Houston and Austin

The subsurface modeling techniques developing in Houston were naturally addressed as part of David Young’s UT Austin course on numerical analysis, where Mary Wheeler first began working with them on the UT CDC 1604 in the early sixties. Dynamic partial differential equations are used to model transient time-varying physical processes, with the classic example being the two-dimensional heat flow equation. In the realm of computational geosciences, these equations are used to model and simulate transient fluid flow and transport through porous media, predicting how oil, gas, or groundwater move over time. Solving these massive, multidimensional time-dependent equations with early computers was difficult until the Alternating Direction Implicit method was created to break them down into simpler, one-dimensional steps. Wheeler dedicated her 1963 master's thesis at UT to rigorously analyzing the mathematical properties of ADI, which had been developed a decade earlier by Douglas, Rachford, and Donald Peaceman at Exxon precursor Humble Oil to solve PDEs on the severely memory-constrained IBM CPC. [1][2]

Wheeler's work at UT served as an introduction to Henry Rachford and Jim Douglas, both of whom had transitioned from Humble Oil to Rice and made it a center for the computational modeling and simulation associated with the oil industry. Rachford served as Wheeler's doctoral advisor at Rice. Under his guidance, she moved into the field of subsurface flow problems, discovering a passion for environmental applications that would define her career. Her work at Rice was also guided by Douglas, who recognized her analytical skills and became a lifelong mentor. They were establishing the computational foundations for simulating fluid flow in underground porous media and their mentorship was the defining influence on Wheeler's career trajectory and research philosophy. She frequently cited them as the fathers of the field who taught her the importance of combining theoretical depth with practical utility. Together, this group became one of the most influential teams in numerical analysis during the seventies, coauthoring significant papers, such as research on superconvergence and procedures for flux modeling. 

These were important connections between computing at UT Austin, Exxon, Rice, and Houston. Mary Wheeler became involved at UT in the early sixties before moving to Rice, and then returning to UT in the nineties. Another sign was the story of how Humble Oil donated its IBM CPC to UT in 1958. UT’s Al Matsen was a consultant for Exxon Houston and New Jersey for over thirty-five years. The CPC was a landmark gift and a direct result of Matsen’s extensive ties. To bypass bureaucratic paperwork, Matsen, his graduate students, and other faculty physically carried the heavy components into Welch Hall and installed it themselves. Exxon had acquired the CPC in 1952 and used it heavily for creation of the ADI techniques. 

The history of SOR Successive Over-Relaxation and the work of David Young at TRW and UT was focused on fluid and heat flows for atmospheric reentry vehicles. At the same time, ADI and the work of Peaceman, Rachford, and Douglas in Houston was focused on fluid and heat flows for the oil industry. The nature of the modeling and the computing hardware was similar, the approaches involved in ADI and SOR were complementary. Mary Wheeler was a direct bridge between the two, beginning with David Young in Austin in the early sixties, moving over to Houston and ADI for several decades, then returning to Austin in the nineties.

Mary Wheeler

Henry Rachford and the IBM CPC at Exxon precursor Humble Oil in Houston, circa 1953.

David Young

[1] Wonderful retrospective about Rachford, Douglas, Peaceman, and ADI in Houston. 

[2] Retrospective on Mary Wheeler's career.

[3] Numerical Linear Algebra special edition dedicated to David Young. Note especially the context around Charles Warlick.

David's first job after graduating from Harvard was as an Applied Mathematician in the Computing Laboratory of the Aberdeen Proving Ground, Maryland, during 1950–1951. His fellow co-workers included Samuel Conte, Charles Warlick, and Mario Juncosa, among others. During this time, David and Mildred purchased their first new house, and had their first son, William David. At that time, Aberdeen Proving Ground contained one of the largest collections of electronic computers in the U.S. They were employed in the Ballistics Research Laboratory, primarily for the calculation of bombing and firing tables. Some of the computers that were being used at BRL included the ENIAC, which was the first general- purpose electronic computer, the ORDVAC, which was designed by John von Neumann who often visited Aberdeen Proving Ground, the EDVAC, which was a rotating drum computer, and a Bell Laboratory paper tape-driven computer. David Young and Charles Warlick worked on the ORDVAC computer using Richardson's method on a 21 x 21 grid, which required writing a tricky computer program, at that time, because the machine had a total memory of only 1024 40-bit words with no external memory. 

The University of Texas in Austin wanted to establish a Computation Center. Professor Robert Greenwood, and others from the Department of Mathematics, wrote to David, inviting him to come to Texas. At first, David dismissed the offer, because he considered Texas to be an outback area of the country. Eventually, he decided to go and take a look for himself. He was pleasantly surprised to find that Austin was quite a nice city, with a river, hills, and oak trees, as well as having a good university. Lou Ehrlich followed David from Maryland to California to Texas, and became his first PhD student in 1963. In the summer of 1958, David moved his family to Austin-he would spend the rest of his career there. David and Mildred's third child, Carolyn Ellen, was born in Austin.

In the Fall of 1958, David brought Bob Gregory to Texas to join him as a member of the mathematics faculty, and to help him set up the Computation Center-which was almost non-existent. David, Bob, and a secretary shared an office next to the computer room. The first computer was an IBM 650 Magnetic Drum Data Processing Machine, which was the world's first mass-produced computer. During the next several years, Young and Gregory purchased new computers, expanded the staff, and designed a new building for the Center, which was built partially underground near the University tower. In 1965, David asked Charles Warlick to move to Austin, and to help him run the expanding operations of the Computation Center.

Under David's leadership, The University of Texas not only built a new Computation Center building, but also acquired two large supercomputer systems-the CDC 1604 computer in 1960, and the CDC 6600 computer in 1966. Gregory was particularly interested in the CDC computers because of their long 60 bit word length. Based on his reputation, David obtained the first $400,000 grant, from the National Science Foundation, toward the purchase of the CDC 1604 computer, which was one of the first transistorized computers. The CDC 6600 supercomputer, which was one of the largest and fastest computers at that time, was purchased with the help of the first NSF million dollar equipment grant.