Editing Fluid dynamics (section)

== Multidisciplinary types ==

===Flows according to Mach regimes===
{{Main|Mach number}}
While many flows (such as flow of water through a pipe) occur at low [[Mach number]]s ([[Speed of sound|subsonic]] flows), many flows of practical interest in aerodynamics or in [[Turbomachinery|turbomachines]] occur at high fractions of {{math|[[Mach number|''M'' {{=}} 1]]}} ([[Transonic|transonic flows]]) or in excess of it ([[Supersonic speed|supersonic]] or even [[Hypersonic speed|hypersonic flows]]). New phenomena occur at these regimes such as instabilities in transonic flow, shock waves for supersonic flow, or non-equilibrium chemical behaviour due to ionization in hypersonic flows. In practice, each of those flow regimes is treated separately.

===Reactive versus non-reactive flows===
Reactive flows are flows that are chemically reactive, which finds its applications in many areas, including [[combustion]] ([[Internal Combustion Engine|IC engine]]), [[propulsion]] devices ([[rockets]], [[jet engines]], and so on), [[detonations]], fire and safety hazards, and astrophysics. In addition to conservation of mass, momentum and energy, conservation of individual species (for example, mass fraction of [[methane]] in methane combustion) need to be derived, where the production/depletion rate of any species are obtained by simultaneously solving the equations of [[chemical kinetics]].

===Magnetohydrodynamics===
{{Main|Magnetohydrodynamics}}
[[Magnetohydrodynamics]] is the multidisciplinary study of the flow of [[electrical conduction|electrically conducting]] fluids in [[Electromagnetism|electromagnetic]] fields. Examples of such fluids include [[Plasma (physics)|plasma]]s, liquid metals, and [[Saline water|salt water]]. The fluid flow equations are solved simultaneously with [[Maxwell's equations]] of electromagnetism.

===Relativistic fluid dynamics===
Relativistic fluid dynamics studies the macroscopic and microscopic fluid motion at large velocities comparable to the [[velocity of light]].<ref>{{cite book |last1=Landau |first1=Lev Davidovich |author1-link=Lev Landau|author2-link=Evgeny Lifshitz|first2=Evgenii Mikhailovich |last2=Lifshitz |title=Fluid Mechanics |location=London |publisher=Pergamon |year=1987 |isbn=0-08-033933-6 }}</ref> This branch of fluid dynamics accounts for the relativistic effects both from the [[special theory of relativity]] and the [[general theory of relativity]]. The governing equations are derived in [[Riemannian geometry]] for [[Minkowski spacetime]].

=== Fluctuating hydrodynamics ===
This branch of fluid dynamics augments the standard hydrodynamic equations with stochastic fluxes that model 
thermal fluctuations.<ref>{{ cite book | last1= Ortiz de Zarate | first1= Jose M. | last2= Sengers | first2= Jan V. | title= Hydrodynamic Fluctuations in Fluids and Fluid Mixtures | publisher= Elsevier | location= Amsterdam | year= 2006}}</ref>
As formulated by [[Lev Landau|Landau]] and [[Evgeny Lifshitz|Lifshitz]],<ref>{{ cite book |last1=Landau |first1=Lev Davidovich |author1-link=Lev Landau|author2-link=Evgeny Lifshitz|first2=Evgenii Mikhailovich |last2=Lifshitz |title=Fluid Mechanics |location=London |publisher=Pergamon |year=1959 }}</ref>
a [[white noise]] contribution obtained from the [[fluctuation-dissipation theorem]] of [[statistical mechanics]]
is added to the [[viscous stress tensor]] and [[heat flux]].