Nonequilibrium protection effect and spatial localization of noise-induced fluctuations under gas flow scattering on partially penetrable obstacle

The main problem considered here is how the obstacle embedded in a gas flow can organize self-protection, by means of surrounding gas, against the gas flow and fluctuations. We show that this is possible in the regime of the nonlinear dynamical screening, which is a result of the nonequilibrium transition that is accompanied by the emergence dense gas phase ahead of the obstacle due to blockade effect in a gas, the emergence of local invariants (invariant behavior of obstacle state that becomes insensitive to the main system parameters), spatial localization of induced gas fluctuations near gas domain wall. As a result, the domain wall in a gas, instead of obstacle, becomes the main scatterer of the flow and protects obstacle state against external driving noise and fluctuations. This can be associated with nonequilibrium protection effect. Considered effects are closely related with skin- and edge-correlation ones inherent to non-Hermitian systems. To demonstrate these phenomena, we resort to the limiting case of the two-component lattice gas in a narrow channel with ring geometry. To describe the nonlinear nonequilibrium steady-state gas structures and long-time gas fluctuations near them, the local equilibrium approach and the mean-field approximation are used.