Problem on small motions and normal oscillations of capillary viscous liquids in rotating vessels

The new recent results of the author are applied to study the problem. We begin from the problem posing. Then we consider the problem as a system of operator equations in a Hilbert space. Further, the initial-boundary value problem is reduced to the Cauchy problem for the abstract parabolic equation; this allows us to prove the unique solvability theorem. Then we study normal oscillations of the hydraulic system under the assumption of static stability with respect to the linear approximation. We prove results about the spectrum of the problem and prove that the system of root functions (eigenfunctions and associated functions) form a basis. Also, we prove that if the static stability assumption is not satisfied, then the inversion of Lagrange's theorem on the stability is valid.