Ricerc@Sapienza

We study the behavior on time of weak solutions to the non-stationary motion of an incompressible fluid with shear rate dependent viscosity in bounded domains when the initial velocity $u_0 in L^2$.
Our estimates show the different behavior of the solution as the growth condition of the stress tensor varies. In the "dilatant" or "shear thickening" case we prove that the decay rate does not depend on $u_0$, then our estimates also apply for irregular initial velocity.

We study the weak solvability of a system of coupled Allen--Cahn--like equations resembling cross--diffusion which is arising as a model for the consolidation of saturated porous media. Besides using energy like estimates, we cast the special structure of the system in the framework of the Leray--Schauder fixed point principle and ensure this way the local existence of strong solutions to a regularised version of our system. Furthermore, weak convergence techniques ensure the existence of weak solutions to the original consolidation problem.