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** COPYRIGHT (C) 1996-2012, XYZ Scientific Applications, Inc. **
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** These coded instructions, statements, and computer programs contain **
** unpublished proprietary information of XYZ Scientific Applications, **
** Inc., and are protected by Federal copyright law. They may not be **
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ABOUT THIS TEMPLATE
INPUT FILE: input
TEMPLATE FILE TO EDIT: template
The geometry for the nacelle under consideration is assumed to
be oriented in a standard way, and all surfaces for the spinner
grouped into 1 TrueGrid composite surface. Similarly, all
surfaces for the nacelle should be grouped into 1 TrueGrid
composite surface.
After the geometry is oriented and grouped, a few parameters
must be set to reflect gross bounds and element sizes for the
mesh. Everything else is automatic. It will take some time
for the problem to run because of elliptic smoothing commands.
(It takes about an hour on an HP 9000/712.)
1. ORIENT THE GEOMETRY
(*) Import the IGES file for this problem using
iges IGES-file-name 1 1;
where IGES-file-name is the name of your IGES file.
(*) Use the Environment Window labels options to label points
on surfaces. Zoom way in on the tip of the spinner, and select
the point at the tip. Save the coordinates by typing a 'C'
in the text window, followed by a space. Then press F9 to
print the coordinates of the labeled point, and hit RETURN.
C 1.4171407e+02 8.4668256e-02 -2.6270186e-10
Change the parameters 'xcenter', 'ycenter', 'zcenter' to the
coordinates of this point (lines 30-32 of the template file).
line 29: para
xcenter 1.4171407e+02
ycenter 8.4668256e-02
zcenter -2.6270186e-10
;
(*) Determine a rotational transformation to position the
geometry so that
(i) The positive z-axis coincides with the axis of the
spinner, and points in the same direction as the spinner;
(ii) All cylindrical angles of the geometry are between
0 and 180 degrees.
Replace the transformation on line 36 of the input file with
your transformation.
line 36: ry 90
Be sure to change the name of the IGES file.
line 34: iges /users/d/BOEING1/nnacell.igs 1 1
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2. GROUP THE GEOMETRY
Label the surfaces using an appropriate labels option in the
Environment window.
Replace the numerical range 1:14 on line 41 with the surface
numbers of all surfaces of the nacelle (outer ring)
line 41: sd 101 sds 1:14;
Replace the numerical range 15:17 on line 45 with the surface
numbers of all surfaces of the spinner.
line 45: sd 102 sds 15:17
3. ESTABLISH GLOBAL BOUNDS
Specify a maximum z-coordinate for the problem. This z-coordinate
should be at least 20 units larger than the largest z-coordinate of
any point of the geometry (30 or 40 is better)
line 49: zmax 100
Specify a minimum z-coordinate for the problem. A z-plane at the
chosen value must NOT be below any part of the lower edges of the
nacelle or spinner surfaces.
line 50: zmin -80
Specify a maximum radius. This radius must be at least 20 units
larger than the largest radius of any point on the geometry (30
or 40 is better)
line 51: rmax 120
4. SPECIFY ELEMENT SIZES, DENSITIES
Boundary layers are automatically constructed as "offsets" of the
original geometry. These layers are chosen to be about 10-12 units
thick. These boundary layers are fixed, except that the number of
elements in them, as well as the size of the first layer, can be
specified.
NUMBER OF ELEMENTS IN BOUNDARY LAYER AROUND THE NACELLE
line 53: naclayer 30
THICKNESS OF THE FIRST LAYER AROUND THE NACELLE
line 54: naclsiz .0001
NUMBER OF ELEMENTS IN BOUNDARY LAYER AROUND THE SPINNER
line 55: spinlayer 18
THICKNESS OF THE FIRST LAYER AROUND THE SPINNER
line 56: spinlsiz .001
The element size in unzoned regions determines all other densities:
APPROXIMATE SIZE OF ELEMENTS IN UNZONED REGIONS
line 58: elemsize 3.5
Element densities everywhere are adjusted so that elements in unzoned
regions will be *about* elemsize by elemsize units.
5. RUN THE MODIFIED TEMPLATE
tg i=input len=40
After the geometry is imported and additional curves are constructed
the program will begin an interactive session. Make sure everything
looks okay at this point.
The block structure for the cylindrical mesh is as shown
r = 0
_______________________________ z = zmax
| | | | |
| | | | |
| | | | |
|___|________|___________|______|
| | |\ /| |
| | | \ _____ / | |
| | | | | | |
| | | | | | |
|___|________|__| | | |
\ \ | | | | |
| | | | | | |
Z | | | | | | |
/ \ | | | | | | |
| | | | | | | |
| | | | | | | |
| \ | | | | | | |
----- R |___|_______|__|_____|__|______| z = zmin
/
| | | | r = rmax
| | > | | <
| | 'naclayer' number of elements
| | 'naclsiz' is the size of the first layer
| |
> | | <
'spinlayer' number of elements
'spinlsiz' is the size of the first layer
User Specified Parameters
zmax : maximum z-coordinate of mesh
zmin : minimum z-coordinate of mesh
rmax : maximum r-coordinate of mesh
naclayer : number of elements near the nacelle
naclsiz : size of the first layer near the nacelle
spinlayer : number of elements near the spinner
spinlsiz : size of the first layer near the spinner
elemsize : rough size of elements in unzoned regions
Home PageQuestions, comments, suggestions
Copyright © 1996-2011 XYZ Scientific Applications, Inc. All rights reserved.
www.truegrid.com/nac1.html Jan. 3, 2011