structured mesh of a parallelepiped

Synopsis

mkgeo_grid [options] [nx [ny [nz]]]

Examples

The following command build a triangular based 2d 10x10 grid of the unit square:

    mkgeo_grid -t 10 > square-10.geo
    geo square-10.geo

or in one command line:

    mkgeo_grid -t 10 | geo -

Description

This command is useful when testing programs on simple geometries. It avoid the preparation of an input file for a mesh generator. The optional nx, ny and nz arguments are integer that specifies the subdivision in each direction. By default nx=10, ny=nx and nz=ny. The mesh files goes on standard output.

The command supports all the possible element types: edges, triangles, rectangles, tetrahedra, prisms and hexahedra.

Element type option

-e

1d mesh using edges. -t 2d mesh using triangles. -q 2d mesh using quadrangles (rectangles). -T 3d mesh using tetrahedra. -P 3d mesh using prisms. -H 3d mesh using hexahedra.

The geometry

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

The geometry can be any [a,b] segment, [a,b]x[c,d] rectangle or [a,b]x[c,d]x[f,g] parallelepiped. 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_grid -t 10 -a -2 -b 2 -c -1.5 -d 1.5 | geo -

Boundary domains

-[no]sides

The boundary sides are represented by domains: left, right, top, bottom, front and back. -[no]boundary This option defines a domain named boundary that groups all sides.

By default, both sides and the whole boundary are defined as domains:

    mkgeo_grid -t 10 -nosides | geo -
    mkgeo_grid -t 10 -noboundary | geo -
    mkgeo_grid -t 10 -noboundary -nosides | geo -

Regions

-[no]region

The whole domain is split into two subdomains: east and west. Also, the separating domain is named interface in the mesh. This option is used for testing computations with subdomains (e.g. transmission problem; see User's guide ).

Example:

    mkgeo_grid -t 10 -region | geo -

Corners

-[no]corner

The corners (four in 2D and eight in 3D) are defined as OD-domains. This could be useful for some special boundary conditions.

Example:

    mkgeo_grid -t 10 -corner | geo -
    mkgeo_grid -T  5 -corner | geo -

Coordinate system options

-cartesian
-rz
-zr

Specifies the coordinate system. The default is cartesian while -rz and -zr denotes some axisymmetric coordinate systems. Recall that most of Rheolef codes are coordinate-system independent and the coordinate system is specified in the geometry file .geo.

Implementation

This documentation has been generated from file main/sbin/mkgeo_grid.sh