We consider the degenerate problem on low-frequency oscillations of a heavy viscous incompressible fluid in a vessel with free surface of inhomogeneous nonperiodic microstructure. For the obtained quadratic operator pencil we construct the limit (homogenized) pencil which turns out to be degenerate. We prove a homogenization theorem. Bibliography: 40 titles. Illustration: 2 figures.
Dedicated to Nina Nikolaevna UraltsevaA scalar analog of linear hydrodynamics was first described in [1] in detail. Such problems with surfaces of microinhomogeneous periodic structure were considered in [2]-[4], where homogenization of an operator pencil was studied. This study was based on homogenization methods (cf., for example, [5]-[13] and the references therein), asymptotic analysis, and matching asymptotic expansions (cf., for example, [14]). were used. Owing to this approach, it becomes possible to construct effective models of inhomogeneous media or study singular perturbations of problems without microinhomogeneities; moreover, these methods provide rigorous justifications of constructions and accurate proofs. In this direction, various problems with singular perturbation were considered, in particular, perturbation of geometry (cf., for example, [7,12], [15]-[17]), coefficients (cf. [18, 19]), and the type of boundary condition (cf., for example, [20]-[27] and [13]). Similar methods were used in hydrodynamics for studying strongly inhomogeneous fluids with different rheology (cf., for example, [28]-[39]).In this paper, we study a plane analog of the problem on low-frequency oscillations of a heavy viscous incompressible fluid in a vessel with free surface covered by a perforated cap with nonperiodic structure (cf. Figure 1).