studied by Lord Rayleigh. The important insight by G. I. Taylor was his realisation that this situation is equivalent to the situation when the fluids are , with the less dense fluid accelerating into the denser fluid. This occurs deep underwater on the surface of an expanding bubble and in a nuclear explosion.
As the RT instability develops, the initial perturbations progress from a linear growth phase into a non-linear growth phase, eventually developing "plumes" flowing upwards (in the gravitational buoyancy sense) and "spikes" falling downwards. In the linear phase, the fluid movement can be closely approximated by , and the amplitude of perturbations is growing exponentially with time. In the non-linear phase, perturbation amplitude is too large for a linear approximation, and equations are required to describe fluid motions. In general, the density disparity between the fluids determines the structure of the subsequent non-linear RT instability flows (assuming other variables such as surface tension and viscosity are negligible here). The difference in the fluid densities divided by their sum is defined as the , A. For A close to 0, RT instability flows take the form of symmetric "fingers" of fluid; for A close to 1, the much lighter fluid "below" the heavier fluid takes the form of larger bubble-like plumes.
This process is evident not only in many terrestrial examples, from to , but also in and . For example, RT instability structure is evident in the , in which the expanding powered by the is sweeping up ejected material from the explosion 1000 years ago. The RT instability has also recently been discovered in the Sun's outer atmosphere, or , when a relatively dense overlies a less dense plasma bubble. This latter case resembles magnetically modulated RT instabilities.
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Note that the RT instability is not to be confused with the (also known as Rayleigh instability) of a liquid jet. This instability, sometimes called the hosepipe (or firehose) instability, occurs due to surface tension, which acts to break a cylindrical jet into a stream of droplets having the same total volume but higher surface area.
Many people have witnessed the RT instability by looking at a , although some might claim this is more accurately described as an example of due to the active heating of the fluid layer at the bottom of the lamp.
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Equation text test
The RT instability can be seen as the result of created by the misalignment of the pressure and density gradients at the perturbed interface, as described by the two-dimensional equation, DωDt=1ρ2?ρ×?p,
GIF test