SCENE August 1993



Table of Contents


The Nevada High School Supercomputing Initiative

by Sam West, Analyst in Charge

On June 7, 1993, the organizational meeting of the Nevada High School Supercomputing Initiative (NHSSI) was held. The NHSSI is a collaborative effort between the NSCEE and Nevada high schools that has as its mission "to make available the resources of the NSCEE to Nevada high school teachers and students with the intent of fostering interest in and competence with the tools, methods and purposes of supercomputing." In its first year, the pilot program for this Initiative is being established at the Clark County Magnet High School for Science and Technology.

Clark County School District personnel in attendance at that meeting included: Dr. Wayne Tanaka, Principal, Clark High; Jerry Morlan, Administrative specialist, Curriculum and Instruction; Joyce Woodhouse, School-Community Partnership Program; Debbi Crooks, Bill Crego and Kathy Clinesmith, CCSD Personnel.



Clark High School teachers visiting the supercomputer facilities

A follow-up meeting was held June 17, 1993 to discuss network issues and decide on an initial communication configuration. On June 21, Clark County School District personnel received NSCEE computer accounts and introductory training. Since then, additional NSCEE training sessions on UNIX, workstations and Internetworking have been held for the high school teachers.

Later in the summer we expect to spend more time with the CCSD teachers and students in anticipation of this coming school year.

Welcome, Clark High, we're glad to have you aboard.


New X Terminals in B361

by Ken Been, Graduate Research Assistant

The NSCEE has expanded its public facilities by installing 10 X Terminals in room B361 of the Thomas T. Beam engineering complex on the UNLV campus. Five 15" monochrome terminals and five 17" color terminals are available. They are located on the last two rows of tables in the lab.

The terminals are connected to the X display manager on the Convex C-220 (aurora). Users enter their login name and password to login to aurora. Aurora uses the Motif window manager. Users familiar with the window managers available on our Sun machines-OpenWindows and TWM-will see some minor differences in the look and feel of Motif.

The hours for the lab in B361 are:


NSCEE's New Staff Members

NSCEE is pleased to welcome Matthew Au and Rick Pinson to the staff.

Matthew Au

Matthew started July 1st as a software specialist for scientific data visualization and virtual reality. He received his B.S. and M.S. both in Computer Science from UNLV. During his last year as a graduate student, he worked at the Center as a research assistant developing a graphical user interface for engineering codes.


Rick Pinson

Rick Pinson joined NSCEE on May 1, 1993 as a supercomputer systems analyst and network specialist. Rick received a B.S. in Computer Science from Southern Oregon State in 1984. He then joined Productivity Products International and helped to develop Objective-C, an object oriented C compiler. He ported the compiler, actually a Pre-processor, to Unix based machines. Other projects included: a graphical interface to an SQL database, a human interface that allowed the Hartford Insurance Group to draw an insurance form and automatically generated the COBOL code, and a windowing system for Sun workstations that was later sold to NeXT which became the foundation for NeXTStep. Rick then joined the Science and Engineering Computing facility at Yale University. He was responsible for support of over 2,000 research personnel at Yale University and Yale Medical. He evaluated department needs, developed hardware, software, and network strategies and oversaw their implementation, and trained system support staff in Unix, VMS, MS-DOS, and MacOS. Next, Rick joined United Parcel Service Research and Development, where he developed computer and networking systems for automated facilities, helped to design the DIAD (the electronic clipboard), wrote the system supervisor code for a 17 axis robot, developed a stacking algorithm that averaged 72% space utilization, and has a patent pending on a new networking cable. Rick was also the chairman of the "Dream Team"; whose charter was to develop the 20 year technically for UPS. Rick then went to Caltech where he supervised the Molecular Modeling and Simulation Center Computing Facility. He designed the new facility and supervised construction. Rick has designed and built 9 computer facilities to date.


New Software Acquired

CONVEX

by Mike Ekadihl, Senior System Analyst

During June, the following convex applications were upgraded:

	CONVEX as, ld, libs V2.0.1
	CONVEX VECLIB V8.0
	CONVEX C V5.0
	CONVEX Fortran V8.0
	CXdb V2.0 

Release notes for each of these applications can be found by reading the appropriate files in /usr/doc on aurora.

In summary, several changes have been made to the optimization reporting from the C compiler. These improvements will provide better information to the applications programmer about vectorization.

Version 8.0 of the Fortran compiler has been extended to include masked array assignments and support for the Fortan 90 EOSHIFT and CSHIFT array intrinsics. Additionally, the optimization reporting has been enhanced.

Version 8.0 of the VECLIB library provides the functionality of "LAPACK" which was designed to supercede LINPACK and EISPACK. CONVEX LAPACK was derived from the public-domain version of LAPACK.

Linking Scientific Libraries

by Kan Bean, Graduate Research Assistant

The math libraries LINPACK, MINPACK, and level 3 BLAS have been installed on nye. Type "man linpack" to see how to link to the routines in them. (It's easy; just put "-llinpack" etc., on the f77 line.)

