unstructured mesh of a parallelepiped

Synopsis

mkgeo_ugrid [options] n

Example

    mkgeo_ugrid -t 10 > square-10.geo
    geo square-10.geo

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

Description

This command is useful when testing programs on simple geometries. Invocation is similar to those of mkgeo_grid . It callsg 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, tetrahedra, prisms and hexahedra. It supports also mixed 2D with triangles and quadrangles:

    mkgeo_ugrid -tq 10 | geo -

and mixed 3D with tetraedra, prisms and/or hexahedra:

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

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.

-tq

‍ 2d mesh using both triangles and quadrangles.

-TP
-PH
-TPH

‍ 3d mixed mesh combining tetrahedra, prisms and/or 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.

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.

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 ).

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.

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.

The mesh order

This option is related to curved boundaries. Since boundaries are here flat, this option has no practical effect and is provided for test purpose only.

-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. Default is order=1.

Implementation

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