Existence and regularity properties of solutions for the evolutionary system describing unsteady flows of incompressible fluids with shear dependent viscosity are studied. The problem is considered in a bounded, smooth domain of $\mathbb R ^3$ with Dirichlet boundary conditions. The nonlinear elliptic operator, which is related to the stress tensor, has $p$ structure. The paper deals with the case $p\ge 2$, for which the existence of weak solutions is proved. If $p\ge \frac{9}{4}$ then a weak solution is strong and unique among all weak solutions.

We study the existence and nonexistence of solutions for a class of equations of the form $-(\omega u')'=|u|^{p-2}u$ in $\mathbb R$ where $p>2$ and $\omega$ is a nonnegative continuous function with isolated zeroes of power type.

We consider equations of the form $${\partial}_{t} v - \mbox{div} ( \alpha (v) \nabla v) = 0 \ , $$ where $v \in [0,1]$ and $\alpha (v)$ degenerates for $v=0$ and $v=1$. We show that local weak solutions are locally Hölder continuous provided $\alpha$ behaves like a power near the two degeneracies. We adopt the technique of intrinsic rescaling developed by DiBenedetto.

Initial and initial-boundary value problems for linearized magneto-thermo-elastic models are considered. For the Cauchy problem in three space dimensions, a polynomial rate of decay as time tends to infinity is proved. In bounded domains a boundary condition of memory type is considered for the displacement. When the relaxation function satisfies dissipative properties and decays exponentially, we show that the solution of the magneto-thermo-elastic system decays exponentially. When the relaxation function decays polynomially, it is proved that the solution decays polynomially. Energy methods are used.