Case Studies
West Lafayette, IN - March 2001
2-D Slice Along the Axis of a 3-D Simulation of Fully-turbulent
Jet Flow
View
AVI movie (11.3 MB)
David Glase, a graduate student pursuing a Ph.D. in Mechanical
Engineering at Purdue University, makes extensive use of Tecplot for generating
figures for technical publications. He also uses Tecplot's 2D and 3D visualisation
features to gain a better physical understanding of his simulation results.
David has tried other visualisation packages, but found them quite limiting
when compared to Tecplot. "In Tecplot, I can do almost anything I can
dream up... The use of macros, layouts, style sheets, and binary data
files from my own post-processing code has saved me quite a bit of time."
David's research group, directed by Dr. Steven H. Frankel, focuses on
fundamental research and numerical modeling of turbulence in a variety
of disciplines, including combustion, aeroacoustics, and multiphase flows.
David is currently working toward developing subgrid-scale combustion
models for turbulent flames using the Large Eddy Simulation (LES) technique.
The Image of the Month is from a small portion of a nonreacting simulation,
which was used to validate the numerical method and the inlet and boundary
conditions before progressing to a reacting flow. The animation is a two-dimensional
slice along the axis of a three-dimensional simulation of fully-turbulent
jet flow exiting into a slower-moving co-flow in a square duct. The grayscale
contours represent mixture fraction, which can be used to identify the
composition of the mixture. This can be thought of as a smoke tracer added
to the jet flow. The lower half of the plot shows velocity vectors, colored
and scaled by their relative magnitude. The duration of the movie represents
about 70ms of time in a 26mm gas jet operating at a Reynolds number of
21,000.
The simulation was run on the NCSA SGI Origin2000 Supercomputer. The code
runs in parallel on 16 processors, using a total of about 6 GB of RAM
and about 10,000 hours of CPU time. The data was written to disk using
the HDF file format. After the simulation was complete, a post-processing
code read in the HDF files and wrote the appropriate Tecplot-formatted
binary data files (using the Tecplot-supplied libraries).
The plots consist of two separate frames, each linked to a different data
file. The frame containing the velocity vectors is on top, and has a transparent
background. Value blanking is used along the centerline of the figure.
The mixture fraction contours are made with a standard flooded contour
plot.
Tips: David wanted to use two different colormaps
for the two different data types, but only one colormap is allowed at
a time in Tecplot. He fixed this by shifting the mixture fraction data
in the contour plot so that its entire range of values lie below the range
of values for the vector plot. He then built a custom colormap, with the
lower half being grayscale and the upper half being the standard rainbow.
He then plotted both data sets on the same colormap.
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