This article presents an asymptotic analysis of a periodic micropolar fluid flow in an infinite thin channel with an impervious wall and an elastic stratified stiff wall in the context of fluid-structure interaction problems. The considered model was introduced in a previous article (Panasenko et al. in Math. Model. Anal. 29(4):641–668, 2024) and it depends on a small parameter, ${\varepsilon }$ , defined as the ratio between the thickness of the elastic structure and that of the fluid layer. We perform an asymptotic analysis with respect to this small parameter for a suitable scaling of the physical data depending on ${\varepsilon }$ . Corresponding to this choice, the densities are of order ${\varepsilon }^{0}$ , the elasticity coefficients (the Young’s moduli of the stratified elastic structure) are of order ${\varepsilon }^{-3}$ and the external forces acting on the elastic material are of order ${\varepsilon }^{-1}$ . We define an asymptotic solution of order $J$ expressed by means of matrix-valued, vectorial and scalar functions and then we construct and solve the problems for these unknown functions. We provide next a rigorous justification of the asymptotic construction. More precisely, we show that the error between the solution of the physical problem and the asymptotic solution of order $J$ with respect to suitable norms is of order ${\mathcal{O}}({\varepsilon }^{J+\upsilon })$ for any $J \ge 0$ and $\upsilon $ a positive fixed number. This means that the asymptotic solution of order $J$ represents a good approximation of the exact solution even for $J=0$ , that fully justifies our asymptotic construction.
