On the persistence of H\"older regular patches of density for the inhomogeneous Navier-Stokes equations

Raphaël Danchin (1) , Xin Zhang (1)

1 LAMA - Laboratoire d'Analyse et de Mathématiques Appliquées

In our recent work dedicated to the Boussinesq equations [Danchin and Zhang 2016], we established the persistence of solutions with piecewise constant temperature along interfaces with H\"older regularity. We here address the same problem for the inhomogeneous Navier-Stokes equations satisfied by a viscous incompressible and inhomogeneous fluid. We establish that, indeed, in the slightly inhomogeneous case, patches of densities with $\mathcal{C}^{1, \varepsilon}$ regularity propagate for all time. As in [Danchin and Zhang 2016], our result follows from the conservation of H\"older regularity along vector fields moving with the flow. The proof of that latter result is based on commutator estimates involving para-vector fields, and multiplier spaces. The overall analysis is more complicated than in [Danchin and Zhang 2016] however, since the coupling between the mass and velocity equations in the inhomogeneous Navier-Stokes equations is \emph{quasilinear} while it is linear for the Boussinesq equations.

Domaines: Equations aux dérivées partielles [math.AP]

Raphaël Danchin, Xin Zhang. On the persistence of H\"older regular patches of density for the inhomogeneous Navier-Stokes equations. 2016. ⟨hal-01406384⟩