(GAMESS) General Atomic and Molecular Structure System

by Kan Bean, Graduate Research Assistant

The latest version of GAMESS, General Atomic and Molecular Structure System, has been installed on clark, nye, and aurora. GAMESS can perform a wide range of quantum chemical computations. Graphics routines, which can be easily used in conjunction with GAMESS, have also been installed (See figure below).These routines now provide the option of X window output for viewing on a workstation, or postscript output for making hardcopies.

		
	     Example output produced by GAMESS

More information can be found in the man page for GAMESS ("man gamess"). We also have documentation on-line in the directory /usr/public/gamess/man on nye and aurora, and in /usr/local/lib/gamess on clark. A hardcopy of this manual is in the NSCEE offices, where it can be read but not removed.


Research Reports

Numerical Simulation of the Turbulent Flow and Vaporizing Particle Dispersion in Three Dimension Round Jets

by Jeffrey Jay Lienau, Graduate Student, Mechanical Engineering Department, University of California, Davis

This research is an investigation of three dimensional round turbulent jets (7,500<Re<15,000) and the transport of particles released at the jet exit. The transport of particles in turbulent jets has environmental importance because it models the release of pollutants from stacks which is a very important phenomenon. It also has industrial applications in the area of spray combustors where liquid fuel droplets are released into turbulent gaseous jets and combustion occurs in the turbulent environment.

A large eddy simulation of the three dimensional turbulent jet for 60 diameters of the flow domain has been run at UNLV on the Cray Y-MP. A Fifth order accurate compact finite difference method has been used for solution of the unsteady three dimensional incompressible Navier Stokes equations in cylindrical coordinates [1]. The large eddy simulation model is the Smagorinsky Model [2]. The Poisson equation for pressure correction is solved using a compact finite difference-spectral hybrid method. A direct solver (LAPACK) is used for each spectral mode. Each spectral mode matrix is written to the SSD on the Cray Y-MP and is retrieved each time step using the buffer in/out commands. (Using the SSD on the Cray caused significant improvement in speed and I/O costs were decreased by about a factor of 10). The solution was transformed using a highly efficient real Fourier Transform (rfftmlt) and nearly all coding (including the tridiagonal matrices for the compact finite differences) is vectorized yielding an outstanding running speed of about 160 MFLOPS. The simulations, which contain roughly 200,000 grid points, run at about 2 cpu seconds per time step. A typical simulation will take roughly 10 SBU's. For additional information on the solution method see [3 and 4].

	

Figure 1 shows the contours of the cross flow velocity (in and out of the plane) for the 60 Diameter Large Eddy Simulation with C_s=.05. There is a rich variety of structures and scales of different sizes which develop roughly linearly in size with the downstream distance. A computation of the half width of the jet shows that the spreading of the jet is linear with about a 10% slope. This is in agreement with experimental observation. Also, the axial turbulence intensity normalized by the centerline velocity (Vz'/Vz) reaches a peak value of about 0.3 near the region where the largest radial gradient of Vz occurs. This is also in agreement with experimental observations.

     
			Figure 2

Figure 2 illustrates the initial development and breakdown of the jet. Regions of rings (donut shaped vortex at right) develop which contain an azimuthal instability which produces hairpin shaped vortices or lobes (left of figure). The ends of these hairpins get pulled in the flow direction by faster moving fluid near the centerline and produce streamwise braids or fingers of vorticity. The number of braids is in agreement with experimental results obtained by Liepmann. These fingers are actually pairs of counterrotating vortices which tend to increase entrainment and particle dispersion. For additional details see [5].

      
			   Figure 3

      
			   Figure 4

Figure 3 shows the particle dispersion for 113 microMeter pentane particles released into a 60 C heated jet. The Schmidt number was 1.5, the Reynolds Number was 15,000 and the Smagorinsky constant used was 0.05. It is seen that excellent agreement was obtained. Figure 4 shows the axial velocity autocorrelation for 50 microMeter HexaDecane particles released in a nonheated jet. These are integrated starting at 30 Diameters and the integral time scale (area under this curve) is calculated to be about 9 milliseconds at this axial distance. The experimental results were provided by Chuck Call [6].

In conclusion, fundamental research in turbulent jets with particle dispersion has been performed and experimental and computational results agreed well. This research was supported by the Air Force Office of Scientific Research (AFOSR Grant GF49620-92-J-0418) and computer time was generously provided by a SERDP at the NSCEE.


References

[1] Panton, R.I. "Incompressible Flow", John Wiley and Sons, New York, 1984.

[2] Lumley, J.L., (Editor). "Whither Turbulence? or Turbulence at the Crossroads", Lecture notes in Physics, vol. 357, Springer V., 345.

[3] Lienau, J.J., and Kollmann, W. "Numerical Simulation of the Trubulent Flow in Round Jets", 31st. AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, Jan. 11-14, 1993.

