Engineering-Physics Support

Dr. Nelson has 15 years experience in using, developing, maintaining, and modifying large scale engineering-physics computer codes. The codes, traditionally written in FORTRAN, often have a large about of legacy structure. These structures, which are typically buggy and incorrect, are well known by the few who use the code and thus function correctly for them, but very few others. Dr. Nelson is highly qualified and well versed at reverse engineering these older codes in order to verify the physics contained in them as well as uncovering and eliminating bugs that often have been hidden within the code for decades.

Some examples of the codes worked on and developed by Dr. Nelson are listed below.

• WINK: This binary star simulation program was originally written by David Wood. Dr. Nelson reverse engineered the code and subsequently found a number of errors in the underlying physics (based on errors in the source literature written by Kopal) as well as coding and logic errors that led the program to incorrectly identify the level of convergence.
• ZOOS: This 1D rad-hydro code was used primarily at the Los Alamos National Laboratory for modeling high speed energy deposition problems. The ZOOS code is typical of many legacy FORTRAN codes in requiring an in-depth understanding of the physics and modeling methods employed in such codes just to make use of them.
• RAM: This radioactive particulate transport code was written by Dr. Nelson for the Defense Nuclear Agency. The code employs numerical solutions to the Bateman equations for the calculation of radioactive decay products. Agglomeration, condensation, and evaporation models were used to simulate the mechanical behavior of the particulates.

These are just a few examples of the type of experience available from Valiant. If you have complex legacy FORTRAN code and need to understand it, modernize it, or even translate it into a newer language, then we have the expertise you need.

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06/20/00 ern