# AcuMesh2Tet

Convert a mesh into an all-tetrahedra mesh.

## Syntax

acuMesh2Tet [options]

## Type

AcuSolve Preparatory Program

## Description

Since tetrahedra are much more efficient in terms of CPU and memory usage than other element topologies, and have nearly the same accuracy, it is often very advantageous to convert pyramids, wedges, hexes, and high-order tetrahedra into linear (4-node) tetrahedra. AcuMesh2Tet is a simple utility program that does this conversion for both interior and surface elements.

For each interior connectivity file file, AcuMesh2Tet produces a tetrahedra file file.tet. Similarly, for each file srf_file in the surface file list, a triangle surface file srf_file.tri is produced.

It is important to specify any periodic boundary condition files in periodic_bc_file_list if they exist. They are used to ensure that the resulting mesh is continuous across periodic surfaces.

In the following, the full name of each option is followed by its abbreviated name and its type. For a general description of option specifications, see Command Line Options and Configuration Files. See below for more individual option details:

help or h (boolean)
If set, the program prints a usage message and exits. The usage message includes all available options, their current values, and the place where each option is set.
problem or pb (string)
The name of the problem is specified via this option. This name is used to generate input file names and extracted surface file names.
coordinates_file or crd (string)
Nodal coordinates file name. The file must contain four columns: node number and x, y, z coordinates. If coordinates_file is set to _auto, problem.crd and problem.crd.B are assumed.
connectivity_file_list or cnn (string)
Comma-separated list of connectivity files. The shape of the elements is extracted from the number of columns in each file. The elements are assumed to be 4-node tetrahedra if the file has 5 columns; 5-node pyramids if 6 columns; 6-node wedges if 7 columns; 8-node bricks if 9 columns; and 10-node tetrahedra if 11 columns. If connectivity_file_list is set to _auto, all problem*.cnn and problem*.cnn.B files are used.
periodic_bc_file_list or pbc (string)
Comma-separated list of periodic boundary condition files. If periodic_bc_file_list is set to _auto, all problem*.pbc and problem*.pbc.B files are used.
surface_file_list or srf (string)
Comma-separated list of surface files. The shape of the surfaces is extracted from the number of columns in each file. The surfaces are assumed to be 3-node triangles if the file has 5 columns; 4-node quads if 6 columns; and 6-node triangles if 8 columns. The surfaces in these files are removed from the generated surface files. If surface_file_list is set to _none, no surface file is read. If surface_file_list is set to _auto, then problem*.srf, problem*.srf.B, problem*.ebc, and problem*.ebc.B are used.
verbose or v (integer)
Set the verbose level for printing information to the screen. Each higher verbose level prints more information. If verbose is set to 0 (or less), only warning and error messages are printed. If verbose is set to 1, basic processing information is printed in addition to warning and error messages. This level is recommended. verbose levels greater than 1 provide information useful only for debugging.

## Examples

Consider the mesh of the channel problem. AcuSurf may be executed as:
acuMesh2Tet -pb channel -srf channel.outflow.srf,channel.wall.srf
or alternatively the options may be put into the configuration file Acusim.cnf as follows:
problem= channel
surface_file_list= channel.outflow.srf,channel.wall.srf
and AcuMesh2Tet invoked as
acuMesh2Tet

The result will be one new interior connectivity file and two new surface connectivity files: -channel.cnn.tet, channel.outflow.srf.tri and channel.wall.srf.tri.