Hartmann number
Physical key figure | |||||||||
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Surname | Hartmann number | ||||||||
Formula symbol | |||||||||
dimension | dimensionless | ||||||||
definition | |||||||||
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Named after | Julius Hartmann | ||||||||
scope of application | Magnetohydrodynamics |
The Hartmann number ( ) is a dimensionless number of fluids , i.e. gases or liquids . It is defined as the ratio between magnetically induced and viscous frictional forces .
The Hartmann number ( English Hartmann number ) - named after the Danish physicist Julius Hartmann (1881–1951) - plays an important role in the calculation and characterization of plasmas , such as those found in magnetohydrodynamics .
definition
- - Magnetic flux density
- - Characteristic length of the system
- - Electrical conductivity
- - dynamic viscosity
The square of the Hartmann number gives the Chandrasekhar number :
Individual evidence
- ^ R. Moreau et al .: Julius Hartmann and His Followers: A Review on the Properties of the Hartmann Layer. In: Magnetohydrodynamics Springer Netherlands, 2007, pp. 155–170. ISBN 978-1-4020-4832-6
- ^ X. Shan, D. Montgomery: On the role of the Hartmann number in magnetohydrodynamic activity . In: Plasma Physics and Controlled Fusion . tape 35 , no. 5 , 1993, p. 619-631 , doi : 10.1088 / 0741-3335 / 35/5/007 .
- ↑ U. Burr, U. Müller: Rayleigh-Bénard convection in liquid metal layers under the influence of a vertical magnetic field . In: Physics of Fluids . tape 13 , 2001, p. 3247-3257 , doi : 10.1063 / 1.1404385 .
literature
- Peter Kurzweil: The Vieweg Formula Lexicon. Vieweg + Teubner, Braunschweig 2002, p. 314 ISBN 3-528-03950-7 .