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The following guidelines are designed to support interactive users while maximizing system utilization, and the throughput of production batch jobs.
During such periods, these PEs will be dedicated to interactive work and will not be available to batch users. If two or more interactive users happen to be working at the time, they will share this pool of PEs.
In making your request, specify the period of time during which you will be working, and if you finish early, please let us know.
Special arrangements are also available for real-time demos, unusual debugging situations, short-term high-priority projects, etc. Contact ARSC consulting.
#QSUB -l mpp_t=30:00 # Request 30 minutes total MPP time #QSUB -l mpp_t=8:00:00 # Request 8 hours #QSUB -l mpp_t=2:15:00 # Request 2 hours and 15 minutesSee "man qsub" for details.
Two of our readers published some of their research (accomplished using the T3E) in the January edition of "Physics of Fluids." Here's an overview of the project, followed by the citation:
Jim Riley and Steve de Bruyn Kops of the University of Washington are testing new methods to predict turbulent and chemically reactive flows with direct numerical and large-eddy simulations. Turbulent flow research affects studies in a variety of areas, including the ozone layer in the atmosphere, the efficiency of fossil-fuel burning engines, and control of air pollution.The citation is:Turbulent flows are extremely difficult to simulate without resorting to modeling because of the massive processing power required to compute such complex events. In fact, Riley and de Bruyn Kops were the first researchers at ARSC to take advantage of all 256 processors on the ARSC Cray T3E, following the February 1999 upgrade.
To study turbulent combustion, de Bruyn Kops and Riley run direct numerical simulations (DNSs) of turbulent flows on massively parallel computers. In DNSs, the exact transport equations are solved numerically, without resorting to modeling. The computer code developed by de Bruyn Kops and Riley employs a pseudo-spectral scheme in which derivatives are computed in Fourier space and multiplication is performed in physical space. This method is both very accurate and computationally efficient.
As demonstrated in a recently published paper in Physics of Fluids, computers such as Yukon are finally powerful enough to simulate simple flows having the same conditions as those studied in wind tunnels.
The study of these "canonical flows," such as the scalar mixing layer discussed in the paper, enable researchers to develop theories and models that can be applied to more complex flows. In the laboratory, however, it is often very difficult to create an experiment that matches the desired conditions exactly because several parameters cannot always be adjusted independently. It is also not feasible to collect data as a function of three spatial dimensions plus time for large areas of the flow. As de Bruyn Kops and Riley discuss in their paper, both of these problems can be overcome in numerical experiments. If the simulations are closely matched to measured laboratory data, the results can be used with high confidence that they represent true physical phenomena, while providing extremely detailed information about the flow. From this solid base, the simulations can then be extended to include phenomena not present in the laboratory experiments, such as chemical reactions.
S. M. de Bruyn Kops and J. J. Riley, "Re-examining the thermal mixing layer with numerical simulations", Physics of Fluids, v12, n1, Jan. 2000.The abstract is available at:
http://staff.washington.edu/debk/node5.htmlThose with an on-line subscription to Physics of Fluids can find the complete paper at:
http://ojps.aip.org/journals/doc/PHFLE6-home/top.html
http://www.vcpc.univie.ac.at/aurora/overview.shtmlalong with a breakdown of all projects and goals. An extensive and interesting collection of papers from the past three years covers such work as:
http://www.vcpc.univie.ac.at/aurora/publications/.
A: {{ "mv -i" and "cp -i" only prompt when the move or copy would
{{ overwrite an existing file. "rm -i", on the other hand, prompts
{{ on EVERY file -- as expected!
{{
{{ How can I get "mv" and "cp" to ask about every file too, so I
{{ can issue wild-card commands like:
{{
{{ mv -i *.F90 ../some/directory
{{
{{ and then only move some of the files?
Well, you can't change "mv" and "cp," but you can use "find" to create
the desired behavior using the "-ok" option.
From "man find":
-ok cmd Like -exec except that the generated command line is
printed with a question mark first, and is executed only
if the user responds by typing y.
Here's the basic command:
find . -name "*.F90" -ok mv {} ../some/directory \;
And a sample run:
$ find . -name "*.f90" -ok mv {} ../some/directory \;
< mv ... ./out.f90 >? n
< mv ... ./int.f90 >? n
< mv ... ./Test2/out.f90 >? n
There's a problem here.
As the example shows, find doesn't stop at the current directory, but
recursively searches all subdirectories. Here are two ways to restrict
the search to the current directory:
find * \( -type d -prune \) -o \( -name "*.f90" -ok mv {} ../some/directory \; \)
find * \( -name "*.f90" -ok mv {} ../some/directory \; \) -o -prune
(For more on "-prune," see:
http://www.arsc.edu/support/news/T3Enews/T3Enews181.shtml#qt
Q: Is it a good idea to compress files which are to be DMF migrated?
[ Answers, questions, and tips graciously accepted. ]
Contact:
Donald Bahls ARSC User Consultant ph: 907-450-8674 Ed Kornkven ARSC HPC Specialist ph: 907-450-8669 Arctic Region Supercomputing Center University of Alaska Fairbanks PO Box 756020 Fairbanks AK 99775-6020
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