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September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Remembering ANS member Gil Brown
Brown
The nuclear community is mourning the loss of Gilbert Brown, who passed away on July 11 at the age of 77 following a battle with cancer.
Brown, an American Nuclear Society Fellow and an ANS member for nearly 50 years, joined the faculty at Lowell Technological Institute—now the University of Massachusetts–Lowell—in 1973 and remained there for the rest of his career. He eventually became director of the UMass Lowell nuclear engineering program. After his retirement, he remained an emeritus professor at the university.
Sukesh Aghara, chair of the Nuclear Engineering Department Heads Organization, noted in an email to NEDHO members and others that “Gil was a relentless advocate for nuclear energy and a deeply respected member of our professional community. He was also a kind and generous friend—and one of the reasons I ended up at UMass Lowell. He served the university with great dedication. . . . Within NEDHO, Gil was a steady presence and served for many years as our treasurer. His contributions to nuclear engineering education and to this community will be dearly missed.”
Matthew D. Zimmer, Igor A. Bolotnov
Nuclear Science and Engineering | Volume 194 | Number 8 | August-September 2020 | Pages 708-720
Technical Paper | doi.org/10.1080/00295639.2020.1722543
Articles are hosted by Taylor and Francis Online.
Recent advancements in computing power allow utilization of state-of-the-art direct numerical simulations (DNSs), coupled with interface tracking techniques, to perform fully resolved simulations of complex two-phase flows, such as flow regime transitions. Studying the highly resolved temporal and spatial information produced from these virtual experiments can advance our understanding of the phenomenon and inform coarser models. With these improved models, better predictions of flow regime behavior and location in boiling water reactors can be made.
The presented research uses the PHASTA code, which employs the level set method for interface tracking, to examine the mechanisms of flow regime transition, specifically the slug-to-bubbly and slug-to–churn-turbulent regime transitions. The DNS was validated using theoretical and experimental work found in open literature. Different geometries, including pipes and minichannels, were explored in order to improve the fundamental understanding of the complex flow phenomenon. Using advanced analysis techniques, the transient flow properties were analyzed at resolutions not available to other methods. The numerical data analysis allows for calculation of both time and spatially averaged properties as well as local instantaneous properties. Possible mechanisms for the transition are discussed. Examples include liquid kinetic energy/surface tension energy balance and interfacial shear forces in the liquid film. It is also noted that the transition out of slug flow can take at least two pathways: interfacial wave-induced instability development in the Taylor bubble, leading to its disintegration, or strong bubble shearing at the tail of the bubble.