Naslov
Laser generated richtmyer-meshkov and rayleigh-taylor instabilities and nonlinear wave-vortex paradigm in turbulent mixing: ii. Near-central region of gaussian spot
(Laser generated richtmyer-meshkov and rayleigh-taylor instabilities and nonlinear wave-vortex paradigm in turbulent mixing: ii. near-central region of gaussian spot)

Autori
Lugomer, Stjepan

Izvornik
Laser and particle beams (0263-0346) 35 (2017), 2; 210-225

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Laser ablation, Richtnyer-Meshkov instability, Rayleigh-Taylor instability, solitary waves, coherent structures, turbulent mixing, vortex filaments, wave-vortex phenomena

Sažetak
Laser-induced three-dimensional (3D) Richtmyer-Meshkov (RM) and Rayleigh-Taylor (RT) instabilities on metal target in the semiconfined configuration (SCC) show the new paradigm of wave-vortex mixing. The SCC enables extended lifetime of a hot vapor/plasma plume above the target surface and the formation of fast multiple reshocks. This causes - in the Central Region (CR) of Gaussian-like spot - the evolution of RMI with the spike breakup (Lugomer, 2016), while in the Near Central Region (NCR) causes the RMI followed by the RTI. The density interface is transformed into the large-scale broken irregular, quasi-periodic web which comprises the RTI mushroom-shape spikes and the coherent wave-vortex structures like the line solitons and vortex filaments. The intensity and direction of reshocks change (due to irregularity of the interface) and cause the formation of domains with the weak and the strong reshocks effects. The weak reshocks affect mushroom shape spikes only slightly, while the strong ones cause their deformation and symmetry break, bubble collapse, and separation of the horizontal flow into vortex ribbons. Interaction of ribbons with spikes and bubbles causes the ribbon pinning, looping, winding and formation of knotted and tangled structures. The line solitons, vortex filaments and ribbons tend to organize into complex large-scale structures with the low wave-vortex turbulent mixing. They represent the new paradigm of 3D Richtmyer-Meshkov and Rayleigh-Taylor instabilities in which the transition to the small scale turbulent mixing does not appear.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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