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.TH mkgeo_contraction 1rheolef "rheolef-7.0" "rheolef-7.0" "rheolef-7.0"
.\" label: Prog:mkgeo_contraction
.SH NAME
\fBmkgeo_contraction\fP -- build an unstructured 2d mesh of an abrupt contraction
.\" skip: @pindex mkgeo_contraction
.\" skip: @pindex geo
.\" skip: @cindex mesh
.\" skip: @fiindex @file{.geo} mesh
.SH SYNOPSIS

.\" begin_example
.Sp
.nf
  mkgeo_contraction \fIoptions\fP [\fInx\fP [\fIny\fP [\fInz\fP]]]
.Sp
.fi
.\" end_example
.\" skip: @pindex mkgeo_contraction
.\" skip: @pindex geo
.\" skip: @cindex mesh
.\" skip: @fiindex @file{.geo} mesh
.SH EXAMPLE

The following command build a triangle-based 2d unstructured mesh
of the [-10,0]x[0,4] u [0,10]x[0,1] mesh
.\" begin_example
.Sp
.nf
        mkgeo_contraction > contraction.geo
        geo contraction.geo
.Sp
.fi
.\" end_example
.SH DESCRIPTION

.\" skip: @pindex bamg
This command is convenient for building a mesh for
the abrupt contraction, as it is a very classical benchmark in complex
fluid flow problems.
It calls \fBbamg\fP unstructured mesh generator
with anisotropy feature.
The mesh files goes on `\fB@var{name'\fP.geo} where \fIname\fP
is the basename for the output (see option \fB-name\fP below).
The three auxiliary files required for automatic mesh generation
with Rheolef combined with \fBbamg\fP are also provided:
`\fB@var{name'\fP\fB.bamg\fP},
`\fB@var{name'\fP\fB.bamgcad\fP} and
`\fB@var{name'\fP\fB.dmn\fP}.
.SH THE GEOMETRY

The geometry is [-Lu,0]x[0,d] u [0,Ld]x[0,1].
By default c=4 is the contraction ratio and Lu=Ld=10
are the upstream and downstream pipe lengths.
.\" begin table
.\" start item
.TP
.B -c \fIfloat\fP
.\" start item
.TP
.B -Lu \fIfloat\fP
.\" start item
.TP
.B -Ld \fIfloat\fP
These options control the geometry parameters.
.\" start item
.TP
.B -cartesian
.\" start item
.TP
.B -zr
.\" start item
.TP
.B -rz
These options control the geometry coordinate system.
Default is cartesian.
THE DISCRETIZATION:
The optional \fInx\fP and \fIny\fP arguments are floats
that specifies the subdivision in each direction.
By default \fInx\fP=1 and \fIny\fP=\fIny\fP.
Changing the density applies the factor 1/\fIn\fP to all the mesh edges lengths.
.\" start item
.TP
.B -hmin \fIfloat\fP
Controls the edge length at the re-entrant corner of the contraction.
Default is \fBhmin\fP=0.1.
Changing the density by the previous options
applies the factor 1/\fIn\fP to \fBhmin\fP also.
.\" end table
.SH BOUNDARY DOMAINS

The boundary sides are represented by domains: \fBaxis\fP, \fBwall\fP,
\fBupstream\fP and \fBdownstream\fP.
.SH OTHERS OPTIONS

.\" begin table
.\" start item
.TP
.B -name \fIstring\fP
Set the basename for the output files.
By default, the basename is \fBcontraction\fP.
.\" start item
.TP
.B -split
.\" start item
.TP
.B -nosplit
Split each triangle in three substriangles by inserting the barycenter as
an additional node. This is useful for using the Scott and Vogelius
incompressible mixed finite element P2-P1d for velocity-pressure approximation.
Default is no split.
.\" start item
.TP
.B -clean
.\" start item
.TP
.B -noclean
Clear temporary files (this is the default).
.\" start item
.TP
.B -verbose
.\" start item
.TP
.B -noverbose
In verbose mode, print to stderr all subcommands and logs.
.\" end table
.\" END
.SH COPYRIGHT
Copyright (C) 2000-2018 Pierre Saramito <Pierre.Saramito@imag.fr> GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.  There is NO WARRANTY, to the extent permitted by law.