostner
PhD Candidate, Physics Department, McGill University
3600 University, Montreal QC, H3A 2T8
phone: (514) 398-6749