Harold Grad
New York University
January 23, 1923 - November 17, 1986
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Scientific Discipline: Applied Physical Sciences Membership Type:
Member
(elected 1970)
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Harold Grad was an applied mathematician and engineer whose research involved the application of statistical mechanics to kinetic theory, magnetohydrodynamics, and plasma physics. Much of Grad’s work was based on applications of the Boltzmann equation. One of his first findings, in 1963, was a set of 13 moment equations that interpreted the interpolation of levels of description between the Boltzmann equation and the equation of fluid dynamics. Grad was able to produce a mathematical proof of the asymptotic relationship of the Capman-Enskog and Hilbert expansions to actual solutions of the Boltzmann equation, as well as an existence theorem for the solutions of the Boltzmann equation. These studies played an important role in the understanding of fluids and plasmas and provided a significant model for the studies of hot plasmas. Grad was among the first to conduct studies in magnetohydrodynamics. He proposed a theorem that related the linear stability of a free-boundary configuration to the curvature of the boundary. Along with his theorem of nonexistence of finite smooth stable equilibria, the two theories led Grad to propose “Cusped Geometry” as a containment device for the high-temperature plasmas in a controlled thermonuclear reaction. These findings laid the foundation for modern plasma physics and magnetohydrodynamics.
Grad earned his B.E.E. degree from Cooper Union in 1943. He then received his M.S. and Ph.D. from New York University in 1945 and 1948, respectively. He began teaching mathematics at New York University in 1948, and he gained full professorship in 1957. In 1960, Grad founded the Magneto-Fluid Dynamics Division of the Courant Institute of Mathematical Sciences and remained its director for 25 years. He was a chairman in several scientific organizations, including the Fluid Dynamics Division of the American Physical Society (1963), the Plasma Physics Division of the American Physical Society (1968), and he was on the advisory committee of fusion energy for Oak Ridge National Laboratory (1964-’67, 1973-’76). In 1970, Grad was awarded the Boris Pregel Award from the New York Academy of Sciences for his mathematical contributions to the scientific community.
