Introduction
In V2006, the Residual Plotter in CFD-FASTRAN-GUI has
been improved to plot all of the output files that
CFD-FASTRAN creates. In addition to the global
residual history (RSL), CFD-FASTRAN may produce
output files with the extensions *.RZ, *.FORCE,
*.VFORCE, *.AFS, *.DYNA, *.DYNB, *.KINA, *.KINB,
depending on the problem.
To plot any of these output files, launch the
"Residual Plotter" from the Run panel as usual, then
use the File→Open panel to
load the file you want. You can open many files and
easily switch between them using the Recently Opened
Files list -- or -- you can open more than one
residual plotter at a time.
The rest of this tip describes the meaning of the
output files that CFD-FASTRAN creates, plus the
format of the self-describing header that allows them
all to be handled in the same way by the residual
plotter.
The 2006 residual plotter also introduced more and
better control over plotter ranges, grid lines, tick
fonts and attribute. Coming in 2007, the plotter will
introduce a stand alone capability so that users can
monitor convergence without having to launch the GUI
and load the DTF file.
CFD-FASTRAN Output File Descriptions
In addition to the global residual history (RSL), the
improved residual plotter can now plot ASCII files
output by the solver, with extensions *.RZ, *.FORCE,
*.VFORCE, *.AFS, *.DYNA, *.DYNB, *.KINA, *.KINB.
The description of the each of these files is as
follows:
RSL: The model.RSL file is used by
CFD-FASTRAN-GUI to plot the maximum residual of the
entire domain for density, u velocity, v velocity, w
velocity, pressure and other variables.
RZ:The model.RZ file contains residuals for
each variable in a particular zone. The ability to
visualize the RZ file should be helpful in
identifying troublesome zones in simulations that are
not converging well.
FORCE & VFORCE: The model.FORCE and
model.VFORCE files contain the total aerodynamic and
shear (viscous) forces, respectively. The total force
and moments are given in x, y, and z components in an
inertial frame of reference. Note that the moments
are calculated about the point (0, 0, 0). The area,
A, does not reflect the surface area of blocked
regions. The units are N and N-m for forces and
moments. For a steady state simulation the viscous
force and shear force history can be plotted to
monitor the convergence. At convergence the force
values should not change and should become flat.
DYNA & DYNB: The model.DYNA* and model.DYNB*
files contain force and moment data created by each
motion model. "DYN" is shorthand for dynamics. At
each cycle, model.DYNA* contains the individual
forces in the x, y, and z directions. The individual
forces printed in the file depend on the options
selected in CFD-FASTRAN-GUI. For example, forces due
to aerodynamic, gravity, and point forces are listed
separately. The model.DYNB* file lists the total
forces in the x, y, and z directions for both
inertial and body fixed axes. The total moments taken
about the inertial (0, 0, 0) are also listed in
inertial and body fixed axes.
KINA & KINB: The files model.KINA* and
model.KINB* contain motion-related information for
each motion model. "KIN" is shorthand for kinematics.
Again, each motion model creates a unique kinematic
file. In model.KINA*, the position, linear velocity
and linear acceleration of the center of gravity of a
motion model are printed out for each cycle.
In model.KINB*, the following four quantities are
printed out for a motion model:
-
Inertial Displacement (deg): This is angular
displacement of the body in the inertial frame.
-
Body-Fixed Displacement (deg): This is sum of the
small angular displacements at each time step in
the instantaneous body-fixed axis system.
-
Body-Fixed Velocity (deg/s): This is angular
velocity in the instantaneous body fixed axis
system.
-
Body-Fixed Acceleration (deg/s2): This is angular
acceleration in the instantaneous body-fixed axis
system.
AFS & FOR: The model.ASF* and model.FOR.* file
contains the aerodynamic forces (coefficients) and
moments (coefficients) at every cycle according to
the configuration options set by the user in
Aerodynamic Force Summary and Aero Force Section
Summary, respectively, in CFD-FASTRAN-GUI. The *
indicates the number of the output file in case the
user has defined multiple outputs.
Format of Self-Describing Header
The header format of all the files is same which
allows the user to plot the files in the same
residual plotter (example
residual file, example
aerodynamic force summary ).
Figure 1. CFD-FASTRAN-GUI residual plotter.
The header of each file has 4 lines as shown
here.
Plot Title: This line gives the title to the
plot.
Xcolumn(s): The value of Xcolumn is set to
either 0 or 1 depending on the file type. For RSL,
RZ, FORCE and VFORCE files the quantities are plotted
with respect to number of iterations and the value
for Xcolumn is set to 0. For transient simulations,
for which DYNA, DYNB, KINA and KINB files are also
output, the quantities are plotted with respect to
time. In that case the value of Xcolumn is set to 1.
IgnoreColumn(s): This value defines the Column
numbers, which are not used for plotting. For
example, in case of 2D simulations, the column for
RHO_W variable residual is ignored because it is not
solved. In case of DYNA file, if the user has not
defined the thrust model, then the column outputting
the thrust forces are ignored for plotting purpose.
Label(s): The last line defines the name of
the variables for which the residuals, forces or
other quantities are being plotted.
If you have any questions about this feature or would
like us to discuss some other topic in the future,
please let us know.
Regards,
Amit Saxena
Senior Applications Engineer
|
