The daughter of an engineer, computational scientist Carol Woodward knew from an early age that she wanted to study mathematics and science and to attend graduate school. “I had some inspiring high school teachers who talked about how great it is to experience such intense study in one field. I knew that was what I wanted,” she says. At college, she explored various science majors, but mathematics, her first love, kept drawing her back.

An internship at Oak Ridge National Laboratory further set Carol on a career course that has proven both successful and fulfilling. There she first learned about high performance computing and met her future thesis advisor and several future colleagues. “It was a pivotal summer for me, and it really points to the value of internships, both personally and professionally,” she observes.

That summer experience, and her advisor’s suggestion, later prompted her to pursue postdoctoral study at another national lab after completing her Ph.D. in Computational and Applied Mathematics at Rice University. Carol recalls, “My advisor mentioned some interesting groundwater work going on at Livermore under Steve Ashby. I came and interviewed, and I loved the environment and the people.”

Carol joined the Lab’s Center for Applied Scientific Computing (CASC) in 1996, first as a postdoc and then as a staff researcher. CASC has developed a reputation over the years, she notes, as an organization that can solve tough problems, so she and her colleagues are asked to consult on a diverse array of projects. “It’s nice because it means I can work at the same place and not just do one thing for a long time—I get to keep changing what I work on,” she says.

Carol has also developed a problem-solving reputation over the years. In 2015 she was among the 15 early- and mid-career scientists and engineers recognized by the Lab for exceptional technical achievement, and in 2022 she was promoted to Distinguished Member of Technical Staff, the Lab’s highest technical job classification level. Her specialty is developing and delivering nonlinear solvers and time integration methods to the scientific simulation community. Carol has worked with numerous domain scientists to improve the efficiency and robustness of applications, allowing the first-ever or largest simulations in many different areas, from supernovae to groundwater flow.

In fact, some of Carol’s most impactful efforts have stemmed from the groundwater project that first drew her to the Lab. For instance, a novel nonlinear solution strategy she developed and implemented in the ParFlow code for modeling variably saturated subsurface flow in large-scale systems is now used worldwide for watershed simulation and climate analysis. ParFlow is currently used in a Department of Energy (DOE) project for watershed simulations of the continental U.S. “These are big models, and there’s some exciting math at play,” she notes.

Most prominently, Carol is the principal investigator for LLNL’s Suite of Nonlinear and Differential/Algebraic Solvers (SUNDIALS), an open-source package of time integrators and nonlinear solvers that garners more than 100,000 downloads annually and is used in myriad simulation-dependent applications. Her group’s technical contributions to the software have modernized it and upgraded its functionality for more than two decades, enabling it to scale to DOE’s highest-end computing systems. With its innovative solvers and flexibility for a variety of computing systems, SUNDIALS was awarded the prestigious 2023 Society for Industrial and Applied Mathematics (SIAM)/Association for Computing Machinery (ACM) Prize in Computational Science and Engineering. Carol states, “This award shows that our computational science community values the work put into delivering both efficient algorithms as well as their high-quality implementations into robust and usable software.”

Involvement in the broader computational science community is important to Carol. She serves on the editorial board for *ACM Transactions on Mathematical Software* and has chaired or served on numerous professional committees including the SIAM Council, the Association for Women in Mathematics Executive Committee, and the International Standing Committee for Gender Equality in Science. In addition, she served for four years as the SIAM Vice President at Large.

*—Holly Auten*