Auto Trex Tutorial 3t3i3e

AUTOMATIC
T‐REX
MESH
TUTORIAL
 The
steps
outlined
in
this
tutorial
describe
the
procedure
used
to
automatically
create
an
unstructured
 block
that
contains
anisotropic
tetrahedra.
Currently,
the
anisotropic
mesher
T‐Rex
is
only
available
in
 Gridgen.
However,
using
the
auto‐trex.glf
script,
Pointwise
can
be
used
up
to
the
point
of
block
 initialization.

 
 • Open
pipe.pw
in
Pointwise
(see
following
image)
 
 Notice
that
this
file
contains
both
database
and
grid
elements.
Therefore,
when
exporting,
Pointwise
 should
export
both
a
.dba
and
.gg
file.
Also
note
that
a
block
has
already
been
created
but
not
initialized,
 that
will
be
left
up
to
the
script
to
take
care
of
automatically.

 



 
 The
next
step
is
to
color
the
domains
appropriately
depending
on
whether
they
are
either
symmetry
or
 no‐extrusion
domains.
Symmetry
domains
must
be
colored
red
(RGB
255,0,0)
and
no‐extrusion
domains
 must
be
colored
blue
(RGB
0,0,255).
All
other
domains
are
considered
extrusion
domains
and
must
not
 be
red
or
blue.

 
 • Turn
on
the
Domains
Mask





•

Select
the
Symmetry
domains,
dom‐5
and
dom‐6


•

Go
to
the
Attributes

and
change
the
color
of
the
two
domains
to
red
(RGB
255,0,0)


•

Now
select
the
No‐Extrusion
domains,
dom‐1,
dom‐2,
dom‐3,
and
dom‐4


•

Go
to
the
Attributes

and
change
the
color
of
the
four
domans
to
blue
(RGB
0,0,255)



Now
all
the
domains
have
been
specified
as
either
symmetry,
no‐extrusion,
or
extrusion
domains
and
the
 project
is
ready
to
be
exported
to
Gridgen
(see
following
figure).

 



 The
last
step
before
preparing
the
params.dat
file
is
to
export
the
.dba
and
.gg
files.
 
 • Click
Export
to
Gridgen
in
the
File
menu
to
export
the
.dba
and
.gg
files After
the
files
have
been
exported,
they
need
to
be
placed
in
the
directory
containing
the
auto‐trex.glf
and
 params.dat
files
(see
following
figure).
 



 The
next
step
is
to
input
the
required
information
into
the
params.dat
file.
The
params.dat
file
contains
 file
information,
boundary
layer
parameters,
several
advanced
solver
settings,
and
mesh
checking
 parameters.
All
of
this
information
is
read
and
checked
by
auto‐trex.glf
upon
execution.

 
 • Open
params.dat
and
fill
it
out
with
the
correct
file
information.
The
other
parameters
can
be
left
 at
their
default
value
for
this
tutorial,
but
take
some
time
to
look
at
all
the
parameters
available
in
 the
input
file
(see
following
figure).
 • Save
params.dat

Once
the
input
file
has
been
filled
out
correctly
and
all
the
files
are
in
the
same
directory,
the
auto‐trex.glf
 script
can
be
executed.
To
do
this,
Gridgen
needs
to
be
executed
in
batch
mode
while
reading
the
glyph
 script.
For
more
information
on
executing
Gridgen
in
batch
mode,
see
the
REE.txt
document.

 
 • Execute
Gridgen
and
auto‐trex.glf
in
batch
mode
(e.g.
gridgen
–b
auto‐trex.glf) As
the
script
is
running,
some
information
should
be
printing
out
in
the
command
window
letting
the
 
know
the
progress
of
the
operation.
When
the
script
has
finished
running,
the
command
window
 should
have
some
diagnostics
information
presented
in
three
tables
(see
following
figure).

 



 
 Also,
a
new
file
should
be
present
in
the
directory
containing
the
params.dat,
auto‐trex.glf,
and
the
.dba
 and
.gg
files.
The
name
of
the
new
grid
file
should
be
the
same
as
the
original
grid
file
name
appeneded
 with
“‐ANISO”
(see
following
figure).
 



 
 
 Now
the
final
anisotropic
block
can
be
examined
in
Pointwise
(see
following
figures).

 
 • Import
the
original
.dba
file



 
 


•

Import
the
–ANISO.gg
file


•

Select
the
block
and
go
to
Examine‐>Volume


•

Click
the
Cuts
tab
and
check
Enable
Cutting
and
choose
the
Z‐direction


•

Disable
Domains
for
a
better
view
of
the
cut