Banerjee’s area of expertise is in Rayleigh-Taylor instability, a phenomenon which occurs between materials of different densities when the density and pressure gradients are in opposite directions creating an unstable stratification.
“In the presence of gravity—or any accelerating field—the two materials penetrate one another like ‘fingers,'” Banerjee said in a statement.
Investigating this kind of instability is extremely challenging because it happens almost in an instant and the large measurement uncertainties of accelerated solids.
For their study, Banerjee and colleagues poured Hellman’s Real Mayonnaise into a Plexiglass container and then accelerated the sample inside a rotating wheel. The progress of the material was tracked with a 500fps high-speed camera, whose images were fed into an image processing algorithm that could detect parameters associated with Rayleigh-Taylor instability. The wavelength and amplitude growth rates were finally compared to existing analytical models.
These experiments allowed the research team to visualize both the elastic-plastic and instability evolution of the material. The authors concluded that the onset of the instability (“instability threshold”) was related to the size of the amplitude (perturbation) and wavelength (distance between crests of a wave) applied.
“There has been an ongoing debate in the scientific community about whether instability growth is a function of the initial conditions or a more local catastrophic process,” says Banerjee. “Our experiments confirm the former conclusion: that interface growth is strongly dependent on the choice of initial conditions, such as amplitude and wavelength.”
In the future, these findings will help researchers design better conditions for inertial confinement. Step by step, little by little, the world is moving closer to achieving nuclear fusion. On that note, researchers have triggered fusion before — it’s just that the energy required to trigger the reaction was larger than the energy produced by it. Some of the most promising fusion reactors include the International Thermonuclear Experimental Reactor (ITER) in France and the Wendelstein 7-X reactor in Germany.
The findings appeared in the journal Physical Review E.