You can specify some elements to be fixed, and others to be floatable.
A fixed tria-quad element is one that must be exactly represented as a face of a
tetra/penta-pyramid/hexa element in the final mesh. A floatable element is one whose
nodes locations are used, but the exact connectivity of those nodes can be modified
if it produces a better mesh. Unless you need a special mesh type, such as surface
layers of pentas/hexas, you should select as fixed only those elements that must
match a pre-existing mesh, leaving the rest floatable. If the bounding surface
contains quad elements, and if these quad elements are defined as fixedelements,
then a first layer of elements is generated on the boundary, and pyramid elements
are generated from the quad faces. However, when quad elements are defined as float
elements, they are split into two trias, and the tetra meshing proceeds
normally.
You can also specify various growth options in order to control the tradeoff between
the number of tetras generated and their quality. Higher, more aggressive growth
rates produce fewer elements, but they may be of poorer quality.
In the Tetramesh panel you can choose from three different mesh generation
priorities. The generate mesh normally option applies in most
cases, but if your solver is particularly sensitive to element quality, use the
optimize element quality option. This directs the
tetramesher to spend more time trying to generate better quality elements. In
particular, it employs the volumetric ratio (CFD "skew") measurement for rating
potential tetras. For some applications, element quality considerations are less
important than mesh generation time. In those cases, choose the optimize
meshing speed option.
From the 3D page, click Tetramesh.
Access different types of tetra meshing from the subpanels.
Subpanel
Description
Tetra mesh
Fills an arbitrary volume, defined by its surface
using tria/quad elements, with tetrahedral
elements.
Tetra remesh
Regenerates the mesh for a single volume of
tetrahedral elements.
Volume tetra
Given a solid entity or a set of surfaces
representing a closed volume, this meshing option
generates a shell mesh and fills the enclosed volume
with solid elements. You can choose to create a shell
mesh (2D) using quads, trias, or mixed elements and a
solid mesh (3D) using tetrahedral elements only or mixed
(tetras and penta) elements. In addition, you can use
proximity meshing, which refines the mesh in areas where
the features are small and closer together. Figure 1.
You can also use surface curvature as a function
of element density as shown below. This option creates
finer mesh in areas of high surface curvature. Figure 2.
When you select quads or mixed as your 2D element
type, HyperMesh creates quad
elements and splits them diagonally into two trias
during tetra face creation. This can create tetra
elements whose triangular faces are right triangles
(90-45-45 angles) instead of equilateral triangles
(60-60-60 angles). Figure 3.
Note: Sometimes the meshing may fail to correctly
interpolate from the surface mesh; when this occurs,
the shell elements are cleaned up according to the
same settings used in the Quick TetraMesh macro on
the Utility menu, and a
second attempt is made. This means that some of the
features in a model may be smoothed
over.
Tetramesh parameters
Sets general qualities of the tetrameshing engine,
such as a maximum element size, growth rate, the balance
between speed and element quality, or whether to perform
smoothing operations after initial meshing.
Refinement box
Lets you define a specific box-shaped volume within
an existing teramesh in which to generate finer
mesh.
