Arianna Passerini

Symmetries and constants of motion for constrained Lagrangian systems: a presymplectic version of the Noether theorem

The concept of dynamical symmetry for constrained Lagrangian systems is analysed and generalized. Both the direct and converse Noether theorems are proved for singular Lagrangians.

Existence, uniqueness and stability of steady flows of second and third grade fluids in an unbounded “pipe-like” domain

Abstract We study steady motions of viscous incompressible third-grade fluids in unbounded channels with arbitrary shape. Such flows exist for small fluxes, due to a pressure drop. We prove that they are asymptotically stable in time, provided the viscosity is sufficiently large, and the initial condition on the perturbation sufficiently small.

Generalization of the Lorenz model to the two-dimensional convection of second-grade fluids

Abstract We apply the truncation of the Navier–Stokes–Fourier equations which leads to the Lorenz model, to the investigation of second-grade fluids. The new set of equations proves to work as an approximated approach to 2D-convective dynamics, under the same restrictions as for Newtonian fluids. The different behaviour depends only on α 1 and consists in a “modified” Prandtl number.

STEADY FLOWS OF A VISCOUS INCOMPRESSIBLE FLUID IN A POROUS HALF-SPACE

In this paper we prove the existence and asymptotic behavior of solutions to the equations describing the steady motion of a viscous incompressible fluid in a porous half-space. The results are compared with those already known for the Navier-Stokes model and we find, in particular, that the behavior at large distances is strongly different depending on the value of the incoming flux through the boundary.

Theoretical Results on Steady Convective Flows between Horizontal Coaxial Cylinders

For arbitrary Rayleigh number,

Symmetries in Lagrangian dynamics

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THIRD-GRADE FLUIDS IN THE APERTURE DOMAIN

, Prandtl number, and any ratio of the cylindrical radii, existence of steady solutions of the two-dimensional Oberbeck–Boussinesq system is proved in Theorem 3.5. We show nonlinear stability for large values of the aspect ratio and

Dynamical symmetries in constrained systems: a Lagrangian analysis

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Lagrangian constraints and gauge symmetries

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Comment on `Exploring a rheonomic system'

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