Asymptotic log-Harnack inequality for the stochastic convective Brinkman-Forchheimer equations with degenerate noise

Abstract: In this work, we consider the two and three dimensional stochastic convective Brinkman-Forchheimer (SCBF) equations and examine some asymptotic behaviors of its strong solution. We establish the asymptotic log-Harnack inequality for the transition semigroup associated with the SCBF equations driven by additive as well as multiplicative degenerate noise via the asymptotic coupling method. As applications of the asymptotic log-Harnack inequality, we derive the gradient estimate, asymptotic irreducibility, asymptotic strong Feller property, asymptotic heat kernel estimate and ergodicity. Whenever the absorption exponent $r\in(3,\infty)$, the asymptotic log-Harnack inequality is obtained without any restriction on the Brinkman coefficient (effective viscosity) $\mu>0$, the Darcy coefficient $\alpha>0$ and the Forchheimer coefficient $\beta>0$.