First-order implicit time advance is used. A time-accurate mode is available, or local timestep scaling can be selected for acceleration to steady state. Grid sequencing and multigrid are also implemented for convergence acceleration.
Performance on the NAS Cray C-90 is 440 MFLOPS per processor; the code runs in a multitask mode with an average concurrency of 6 CPUs for three-dimensional problems. CPU time required is about 8 microseconds/point/iteration.
Memory required is 35 words per grid point of the largest grid block.
The integration procedure can be executed as a post-processor for the computed solutions, or run as an integral part of the OVERFLOW flow solver, returning a convergence history of the aerodynamic forces.
The author is William M. Chan.
Restrictions: PEGSUS is an Air Force restricted code. As such, one must obtain the original code from the Arnold Engineering Development Center (AEDC). AEDC distributes version 4.0; the NASA "enhancements" are referred to as version 4.1.
To receive the PEGSUS 4.0 software, the Air Force requires that your company be registered with the Defense Logistics Information Services Center as a "certified contractor" to receive export controlled data. To become registered, call 1-800-352-3572 and ask to complete DD form 2345. In the meantime, contact Ms. Bonnie Heikkinen at (931) 454-7885, or firstname.lastname@example.org, and she will fax you the AEDC software release forms. The certification number is required in the box referred to as export control number. After you complete the forms and fax them back to AEDC, it generally takes 1-2 weeks to get Air Force approval.
Once approval for PEGSUS 4.0 has been received from AEDC, the PEGSUS 4.1 Enhancements can be requested from NASA. (One can send both requests in at the same time; I will check with AEDC before releasing the NASA version.)
Note that distribution of the NASA version is restricted to those INDIVIDUALS who have Air Force approval.
Please write a letter (or email) of request for the desired code(s) to the appropriate developer(s) listed below. The letter should include a brief description of the application for which the codes will be used, and a list of those who will have access to the codes.
A completed software usage agreement form will be required as well, and may be available on the web. Once the request letter and agreement form are received and approval granted by NASA, a notification letter is sent to the requestor.
Code transmittal is generally in the form of a mime-encoded e-mail message; note that some of these codes are large. No anonymous FTP site is available; please make arrangements for this transfer.
Pieter G. Buning Configuration Aerodynamics Branch Mail Stop 499 NASA Langley Research Center Hampton, VA 23681-2199Software usage agreements will be sent upon receipt of the request letter.
William M. Chan MCAT, Inc. Mail Stop T27B-2 NASA Ames Research Center Moffett Field, CA 94035-1000A software usage agreement is available online.