Hemisphere-point loads

Numerical methods and mathematical models of Elmer
mika
Posts: 230
Joined: 15 Sep 2009, 07:44

Re: Hemisphere-point loads

Post by mika »

Hi,
spolanski wrote: 19 Mar 2021, 15:41 I see a lot of warnings:

WARNING:: LinesOfCurvatureFrame: Possibly very rough geometry model used

which is very strange because the mesh looks almost the same as the one used by kevinarden. Additionally to that, the results are not correct.
Hi,

I eventually had time to look at this trouble. If you now compile Elmer from fresh source files (Apr 20, 2021) and add a command Spherical Body = True to the body section, the shell solver runs quietly and produces the displacements

UX = 1.849E-1
UY = -1.849E-1

at the points where the loads are applied. I used the file mesh.director you attached.
with_spherical_body.png
(371.64 KiB) Not downloaded yet
Some explanations:

This mesh has elements with high aspect ratios and this may cause troubles here. The shell solver creates a local reparametrization by lines of curvature coordinates and this procedure needs to place a regular grid within each element to estimate curvatures. Fitting such a grid can be problematic for very high aspect ratios. The keyword Spherical Body = True now gives additional guidance for the reparametrization subroutine so that the shell solver doesn't try decide spherical regions by a computational criterion. Of course a good solver should be automatic and shouldn't need such additional information about the geometry. It seems that at the moment giving this information may however lead to much better results if the mesh is not regular.

The modified sif file is attached.

Best regards,
Mika
Attachments
myversion.sif
(1.86 KiB) Downloaded 144 times
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