Nonlinear effects in the combined Rayleigh-Taylor/Kelvin-Helmholtz instability

作者：Olson Britton J^*; Larsson Johan; Lele Sanjiva K; Cook Andrew W

来源：Physics of Fluids, 2011, 23(11): 114107.

DOI：10.1063/1.3660723

The combined Rayleigh-Taylor/Kelvin-Helmholtz (RT/KH) instability is studied in the early nonlinear regime. Specifically, the effect of adding shear to a gravitationally unstable configuration is investigated. While linear stability theory predicts that any amount of shear would increase the growth rate beyond the Rayleigh-Taylor value, numerical (large eddy) simulations show a more complex and non-monotonic behavior where small amounts of shear in fact decrease the growth rate. A velocity scale for the combined instability is proposed from linear stability arguments and is shown to effectively collapse the growth rates for different configurations. The specific amount of shear that minimizes the peak growth rate is identified and the physical origins of this non-monotonic behavior are investigated.

• 出版日期2011-11