dolfin team mailing list archive

[Marie Rognes <663250@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

Something slightly peculiar seems to happen with 3d refinement. Refining
a 1 x 1 x 1 Unit Cube 3 times gives largest cell diameter that is
increasing (but smallest cell diameter  that is decreasing as expected).
It does not seem to (only) be a bug in hmax()/hmin(), odd convergence
rates are also observed. 
Example:

from dolfin import *

mesh = UnitCube(1, 1, 1)

for i in range(3):
    mesh = refine(mesh)

    print "Refinement level = ", i
    print "h_max = ", mesh.hmax()
    print "h_min = ", mesh.hmin()

gives:

Refinement level =  0
h_max =  1.65831239518
h_min =  0.866025403784
Refinement level =  1
h_max =  1.47901994577
h_min =  0.433012701892
Refinement level =  2
h_max =  1.7809758561
h_min =  0.216506350946

** Affects: dolfin
     Importance: High
     Assignee: Anders Logg (logg)
         Status: Confirmed

-- 
3D mesh refinement gives strange mesh sizes
https://bugs.launchpad.net/bugs/663250
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Status in DOLFIN: Confirmed

Bug description:
Something slightly peculiar seems to happen with 3d refinement. Refining
a 1 x 1 x 1 Unit Cube 3 times gives largest cell diameter that is
increasing (but smallest cell diameter  that is decreasing as expected).
It does not seem to (only) be a bug in hmax()/hmin(), odd convergence
rates are also observed. 
Example:

from dolfin import *

mesh = UnitCube(1, 1, 1)

for i in range(3):
    mesh = refine(mesh)

    print "Refinement level = ", i
    print "h_max = ", mesh.hmax()
    print "h_min = ", mesh.hmin()

gives:

Refinement level =  0
h_max =  1.65831239518
h_min =  0.866025403784
Refinement level =  1
h_max =  1.47901994577
h_min =  0.433012701892
Refinement level =  2
h_max =  1.7809758561
h_min =  0.216506350946