Local null-controllability of a system coupling Kuramoto-Sivashinsky-KdV and elliptic equations
Kuntal Bhandari, Subrata Majumdar
TL;DR
The paper addresses null-controllability for a mixed KS-KdV-parabolic and elliptic system on $(0,1)$ with a single interior control. It develops global Carleman estimates for the adjoint, leading to observability inequalities and a control cost bounded by $Ce^{C/T}$ for the linearized models. The nonlinear systems are shown to be small-time locally null-controllable using the source-term method and a Banach fixed point argument, both when the control acts in KS-KdV or in the elliptic equation. The results extend KS-type controllability to a parabolic-elliptic coupling and establish a robust framework for single-control strategies in mixed PDE systems with explicit cost estimates.
Abstract
This paper deals with the null-controllability of a system of {\em mixed parabolic-elliptic pdes} at any given time $T>0$. More precisely, we consider the \textit{Kuramoto-Sivashinsky--Korteweg-de Vries equation} coupled with a second order elliptic equation posed in the interval $(0,1)$. We first show that the linearized system is globally null-controllable by means of a localized interior control acting on either the KS-KdV or the elliptic equation. Using the \textit{Carleman approach}, we provide the existence of a control with the explicit cost $Ce^{C/T}$ with some constant $C>0$ independent in $T$. Then, applying the source term method followed by the \textit{Banach fixed point theorem}, we conclude the small-time local null-controllability result of the nonlinear systems.
