### magnetohydrodynamics

**(MHD)**
(dynamics of electrically conducting fluids)

**Magnetohydrodynamics** (**MHD**) is fluid dynamics that
includes the effects of electrical conductivity
of the fluids.
(Note that the term MHD is definitely used for compressible fluids,
even though the term "hydrodynamics" is sometimes used
specifically to indicate fluid dynamics of non-compressible fluids.)
The field was initiated by Hannes Alfvén who
coined the word in the 1940s.
It specifically deals with the acceleration of the fluid due to
electromagnetic (EM) forces, including those EM forces resulting from that
acceleration, but approximation methods assuming some of these
forces are negligible can be useful.
In its full form, it more-or-less consists of the combination
of fluid dynamics' Navier-Stokes equations and electrodynamics'
Maxwell's equations.

Applications in astrophysics include
modeling plasma in the
interplanetary medium and interstellar medium
as well as star models, both the interior
and the atmosphere.
Such a system involving plasma is sometimes termed
a **magneto-plasma system**.
Other applications include geophysics (the fluid interior
of the Earth), engineering and medicine.

In some astrophysical phenomena,
the electrical resistance is minor and
its MHD can be effectively simplified by ignoring it.
The phrase **resistive MHD** indicates that
electrical resistance is specifically included.
Among the other variants is **Hall MHD** (**HMHD**),
taking into account the Hall effect.

(*physics,magnetism,fluid dynamics*)
**Further reading:**

http://en.wikipedia.org/wiki/Magnetohydrodynamics

https://events.spacepole.be/event/43/attachments/187/366/sidc_basic_talk_10_-_Slides.pdf

**Referenced by pages:**

Alfvén wave

alpha disk

AREPO

AstroBEAR

Athena

computational astrophysics

current sheet

dynamo

Enzo

Faraday rotation

FLASH

hydrodynamics

Lorentz force

MagIC

magnetic induction

N-body simulation

Navier-Stokes equations (NS equations)

plasma astrophysics

PLUTO Code

shearing box

shock wave

spiral density wave

turbulent pressure

Index