Computational science is a field obsessed with convergence, with equations scripted to result in real-world numbers that minimize chance as much as possible. So, it may come as a surprise that Mary Wheeler – director of the ICES Centerfor Subsurface Modeling at The University of Texas at Austin, US – became a mathematician and computational scientist due to an incidental encounter.
“My roommate in college was taking a numerical analysis course. I would see her working on those problems, and think, ‘that’s interesting.’ And that’s how I first got involved,” says Wheeler, who, in the late 1950s, was enrolled at The University of Texas as a government major. “It happened by circumstance.”
That exposure ignited a chain of events, beginning with Wheeler adding a math major to her undergraduate studies. She has since published over 250 papers, and made significant advancements in developing algorithms for modeling subsurface flow.
This month Wheeler was awarded the John von Neumann Medal, the highest award bestowed by the United States Association for Computational Mechanics. Wheeler is the first woman to receive the honor, which celebrates outstanding achievements in computer-related science and technology. “It’s a very prestigious award,” Wheeler remarked. “And I’d like to say I’m excited because von Neumann has been one of my heroes in science.”
The area of subsurface modeling is a common thread uniting Wheeler’s research. “Your body is a subsurface and bones and breasts are a porous media. And the same mathematical models we use for a geological subsurface also apply to the subsurface of the body,” said Wheeler. “Mathematics is the language of sciences and how you communicate results.”
In the past, Wheeler has applied this mathematical lens towards understanding topics such as blood vessel formation and ground subsidence, where subsurface changes cause the Earth’s surface to cave-in or shift. Her most recent research aligns closely with two issues at the forefront of the energy industry – safely extracting oil and gas from the ground and storing combustion byproducts.
Wheeler is now developing a model showing the propagation of fractures induced in rock during the hydraulic fracturing process, and the ways water, chemicals, and natural gas flow through them. Understanding these processes plays an important role in informing fracturing methods that don’t disturb groundwater.
Research methods and the technology have changed immensely since the 1970s when Wheeler was a PhD student at Rice University in Houston, Texas. Then, scientists could only approach physics problems one dimensionally, with a maximum of 10 data elements and computer code written on paper punch cards.
Wheeler recalls her PhD advisors Henry Rachford Jr. and Jim Douglas Jr., both scientists at Humble (a predecessor of Exxon Mobil), developing a method to solve two-dimensional fluid flow problems. Some calculations required the use of computers in New York to carry out and complete.
“And now stop and think – that was just flow,” remarks Wheeler. “Now, we’re doing different phases, and you have mass transfer, and add that to the chemical, mechanical, and thermal reactions.”
In the 1970s, Wheeler worked on the IBM 650, the world’s first mass-produced computer. The machine resembled a refrigerator more than a modern computing system. In only 30 years, computational science has progressed to methods and machinery that outperform their predecessors exponentially.
The current problems Wheeler works with take into account three dimensions, may have more than one billion data elements, and require supercomputers that can analyze quadrillion operations per second.
Wheeler uses high-performance computing resources at the Texas Advanced Computing Center in Austin, US, the King Abdulla University of Science in Thuwal, Saudi Arabia, and IBM’s Watson, made famous by its victory on Jeopardy! in 2011.