The Bullard‐Gellman dynamo, presented by Edward Crisp Bullard (q.v.) and Harvey Gellman in a pioneering paper of 1954, was the first convincing quantitative model for dynamo action in a fluid sphere. It prescribed a specific velocity, intended as a highly idealized model of the motion in the Earth's core, and considered the kinematic growth of magnetic field produced by this flow (see Dynamos, kinematic ). Bullard and Gellman considered this problem both theoretically and computationally. In terms of the dynamo explanation for the Earth's magnetic field, this work was ground‐breaking in several respects.
The study was formulated using the mathematical framework of vector spherical harmonics (q.v.). In representing the magnetic field and the velocity in this form—and in analyzing the induction equation determining the time‐evolution of magnetic field in the same terms—Bullard and Gellman introduced the formalism most commonly used for dynamo theory today. (A similar treatment had...
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Bibliography
Backus, G.E., 1958. A class of self‐sustaining dissipative spherical dynamos. Annals of Physics, 4: 372–447.
Bullard, E.C., and Gellman, H., 1954. Homogeneous dynamos and terrestrial magnetism. Proceedings of the Royal Society of London, Series A, 247: 213–278.
Elsasser, W.M., 1946. Induction effects in terrestrial magnetism: Part I. Theory. Physical Review, 69: 106–116.
Kumar, S., and Roberts, P.H., 1975. A three‐dimensional kinematic dynamo. Proceedings of the Royal Society of London, Series A, 344: 235–258.
Lilley, F.E.M., 1970. On kinematic dynamos. Proceedings of the Royal Society of London, Series A, 316: 153–167.
Parker, E.N., 1955. Hydromagnetic dynamo models. Astrophysical Journal, 121: 293–314.
Sarson, G.R., 2003. Kinematic dynamos driven by thermal wind flows. Proceedings of the Royal Society of London, Series A, 459: 1241–1259.
Takeuchi, H., and Shimazu, Y., 1953. On a self‐exciting process in magneto‐hydrodynamics. Journal of Geophysical Research, 58: 497–518.
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Sarson, G.R. (2007). Dynamo, Bullard‐Gellman. In: Gubbins, D., Herrero-Bervera, E. (eds) Encyclopedia of Geomagnetism and Paleomagnetism. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-4423-6_71
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