GiD forum

Hello,

I am building a 3D model of a beam with a 45 degree slot in the middle. The tetrahedral mesh that I would like to build is an unstructured one, with smaller elements in the middle (close to the slot) and bigger elements on the sides.

At the moment I meshed the solid with constant sizes of the mesh (with edge dimensions of 25, 10, 7, 5), using Rsurf for the surfaces and Advancing front for the volumes. However, I am not able to create a graded mesh: the programs compute the mesh but some elements appear with zero volume.

With reference to the attached image, let's say that I wanted to divide the red volume in a grid of 3 x 60 x 20, then the two green's with elements of variable volume to make the transition to the blue ones, which have big elements.

Using GiD 13 (last version), there is no hint of zero volume elements, but during calculation they are encountered. With Gid 11.0.8 it says that, close to the location of the acute corners between green and red, it cannot mesh and to enforce surface meshing (?).

Is it a mesher problem or something else? how can it be resolved? The geometry/Gid files are in the attachment.

Thank you!

your geometry has all entities duplicated!!!
e.g. the red layer has 2 overlapped volumes, not 1 (and also repeated surfaces, lines and points)

probably this is not what you want.
You can automatically delete all duplications with
Geometry->Edit->Collapse->Model

About the mesh sizes, if do you want to divide the red volume in a grid of 3 x 60 x 20 then you can assign to it a structured mesh (because in this case is a 6-sided volume)
Mesh->Structured->Volumes->Assign number of cells
select the volume
and then the amount of divisions on each three directions (selecting some line of each direction)

for the rest of the model you could left only the general mesh size and the general size transition parameter , like this image: If do you want more control of the mesh sizes could assign unstructured mesh sizes to the rest of geometrical entities you want, specially to lines.
I attach again your model