Clemson mathematician on team that received prestigious SIAM/ACM Prize 

Clemson University applied mathematician Timo Heister is among 14 scientists honored for their work on an open-source software library that empowers researchers worldwide to solve complex science and engineering problems.

Heister is one of the principal developers of deal.II, a powerful open-source finite element library of algorithms and data structures used by scientists in various fields to simulate physical phenomena on computers.

They received the 2025 Society for Industrial and Applied Mathematics (SIAM)/ Association for Computing Machinery (ACM) Prize in Computational Science and Engineering. The prize is a prestigious award given biennially to an individual or group that has made outstanding contributions to the development and use of mathematical and computational tools and methods for the solution of real-life science and engineering problems.

“I was elated that we received this award which confirms that what we’re doing is valuable for the science community,” Heister said. “Many scientists use the software as a tool, and what our work does is enable them to do their science.”

Heister said deal.II is used across many different sciences to help researchers understand some physical phenomena, such as how heat transfers or how stars behave in physics or why cells act the way they do in biology.

Across all sciences

“It’s not specific to mathematics or physics. It’s across all sciences. There are people who model the decay of statutes from ancient Rome, people who model the growth of the roots of plants. Others do molecular dynamics or solid mechanics engineering to determine how much weight a bridge can carry,” Heister said, “and everything in between.”

Many times, scientists must simulate these processes on a computer through modeling because conducting actual experiments is not possible.

“Most processes in nature involve some kind of basic physical laws, such as conservation of energy or conservation of momentum,” he said. “Many of them can be described by differential equations in some shape or form.”

Every differential equation is different, and Heister compares deal.II to a “big collection of Lego bricks with some assembly required.”

New numerical methods

Heister’s research centers around numerical analysis and the numerical solution of partial differential equations using the finite element method focusing on efficient solvers that scale to massively parallel supercomputers. His work is used to develop new numerical methods and to solve problems across a wide range of scientific disciplines.

The deal.II library started as a small project by two researchers, Wolfgang Bangerth and Guido Kanschat, at Heidelberg University in Germany in the 1990s. It quickly became an influential library. 

Heister started using it as a graduate student in the 2000s, but there were things it could not do at the time. “I wanted to solve larger problems than others had solved at that time with this library,” said Heister, who designed and implemented the advanced parallel algorithms that allow deal.II to harness the power of the largest supercomputers today. 

Heister eventually completed a postdoctoral fellowship at Texas A&M, the school where Bangerth and Kanschat worked at the time, before joining the Clemson faculty in 2013.

Since 1998, deal.II has been used for computations in more than 2,500 scientific papers.