Asymptotic analysis of a perturbed parabolic problem in a thick junction of type 3:2:2

We consider a perturbed initial/boundary-value problem for the heat equation in a thick multi-structure $\Omega_{\varepsilon}$ which is the union of a domain $\Omega_0$ and a large number $N$ of $\varepsilon-$periodically situated thin rings with variable thickness of order $\varepsilon = \mathcal{O}(N^{-1}).$ The following boundary condition $\partial_{\nu}u_{\varepsilon} + \varepsilon^{\alpha} k_0 u_{\varepsilon}= \varepsilon^{\beta} g_{\varepsilon}$ is given on the lateral boundaries of the thin rings; here the parameters $\alpha$ and $\beta$ are greater than or equal $1.$ The asymptotic analysis of this problem for different values of the parameters $\alpha$ and $\beta$ is made as $\varepsilon\to0.$ The leading terms of the asymptotic expansion for the solution are constructed, the corresponding estimates in the Sobolev space $L^2(0,T; H^1(\Omega_{\varepsilon}))$ are obtained and the convergence theorem is proved with minimal conditions for the right-hand sides.