This Work suggests a study of small motions of system of capillary viscous fluids in rotation vessels ,i.e: to prove the unique solvability theorem of the initial boundary value problem that describe these motions. For that we reduced to Cauchy problem that has the form: Where is a continuous function with values in the Hilbert space E, A is an operator on E, By using Functional analysis methods (Orthogonal projector, Operator approach,…)