We consider numerical approximations of stochastic differential equations by
the Euler method. In the case where the SDE is elliptic or hypoelliptic, we
show a weak backward error analysis result in the sense that the generator
associated with the numerical solution coincides with the solution of a
modified Kolmogorov equation up to high order terms with respect to the
stepsize.
We study the long time behavior of the solution of a stochastic PDEs with
random coefficients assuming that randomness arises in a different independent
scale. We apply the obtained results to 2D- Navier--Stokes equations.
We show that the Cauchy Problem for a randomly forced, periodic
multi-dimensional scalar first-order conservation law with additive or
multiplicative noise is well-posed: it admits a unique solution, characterized
by a kinetic formulation of the problem, which is the limit of the solution of
the stochastic parabolic approximation.
We consider a stochastic partial differential equation with two logarithmic
nonlinearities, with two reflections at 1 and -1 and with a constraint of
conservation of the space average. The equation, driven by the derivative in
space of a space-time white noise, contains a bi-Laplacian in the drift.