[4] Lienau, J.J., Kennedy, I.M., and Kollmann, W. "Numerical Simulation of Particle Dispersion in Turbulent Jets", 31st. AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, Jan. 11-14, 1933.

[5] Chen, J.H., Lienau, J.J., and Killmann, W. "Numerical Simulation of Low Re-number Turbulence in Round Jets", Ninth International Symposium on Turbulent Shear Flows, Kyoto, Japan, Aug. 16-18, 1993.

[6] Call, C.J., and Kennedy, I.M. "A Technique for Measuring Lagrangian and Eulerian Particle Statistics in a Turbulent Flow", Experiments in Fluids, 12, 125.


Topical Reports

Archive

by Sam West, Analyst in Charge

Archive (/archive) is a special file system that has been created by the NSCEE as the location of choice for very large files (> 250MB) that are to be archived from disk to a tape storage medium via the Data Migration Facility. The current disk size of the /archive file system is approximately 584,000 4K blocks or (2.39GB); however, the `virtual` size of this filesystem is only limited by NSCEE tape inventory.

The /archive file system is NFS-mounted on all NSCEE machines and serves as a file storage `sink' for NSCEE users. /archive contains directory hierarchies that mirror the NSCEE's user file system hierarchies below the file system name.

To simplify use of the /archive file system, all users have had a symbolic link named `archive' placed in their home directories. This link points to their corresponding directory in the /archive file system and can be used like any other directory.

A complete example of the preferred use of the /usr/tmp and /archive file systems follows (Note: With the exception noted, this example is valid in both bourne and c shells. Comments are placed to the right of the `#') (see table 1).

Table 1
% setenv MYTMPDIR 'tmpdir /usr/tmp' # create a temporary directory (C SHELL)
% MYTMPDIR='tmpdir /usr/tmp'; export MYTMPDIR # FOR BOURNE SHELL USERS
% cp myprog $MYTMPDIR/myprog # copy any necessary files to it
% cd $MYTMPDIR # change your working directory
% myprog > bigfile # execute your program
% mv bigfile $HOME/archive/bigfile # mv any big files to be migrated
% cd $HOME/archive # change your working directory
% dmput bigifle # migrate your big file

Note that the use of MYTMPDIR with the tmpdir(1) command insures that the files in the $MYTMPDIR directory will be clearned up after you have logged off, or your NQS job has exited (Please see local man page 'tmpdir').

Files can ONLY be migrated from file systems /archive, /u1 and /u2. The /tmp and /usr/tmp directories on the Cray are for temporary storage files only. The /archive file system is backed up on a daily basis. Prior to the daily backup of /archive, all migrated files are flushed to tape via the Data Migration Facility. Also, the size of /archive is trimmed, if necessary, to under 2 cartridge tapes' worth of data (~440MB) immediately prior to being backed up. This means that, after retrieval to /archive you should immediately move or copy large files to /usr/tmp for your use to prevent them from being re-migrated prematurely.

For further information, please see the man pages on archive(info), data_migration(info), usr_tmp(info) and tmpdir(1). For further information on NSCEE policies and practices, please refer to the NSCEE User Documentation available from NSCEE.


General Information

Dialing-In via Modem

For users with terminals, or personal computers, connection to the NSCEE telephone modems can be accomplished with a modem or through the campus network. The modem and communication software must be set for no parity, 8 bits per character, 1 stop bit and 1200, 2400,9600, or 14,400 baud.

To access NSCEE Computers you initially dial in to one of our modems at:

895-4154 (300 - 9600 baud modems), or
895-4155 (300 - 14,400 baud modems).

When your computer responds with CONNECT 1200, CONNECT 2400,CONNECT 9600, or CONNECT 14400, slowly hit the [enter] key a few times.

You will soon be connected and receive the prompt:

	NSCEE:

At this point, type in the command:

	rlogin hostname

to access any of the systems on the NSCEE network. The host names are given below.

	Example: rlogin nye.nscee.edu

The following list contains the desired host names for the computers in the Center and their IP numbers. All would fall under the domain name of "nscee.edu."

Computer Host Name IP Address
Cray Y-MP2/216 clark.nscee.edu 131.216.42.2
Sun MP 690 nye.nscee.edu 131.216.39.3
Convex C-220 aurora.nscee.edu 131.216.43.3

Electronic subscription renewal and account request.

To subscribe to SCENE:

%telnet nye.nscee.edu
%login:newscene
and answer the questions

To request a computer account:

%telnet nye.nscee.edu
%login:newuser
and answer the questions

NSCEE Directory

Information   (702) 895-4153
Operations Michael Ekedahl (702) 895-4150
User Support Joseph Lombardo (702) 895-4792
Networks Rick Pinson (702) 895-1493
Graphics Matthew Au (702) 895-4702
Cray Research Sam West (702) 895-4499
Modem Line 9600 baud (702) 895-4154
Modem Line 14,400 baud (702) 895-4155


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