The Richtmyer–Meshkov instability (RMI) occurs when two fluids of different density are impulsively accelerated. Normally this is by the passage of a
shock wave
In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a me ...
. The development of the
instability
In numerous fields of study, the component of instability within a system is generally characterized by some of the outputs or internal states growing without bounds. Not all systems that are not stable are unstable; systems can also be mar ...
begins with small amplitude perturbations which initially grow linearly with time. This is followed by a nonlinear regime with bubbles appearing in the case of a light fluid penetrating a heavy fluid, and with spikes appearing in the case of a heavy fluid penetrating a light fluid. A chaotic regime eventually is reached and the two fluids mix. This instability can be considered the impulsive-acceleration limit of the
Rayleigh–Taylor instability
The Rayleigh–Taylor instability, or RT instability (after Lord Rayleigh and G. I. Taylor), is an instability of an interface between two fluids of different densities which occurs when the lighter fluid is pushing the heavier fluid.
Drazin ( ...
.
History
R. D. Richtmyer provided a theoretical prediction, and E. E. Meshkov (Евгений Евграфович Мешков)
( ru) provided experimental verification. Materials in the cores of stars, like Cobalt-56 from
Supernova 1987A were observed earlier than expected. This was evidence of mixing due to Richtmyer–Meshkov and
Rayleigh–Taylor instabilities.
Examples
During the implosion of an
inertial confinement fusion
Inertial confinement fusion (ICF) is a fusion energy process that initiates nuclear fusion reactions by compressing and heating targets filled with thermonuclear fuel. In modern machines, the targets are small spherical pellets about the size of ...
target, the hot shell material surrounding the cold
D-
T fuel layer is shock-accelerated. This instability is also seen in
Magnetized target fusion
Magnetized Target Fusion (MTF) is a fusion power concept that combines features of magnetic confinement fusion (MCF) and inertial confinement fusion (ICF). Like the magnetic approach, the fusion fuel is confined at lower density by magnetic fields ...
.
["On the collapse of a Gas Cavity by an Imploding Molten Lead Shell and Richtmyer-Meshkov Instability" Victoria Suponitsky, et al. General Fusion Inc, 2013] Mixing of the shell material and fuel is not desired and efforts are made to minimize any tiny imperfections or irregularities which will be magnified by RMI.
Supersonic combustion in a
Scramjet
A scramjet (supersonic combustion ramjet) is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully ...
may benefit from RMI as the fuel-oxidants interface is enhanced by the breakup of the fuel into finer droplets. Also in studies of
deflagration to detonation transition
Deflagration to detonation transition (DDT) refers to a phenomenon in ignitable mixtures of a flammable gas and air (or oxygen) when a sudden transition takes place from a deflagration type of combustion to a detonation type of explosion.
Descr ...
(DDT) processes show that RMI-induced flame acceleration can result in detonation.
See also
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Rayleigh–Taylor instability
The Rayleigh–Taylor instability, or RT instability (after Lord Rayleigh and G. I. Taylor), is an instability of an interface between two fluids of different densities which occurs when the lighter fluid is pushing the heavier fluid.
Drazin ( ...
*
Mushroom cloud
A mushroom cloud is a distinctive mushroom-shaped flammagenitus cloud of debris, smoke and usually condensed water vapor resulting from a large explosion. The effect is most commonly associated with a nuclear explosion, but any sufficiently ener ...
*
Plateau–Rayleigh instability
The Plateau–Rayleigh instability, often just called the Rayleigh instability, explains why and how a falling stream of fluid breaks up into smaller packets with the same volume but less surface area. It is related to the Rayleigh–Taylor insta ...
*
Salt fingering
*
Kármán vortex street
In fluid dynamics, a Kármán vortex street (or a von Kármán vortex street) is a repeating pattern of swirling vortices, caused by a process known as vortex shedding, which is responsible for the unsteady separation of flow of a fluid arou ...
*
Kelvin–Helmholtz instability
The Kelvin–Helmholtz instability (after Lord Kelvin and Hermann von Helmholtz) is a fluid instability that occurs when there is velocity shear in a single continuous fluid or a velocity difference across the interface between two fluids. K ...
*
Hydrodynamics
References
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External links
Wisconsin Shock Tube LaboratoryNew type of interface evolution in the Richtmyer–Meshkov instabilityRecent Advances in Indirect Drive ICF Target Physics at LLNL
*
ttps://web.archive.org/web/20050125073538/http://www.td.mw.tum.de/tum-td/de/forschung/pub/CD_Mayinger/339.pdf Propagation of Fast Deflagrations and Marginal Detonations in Hydrogen-Air MixturesMushrooms+Snakes: a visualization of Richtmyer–Meshkov instability*
ttp://web.arizona.edu/~fluidlab/ Experiments on the Richtmyer–Meshkov instability at the University of Arizona
{{DEFAULTSORT:Richtmyer-Meshkov instability
Fluid dynamics
Plasma instabilities
Astrophysics
Fluid dynamic instabilities