arXiv subjects
Publications and source records attributed to Jiri Neustupa.
We prove that if $0 0$, where $\mathcal{F}_γ(s)=s\, [\ln{}(1+ s)]^{1+γ}$ and the subscripts "$-$" and "$+$" denote the negative and the nonnegative part, respectively, then the solution $(\mathbf{u},\mathbf{b},p)$ has no singular points in $\mathbb{R}^3\times(0,T_0]$.
We show that if u is a weak solution to the Navier-Stokes initial-boundary value problem with Navier's slip boundary conditions in $Q_T:=Ω\times(0,T)$, where $Ω$ is a domain in $R^3$, then an associated pressure $p$ exists as a distribution with a certain structure. Furthermore, we also show that if $Ω$ is a "smooth" domain in $R^3$ then the pressure is represented by a function in $Q_T$ with a certain rate of integrability. Finally, we study the regularity of the pressure in sub-domains of $Q_T$, where $u$ satisfies Serrin's integrability conditions.
We formulate a new criterion for regularity of a suitable weak solution v to the Navier-Stokes equations at the space-time point (x_0,t_0). The criterion imposes a Serrin-type integrability condition on v only in a backward neighbourhood of (x_0,t_0), intersected with the exterior of a certain space-time paraboloid with vertex at point (x_0,t_0). We make no special assumptions on the solution in the interior of the paraboloid.
We deal with a weak solution v to the Navier-Stokes initial value problem in R^3 x(0,T). We denote by ω^+ a spectral projection of ω=\curl\, v, defined by means of the spectral resolution of identity associated with the self-adjoint operator \curl. We show that certain conditions imposed on ω^+ or, alternatively, only on ω^+_3 (the third component of ω^+) imply regularity of solution v.