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Magnetohydrodynamics (MHD) (''magneto fluid dynamics'' or ''hydromagnetics'') is the study of the magnetic properties of electrically conducting fluids. Examples of such magneto-fluids include plasmas, liquid metals, and salt water or electrolytes. The word ''magnetohydrodynamics (MHD)'' is derived from ''magneto-'' meaning magnetic field, ''hydro-'' meaning water, and ''-dynamics'' meaning movement. The field of MHD was initiated by Hannes Alfvén, for which he received the Nobel Prize in Physics in 1970. The fundamental concept behind MHD is that magnetic fields can induce currents in a moving conductive fluid, which in turn polarizes the fluid and reciprocally changes the magnetic field itself. The set of equations that describe MHD are a combination of the Navier-Stokes equations of fluid dynamics and Maxwell's equations of electromagnetism. These differential equations must be solved simultaneously, either analytically or numerically. == History == The first recorded use of the word ''magnetohydrodynamics'' is by Hannes Alfvén in 1942: :"At last some remarks are made about the transfer of momentum from the Sun to the planets, which is fundamental to the theory (§11). The importance of the magnetohydrodynamic waves in this respect are pointed out."〔Alfvén, H., "(On the cosmogony of the solar system III", ''Stockholms Observatoriums Annaler )'', vol. 14, pp.9.1-9.29〕 The ebbing salty water flowing past London's Waterloo Bridge interacts with the Earth's magnetic field to produce a potential difference between the two river-banks. Michael Faraday tried this experiment in 1832 but the current was too small to measure with the equipment at the time,〔(Dynamos in Nature ) by David P. Stern〕 and the river bed contributed to short-circuit the signal. However, by a similar process the voltage induced by the tide in the English Channel was measured in 1851.〔McKetta J McKetta, "(Encyclopedia of Chemical Processing and Design: Volume 66 )" (1999)〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「magnetohydrodynamics」の詳細全文を読む スポンサード リンク
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