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arXiv 1111.2464math.AP
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可压缩正压Navier-斯托克斯方程弱解的正则性

Regularity of weak solutions of the compressible barotropic Navier-Stokes equations

Boris Haspot

摘要:

在周期边界条件下,证明了具有常粘性系数的可压缩正压Navier-斯托克斯方程在$N=2,3$维上小时间弱解的正则性和唯一性.本文不要求初始密度有一个正的下界,并假定压力定律满足一个条件,用$γ>1$约化为$P(ρ)=aρ^γ$(在三维中,对$γ$将要求附加尺寸条件)。本文的第二部分是专门的爆破标准略亚临界初始数据的缩放方程时,假设的粘度系数$(μ,λ)$是常数,只要它们的比率是足够大的(特别是$0<λ<(5/4)μ$)。更确切地说,我们证明了在$ρ$属于$L^{\infty}((0,T)\times\T^{N})$的条件下,我们可以将唯一解扩展到$T>0$之外。最后,证明了当$\e>0$任意小时,只要密度在$L^{\infty}(0,T,L^{(N+1+\e)γ}(\mathbb{T}^{N}))$中保持有界,环面$\mathbb{T}^{N}$中的弱解就是光滑的.这一结果可视为可压缩Navier-Stokes方程组的Prodi-Serrin定理(见\cite{prodi}和\cite{serrin})。

英文摘要:

Regularity and uniqueness of weak solutions of the compressible barotropic Navier-Stokes equations with constant viscosity coefficients is proven for small time in dimension $N=2,3$ under periodic boundary conditions. In this paper, the initial density is not required to have a positive lower bound and the pressure law is assumed to satisfy a condition that reduces to $P(ρ)=aρ^γ$ with $γ>1$ (in dimension three, additional conditions of size will be ask on $γ$). The second part of the paper is devoted to blow-up criteria for slightly subcritical initial data for the scaling of the equations when the viscosity coefficients $(μ,λ)$ are assumed constant provided that their ratio is large enough (in particular $0<λ<(5/4)μ$). More precisely we prove that under the condition $ρ$ belongs to $L^{\infty}((0,T)\times\T^{N})$ then we can extend the unique solution beyond $T>0$. Finally, we prove that weak solutions in the torus $\mathbb{T}^{N}$ turn out to be smooth as long as the density remains bounded in $L^{\infty}(0,T,L^{(N+1+\e)γ}(\mathbb{T}^{N}))$ with $\e>0$ arbitrary small. This result may be considered as a Prodi-Serrin theorem (see \cite{prodi} and \cite{serrin}) for compressible Navier-Stokes system.

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