Hello, Geordie.
Thank you for reply.
I used "Tools - Visibility - Numeric - Mesh - Hide all elements - Show
Element (for instance, 1365)" to draw that figure.
Oh right, O.K. It's a funny looking shape, isn't it. Perhaps that's
just how Gmsh depicts nonlinear elements?
It's a very important question!
Please, look at 2 figures:
this is a shpere that was approximated by first order tets
http://saveimg.ru/show-image.php?id=47cdfa0e6f7a01f5dee8880c7081e151
this is a sphere that was approximated by second order tets
http://saveimg.ru/show-image.php?id=fa66051392be4e36e2262055272170e1
These 2 meshes was created by gmsh from one geo file (and with the same
characteristic lengths).
I will wonder if it is a feature of visualization.
Standard 10-node second order tetrahedron differs from 4-node first order
tetrahedron by adding 6 node in the middles of the edges of tetrahedron.
I think that gmsh not only adds new 6 nodes but changes the coordinates of
these nodes too.
Therefore we have nonstandard 10-node quadratic tetrahedron and the formulae
of the shape functions defined on the standard one don't work.
Am I wrong?
Mikhail Artemiev
To create the mesh I used command "gmsh mygeo.geo -3 -bin -order 2 -o
mymesh.msh", therefore following the manual the elements of the mesh are
10-node second order tetrahedra.
That's all pretty standard.
I don't know is this gmsh element a standart 10-node quadratic
tetrahedron or not.
I suppose it doesn't matter so much what Gmsh thinks as what your
finite element solver thinks? I'd say it's free to interpret Gmsh
type-11 elements as quadratic tetrahedra.
I will see the formulae. I hope that they will help me.
O.K. Let us know if you get stuck, or rather write to the list; I
think that's better in general, because others might know the answer
better or sooner than me, and also it saves it for posterity.
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