Tepper L Gill and Woodford W. Zachary
SUFFICIENCY CLASS FOR GLOBAL (IN TIME) SOLUTIONS
TO THE 3D-NAVIER-STOKES EQUATIONS in H
(343K, pdf)
ABSTRACT. Let $ \Om $ be an open domain of class $\mathbb{C}^3 $ contained in ${\mathbb {R}}^3 $, let $({{\mathbb L}^{{2}} [ \Om ])^3 }$ be the real Hilbert space of square integrable functions on ${ \Om} $ with values in ${\mathbb {R}}^3$, and let ${\mathbb H}{\text{[}} \Om {\text{]}}$ be the completion of the set, $\left\{ {{\bf{u}} \in (\mathbb {C}_0^\infty [ \Om ])^3 \left. {} \right|\,\nabla \cdot {\bf{u}} = 0} \right\}$, with respect to the inner product of ${({\mathbb L}^2 [ \Om ])^3} $. A well-known unsolved problem is the construction of a sufficient class of functions in ${\mathbb H}{\text{[}} \Om {\text{]}}$ which will allow global, in time, strong solutions to the three-dimensional Navier-Stokes equations. These equations describe the time evolution of the fluid velocity and pressure of an incompressible viscous homogeneous Newtonian fluid in terms of a given initial velocity and given external body forces. In this paper, we prove that, under appropriate conditions, there exists a number $ {{\bf{u}}_ +} $, depending only on the domain, the viscosity, the body forces and the eigenvalues of the Stokes operator, such that, for all functions in a dense set
$\mathbb{D}$ contained in
the closed ball ${{\mathbb B} ( \Om )}$ of radius
$ {\bf{u}_ +} $ in ${{\mathbb H}[ \Om ]}$, the Navier-Stokes equations have unique, strong, solutions in ${\mathbb C}^{1} \left( {(0,\infty ),{\mathbb H}[ \Om ]} \right)$.