ESM4714
Scientific Visual Data Analysis and Multimedia

Assignment #4:
Topological Structures in a Fluid Mixing Layer

Due: One week from the day it was assigned

Part I (90pts):
Calculate and Visualize a 3D Scalar Velocity Field

Given:
Three components u, v, w of the velocity vector field in three dimensional space: FILES: u61.bin, v61.bin, and w61.bin in directory /optical/ESM4714/examples/ragab/original_data. For more information on the mixing layer simulation you can link to Sources of Scientific Data Sets,see Fig. 3, or select normalized and scaled if you are just interested in how the data was processed into a binary format.

Determine:
The magnitude (scalar) of the velocity field in three dimensional space. Create a SDS_HDF file and call it your-last-name .vel61.hdf. What is the Maximum and Minimum velocities (give answer in normalized units)? Hint: the ASCII file for the scalar velocity field should not have to be scaled to the range 0 to 255. Does the maximum and minimum values occurr in more than one location? Is there a physical explanation for your observations? Create a text file your-last-name .txt which contains your answers and comments relevant to this assignment. Because HDF files are platform independent you can use several different software tools to view your HDF file:

• Java Slicer applet can be downloaded from the Download Instruction web site. You can down load this java applet on your computer but you need to install Java runtime environment, or you cand download the slicer applet in your home directory on the constellation.smvc.vt.edu Linux computers in the lab. You will need to add a new line, export CLASSPATH=. , to your .bash_profile file in your home directory for java to work. To start up the the Slicer.class applet go into the directory where Slicer.class is located and at the bash shell prompt type $ java Slicer, and the Java applet should appear. Select Open URL and a new window should appear prompting Enter an URL: _______________. In the space provided enter the path to your HDF file, e.g. ../hdf_files/lastname.vel61.hdf and an image should appear in the viewing window.

• If you are on the planet.smvc.vt.edu computers you can use xds. You can get a copy of xds from the rkriz home-directory/bin directory: % cp ../~rkriz/bin . NOTE: that final period copies the xds file to your current directory. You can learn how to use xds in Exercise-5

• You can also view your HDF file in PV-Wave, however I have yet to construct a Web exercise showing how to view HDF files in PV-Wave. Extra credit if you figure this out and make html summary of the procedure --- 8^)

• You can also transfer your HDF file to the two G3 Mac computers and use Spyglass Dicer, see Exercise-6.

Here are two fortran programs to help you get started. I will also pass out similar C programs in class that accomplish the same task:

Fortran program calculates velocity vector (incomplete): vel_scale_mag.f

Fortran program creates HDF file (complete): m_sds_vel61_hdf.f

NOTE: Compile with links to HDF libraries as described in Exercise 3:

% f77 m_sds_vel61_hdf.f -o m_sds_vel61_hdf.x -L/apps/hdf/lib -ldf -lz (on Sparc20s)

Comment:
This data set was generated by Dr. Saad Ragab of the Department of Engineering Science and Mechanics. Mr. Dan Mullholand, a student in the Spring class of 1993, work with Dr. Ragab and his graduate students on another data set similar to this one for his class project. You can review his mosaic summary and/or you can review a copy of his multimedia class project on request (Dan's class project was too large to included it on the Mac side of your optical disk as an example). Dan made a brief Mosaic summary of this project at 1993 Class Projects . Dan now has his own Mosaic Home Page at the University of Indiana.

Part II (10 pts):
Post your results on the homework account

Put a copy of any C and FORTRAN programs you used in this assignment and your lastname .vel61.hdf, in your lastname directory. Also put a copy of a text file lastname.txt with your comments on homework assignment#4. Print a copy of your files and also hand these copies in at class on the due date.

Your grade will be based on your observations conclusions and how well your file works. Your grade will not be based on your programming skills although brevity, clarity, and meaningful comment statements will be appreciated.