Non-existence of classical solutions to a two-phase flow model with vacuum
Hai-Liang Li, Yuexun Wang, Yue Zhang
TL;DR
This work demonstrates that classical solutions in the inhomogeneous Sobolev setting cannot persist for the 1D pressureless Euler–Navier–Stokes two-phase flow with vacuum, under suitable initial data near vacuum. By transforming to Lagrangian coordinates and analyzing a degenerate parabolic momentum operator via Hopf's lemma and the strong maximum principle, the authors derive a contradiction that rules out $C^1([0,T];H^m)$ solutions for any $T>0$. The results hinge on the geometric arrangement of the initial densities' supports and sign conditions on the initial velocities, providing two complementary nonexistence regimes. The techniques rely on maximum-principle arguments for degenerate operators and extend to related coupled fluid models, clarifying ill-posedness in inhomogeneous Sobolev spaces for multi-phase flows with vacuum.
Abstract
In this paper, we study the well-posedness of classical solutions to a two-phase flow model consisting of the pressureless Euler equations coupled with the isentropic compressible Navier-Stokes equations via a drag forcing term. We consider the case that the fluid densities may contain a vacuum, and the viscosities are density-dependent functions. Under suitable assumptions on the initial data, we show that the finite-energy (i.e., in the inhomogeneous Sobolev space) classical solutions to the Cauchy problem of this coupled system do not exist for any small time.
