Asymptotical Behavior of Global Solutions of the Navier-Stokes-Korteweg Equations with Respect to Capillarity Number at Infinity
Fei Jiang, Pengfei Li, Jiawei Wang
TL;DR
The paper analyzes the diffuse-interface NSK system in a slab with Navier–slip boundaries and constant viscosity, focusing on the large capillarity regime $\kappa\to\infty$. It proves the global-in-time existence of strong solutions with uniform-in-$\kappa$ energy bounds for small initial perturbations, and shows that, as $\kappa\to\infty$, the 3D NSK dynamics converge to a 2D incompressible NS-like system governing the horizontal velocity, with a precise description of the limit fields. The analysis hinges on refined energy methods, handling a challenging nonlinear term via transport equations and anisotropic estimates, and a compactness framework to pass to the limit. The results reveal a stabilizing elastic-like effect of capillarity and establish a rigorous link between the 3D NSK dynamics and a reduced 2D NS-type model in the high-capillarity regime. These contributions advance understanding of capillarity-driven asymptotics and provide a methodology for extracting reduced-dimensional limits in complex fluid models.
Abstract
Vanishing capillarity in the Navier-Stokes-Korteweg (NSK) equations has been widely investigated, in particular, it is well-known that the NSK equations converge to the Navier-Stokes (NS) equations by vanishing capillarity number. To our best knowledge, this paper first investigates the behavior of large capillary number, denoted by $κ^2$, for the global(-in-time) strong solutions with small initial perturbations of the three-dimensional (3D) NSK equations in a slab domain with Navier(-slip) boundary condition. Under the well-prepared initial data, we can construct a family of global strong solutions of the 3D incompressible NSK equations with respect to $κ>0$, where the solutions converge to a unique solution of 2D incompressible NS-like equations as $κ$ goes to infinity.
