The stochastically forced vorticity equation associated with the two-dimensional incompressible Navier–Stokes equation on Dδ:=[0,2πδ]×[0,2π]Dδ:=[0,2πδ]×[0,2π] is considered for δ≈1δ≈1, periodic boundary conditions, and viscosity 0<ν≪10<ν≪1. An explicit family of quasi-stationary states of the deterministic vorticity equation is known to play an important role in the long-time evolution of solutions both in the presence of and without noise. Recent results show the parameter δδ plays a central role in selecting which of the quasi-stationary states is most important. In this paper, we aim to develop a finite-dimensional model that captures this selection mechanism for the stochastic vorticity equation. This is done by projecting the vorticity equation in Fourier space onto a center manifold corresponding to the lowest eight Fourier modes. Through Monte Carlo simulation, the vorticity equation and the model are shown to be in agreement regarding key aspects of the long-time dynamics. Following this comparison, perturbation analysis is performed on the model via averaging and homogenization techniques to determine the leading order dynamics for statistics of interest for δ≈1δ≈1.
- Bar and dipole states
- Stochastically forced Navier–Stokes
ASJC Scopus subject areas
- Modelling and Simulation
- Applied Mathematics