Harold Grad (January 23, 1923 in New York City – November 17, 1986) was an American applied mathematician. His work specialized in the application of statistical mechanics to plasma physics and magnetohydrodynamics.
In statistical mechanics he had developed in his thesis new methods for the solution of the Boltzmann equation. He derived the Boltzmann equation from Liouville equation using BBGKY hierarchy under certain limits, known as Boltzmann–Grad limit. Harold Grad was the founder of the Magneto-fluid Dynamics Division of the Courant Institute and served as its head until shortly before his death From 1964 to 1967 and 1974 to 1977 he was a member of the Advisory Committee for Fusion Energy at Oak Ridge National Laboratory.
In 1986, he received the James Clerk Maxwell Prize in Plasma Physics from the American Physical Society. In 1970 he became a member of the National Academy of Sciences. He was an invited speaker at the International Congress of Mathematicians in Nice in 1970 and in Stockholm in 1962.
The Courant Institute offers the Harold Grad Memorial Prize to outstanding performance and promise as a graduate student.
Dr. Grad received a bachelors in electrical engineering from the Cooper Union in 1943 and his masters at New York University, in 1945. Grad did his doctoral work under Richard Courant and graduated in 1948. His thesis was on the approximation of the Boltzmann Equation by torque. He was then at the Courant Institute of Mathematical Sciences of New York University from 1948 as associate professor and from 1957 until his death. Dr. Grad conducted research in magnetohydrodynamics, the mathematical formulation of plasma physics and applications of plasma physics to nuclear fusion. He led the magnetohydrodynamics department from 1956 until 1980. He was awarded Eringen Medal in 1982.
- Grad, H. (1949). On the kinetic theory of rarefied gases. Communications on pure and applied mathematics, 2(4), 331-407.
- "NYU > Courant Institute > About > Student Prizes". Cims.nyu.edu. Archived from the original on 2014-02-27. Retrieved 2014-06-14.
- Blank, Albert A. (1987). "Harold Grad". Phys. Today. 40 (3): 86. doi:10.1063/1.2819960.
- J Berowitz, H Grad and H Rubin, in proceedings of the second United Nations International conference on peaceful uses of atomic energy, Geneva, 1958, Vol 31, Page 177
- Grad, Harold (December 1, 1957). "Theory of Cusped Geometries, I. General Survey NYO-7969". Inst. Math. Sci., N.Y.U.
- Containment in a cusped Plasma System, Dr. Harold Grad, NYO-9496
- Grad, Harold. "Mathematical problems arising in plasma physics." Actes, Congrès int. Math., Nice, 1970. Tome 3: 105–114.