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Ken Abe

Publications and source records attributed to Ken Abe.

26 records · Page 2Linked to original sources

Vanishing viscosity limits for axisymmetric flows with boundary

We construct global weak solutions of the Euler equations in an infinite cylinder $Π=\{x\in \mathbb{R}^{3}\ |\ x_h=(x_1,x_2),\ r=|x_h|<1\}$ for axisymmetric initial data without swirl when initial vorticity $ω_{0}=ω^θ_{0}e_θ$ satisfies $ω^θ_{0}/r\in L^{q}$ for $q\in [3/2,3)$. The solutions constructed are Hölder continuous for spatial variables in $\overlineΠ$ if in addition that $ω^θ_{0}/r\in L^{s}$ for $s\in (3,\infty)$ and unique if $s=\infty$. The proof is by a vanishing viscosity method. We show that the Navier-Stokes equations subject to the Neumann boundary condition is globally well-posed for axisymmetric data without swirl in $L^{p}$ for all $p\in [3,\infty)$. It is also shown that the energy dissipation tends to zero if $ω^θ_{0}/r\in L^{q}$ for $q\in [3/2,2]$, and Navier-Stokes flows converge to Euler flow in $L^{2}$ locally uniformly for $t\in [0,\infty)$ if additionally $ω^θ_{0}/r\in L^{\infty}$. The $L^{2}$-convergence in particular implies the energy equality for weak solutions.

math.AP↗

Liouville theorems for the Stokes equations with applications to large time estimates

We study Liouville theorems for the non-stationary Stokes equations in exterior domains in $ \mathbb{R}^{n}$ under decay conditions for spatial variables. As applications, we prove that the Stokes semigroup is a bounded analytic semigroup on $L^{ \infty}_{ σ}$ of angle $ π/2$ for $n \geq 3$. We also prove large time estimates for $n=2$ with zero net force.

math.AP↗

Axisymmetric flows in the exterior of a cylinder

We study an initial-boundary value problem of the three-dimensional Navier-Stokes equations in the exterior of a cylinder $Π=\{x=(x_{h}, x_3)\ |\ |x_{h} |>1\}$, subject to the slip boundary condition. We construct unique global solutions for axisymmetric initial data $u_0\in L^{3}\cap L^{2}(Π)$ satisfying the decay condition of the swirl component $ru^θ_{0}\in L^{\infty}(Π)$.

math.AP↗

Exterior Navier-Stokes flows for bounded data

We prove unique existence of mild solutions on $L^{\infty}_σ$ for the Navier-Stokes equations in an exterior domain in $ \mathbb{R}^{n}$, $n\geq 2$, subject to the non-slip boundary condition.

math.AP↗

On estimates for the Stokes flow in a space of bounded functions

In this paper, we study regularizing effects of the composition operator $S(t)\mathbb{P}\partial$ for the Stokes semigroup $S(t)$ and the Helmholtz projection $\mathbb{P}$ in a space of bounded functions. We establish new a priori $L^{\infty}$-estimates of the operator $S(t)\mathbb{P}\partial$ for a certain class of domains including bounded and exterior domains. They imply unique existence of mild solutions of the Navier-Stokes equations in a space of bounded functions.

math.AP↗

Stokes Resolvent Estimates in Spaces of Bounded Functions

The Stokes equation on a domain $Ω\subset R^n$ is well understood in the $L^p$-setting for a large class of domains including bounded and exterior domains with smooth boundaries provided $1<p<\infty$. The situation is very different for the case $p=\infty$ since in this case the Helmholtz projection does not act as a bounded operator anymore. Nevertheless it was recently proved by the first and the second author of this paper by a contradiction argument that the Stokes operator generates an analytic semigroup on spaces of bounded functions for a large class of domains. This paper presents a new approach as well as new a priori $L^\infty$-type estimates to the Stokes equation. They imply in particular that the Stokes operator generates a $C_0$-analytic semigroup of angle $π/2$ on $C_{0,σ}(Ω)$, or a non-$C_0$-analytic semigroup on $L^\infty_σ(Ω)$ for a large class of domains. The approach presented is inspired by the so called Masuda-Stewart technique for elliptic operators. It is shown furthermore that the method presented applies also to different type of boundary conditions as, e.g., Robin boundary conditions.

math.AP↗