62 / 2020-02-28 19:18:22

Stretching/compression effects in interfacial fluid mixing induced by complex waves

interfacial fluid mixing,stretching/compression,wave

全体主题 > 极端条件下的物理学

Interfacial fluid mixing induced by complex wave structures, such as shock, rarefaction and compression waves, plays a fundamental role in engineering applications, such as inertial confinement fusion, and in natural phenomena, such as supernova. In most of the previous research, scientists have focused on two well-known mechanisms, i.e., the Richtmyer-Meshkov effect, which is induced by the motions inherited from the historical stages, and the Rayleigh-Taylor effect, which is caused by the overall acceleration (or deceleration) of the mixing zone. In the present work, a third mechanism is identified, i.e., stretching (or compression) effect caused by mean-velocity difference between two ends of the mixing zone, which arises during the propagation of waves. It turns out that during the rarefaction waves, the mixing zone is stretched while during the compression waves or shock waves, the mixing zone is compressed. To illustrate the three effects, a physical model of Richtmyer-Meshkov instability with reshock is used, which involves shock, rarefaction and compression waves in a single case. An analytical formula is proposed for the new effect. By combining these three effects, the entire evolution of mixing width is restructured, which agrees well with numerical simulations for problems with a wide range of density ratios.