Predominantly unidirectional flow of a viscous liquid

Under consideration is the problem of the flow of a viscous liquid in the presence of solid bodies (namely, the two walls and a plate whose boundary is permeable for the liquid) under some influences periodical in time. The formulation of the problem includes the equation of Navier–Stokes, the equation of continuity, and the conditions at the solid boundaries of the liquid. The new hydro-mechanical effect is revealed which consists in the following: in the absence of a predominant direction in space, the free parts of the hydro-mechanical system (i.e., the liquid layers) perform the unidirectional steady motion at a background of oscillations.