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arXiv 2302.01013math.AP
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重力驱动二维Navier-Stokes-Korteweg模型的稳定性与不稳定性

On Stability and Instability of Gravity Driven Navier-Stokes-Korteweg Model in Two Dimensions

Fei Jiang, Fucai Li, Zhipeng Zhang

摘要:

Bresch-Desjardins-Gisclon-Sart在2008年基于线性化的二维Navier-Stokes-Korteweg方程推导出毛细作用可以减缓毛细流体中Rayleigh-Taylor(RT)不稳定性的增长速率。受他们的线性理论的启发,我们进一步研究了二维不可压Navier边界条件下的水平周期板区域的非线性RT问题,并严格验证了在我们的二维设置下,毛细作用可以抑制RT不稳定性。更精确地,如果RT密度分布$\barρ$满足附加的稳定化条件,则存在毛细作用系数的阈值$κ_{C}$,使得如果毛细作用系数$κ$大于$κ_{C}$,则RT平衡态周围的小扰动解在时间上是稳定的\emph{algebraically}。特别地,如果RT密度分布是线性的,则阈值$κ_{C}$可以由公式$κ_{C}=g /(π^2h^{-2}+L^{-2})\barρ'$给出,其中$2πL$表示板状域的周期单元在水平方向上的长度,并且$h$表示板状域的高度。此外,我们还给出了$κ\in[0,κ_{C})$的非线性不稳定性结果.不稳定性结果表明,如果毛细作用的强度太小,毛细作用不能抑制RT不稳定性。

英文摘要:

Bresch-Desjardins-Gisclon-Sart have derived that the capillarity can slow {down} the growth rate of Rayleigh-Taylor (RT) instability in the capillary fluids based on the linearized two-dimensional (2D) Navier-Stokes-Korteweg equations in 2008. Motivated by their linear theory, we further investigate the nonlinear RT problem for the 2D incompressible case in a horizontally periodic slab domain with Navier boundary condition, and rigorously verify that the RT instability can be inhibited by capillarity under our 2D setting. More precisely, if the RT density profile $\barρ$ satisfies an additional stabilizing condition, then there is a threshold $κ_{C}$ of capillarity coefficient, such that if the capillarity coefficient $κ$ is bigger than $κ_{C}$, then the small perturbation solution around the RT equilibrium state is \emph{algebraically} stable in time. In particular, if the RT density profile is linear, then the threshold $κ_{C}$ can be given by the formula $κ_{C}=g /(π^2h^{-2}+L^{-2})\barρ'$, where $2πL$ denotes the length of a periodic cell of the slab domain in the horizontal direction, and $h$ the height of the slab domain. In addition, we also provide a nonlinear instability result for $κ\in[0,κ_{C})$. The instability result presents that the capillarity can not inhibit the RT instability, if its strength is too small.

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