Nonlinear Stability of the Rayleigh-Taylor Problem in Quantum Navier-Stokes Equations
Fei Jiang, Yajie Zhang, Zhipeng Zhang, Youyi Zhao
TL;DR
The paper tackles nonlinear Rayleigh–Taylor instability for the quantum Navier–Stokes system in a slab, showing that quantum stabilization via the Bohm potential yields nonlinear stability when the scaled Planck constant $\varepsilon$ exceeds a finite threshold $\varepsilon_c$, under a stabilizing density profile. The authors develop a novel multi-layer energy method with anisotropic spatial norms, establishing a sequence of a priori estimates that control high-order, tangential, and negative-derivative quantities and yield algebraic decay. A bootstrap argument closes the estimates, proving global existence and decay of small perturbations around the RT equilibrium, with the density remaining strictly positive. The results provide a rigorous nonlinear counterpart to linear quantum stabilization and offer a robust energy-analytic framework applicable to quantum fluids with RT-type instabilities and Navier boundary conditions.
Abstract
It is well-known that the Rayleigh--Taylor (abbr. RT) instability can be completely inhibited by the quantum effect stabilization in proper circumstances leading to a cutoff wavelength in the \emph{linear} motion equations. Motivated by the linear theory, we further investigate the {stability} for the \emph{nonlinear} RT problem of quantum Navier--Stokes equations in a slab with Navier boundary condition, and rigorously prove the inhibition of RT instability by the quantum effect under a proper setting. More precisely, if the RT density profile $\barρ$ satisfies an additional stabilizing condition, then there is a threshold ${\varepsilon_{c}}$ of the scaled Planck constant, such that if the scaled Planck constant is bigger than ${\varepsilon_{c}}$, the small perturbation solutions around an RT equilibrium state are algebraically stable in time. The mathematical proof is realized by a complicated multi-layer energy method with anisotropic norms of spacial derivatives.
