## SYNOPSIS

mkgeo_ugrid *options* [*n*]

## EXAMPLE

The following command build a triangle based 2d unstructured mesh of the unit square:

mkgeo_ugrid -t 10 > square-10.geo geo -mayavi square-10.geoor in one comand line:

mkgeo_ugrid -t 10 | geo -mayavi -

## DESCRIPTION

This command is usefull when testing programs on simple geometries.
Invocation is similar to **mkgeo_grid** (see mkgeo_grid(1)).
It calls **gmsh** as unstructured mesh generator.
It avoid the preparation of an input file for a mesh generator.
The optional *n* argument is an integer
that specifies the subdivision in each direction. By default
*n*=10.
The mesh files goes on standard output.

The command supports all the possible element types: edges, triangles, rectangles, tetraedra, prisms and hexahedra. It supports also mixed 2D with triangles and quadrangles:

mkgeo_ugrid -tq 10 | geo -mayavi -and mixed 3D with tetraedra, prisms and/or hjexaedra:

mkgeo_ugrid -TP 10 | geo -mayavi - mkgeo_ugrid -PH 10 | geo -mayavi - mkgeo_ugrid -TPH 10 | geo -mayavi -

## ELEMENT TYPE OPTIONS

**-e**- 1d mesh using edges.
**-t**- 2d mesh using triangles.
**-q**- 2d mesh using quadrangles.
**-tq**- 2d mesh using both triangles and quadrangles.
**-T**- 3d mesh using tetraedra.
**-P**- 3d mesh using prisms.
**-H**- 3d mesh using hexahedra.
**-TP****-PH****-TPH**- 3d mesh using a mixt between tetraedra, prisms and/or hexahedra.

## THE GEOMETRY

The geometry can be any [a,b] segment, [a,b]x[c,d] rectangle or [a,b]x[c,d]x[f,g] parallelotope. By default a=c=f=0 and b=d=g=1, thus, the unit boxes are considered. For instance, the following command meshes the [-2,2]x[-1.5, 1.5] rectangle:

mkgeo_ugrid -t 10 -a -2 -b 2 -c -1.5 -d 1.5 | geo -

**-a***float***-b***float***-c***float***-d***float***-f***float***-g***float*

## BOUNDARY DOMAINS

**-sides****-nosides**-
The boundary sides are representd by domains:
**left**,**right**,**top**,**bottom**,**front**and**back**. **-boundary****-noboundary**-
This option defines a domain named
**boundary**that groups all sides. By default, both sides and the whole boundary are defined as domains:mkgeo_ugrid -t 10 > square.geo geo square.geo mkgeo_ugrid -t 10 -nosides > square.geo geo square.geo mkgeo_ugrid -t 10 -noboundary > square.geo geo square.geo mkgeo_ugrid -t 10 -noboundary -nosides > square.geo geo square.geo

## REGIONS

**-region****-noregion**-
The whole domain is splitted into two subdomains:
**east**and**west**, This option is used for testing computations with subdomains (e.g. transmission problem; see the user manual).mkgeo_ugrid -t 10 -region | geo -

## CORNERS

**-corner****-nocorner**-
The corners (four in 2D and eight in 3D) are defined as OD-domains.
This could be usefull for some special boundary conditions.
mkgeo_ugrid -t 10 -corner | geo - mkgeo_ugrid -T 5 -corner | geo -

## THE MESH ORDER

**-order int**-
The polynomial approximation mesh order, as defined by
**gmsh**. This option enable a possible curved boundary, when applying a suitable nonlinear transformation to the mesh. Defualt is order=1.

## OTHERS OPTIONS

**-clean**- clear temporary files (this is the default).
**-noclean**- does not clear temporary files.