  Transient Navies--Stokes equations for laminar flow of incompressible fluid
in a channel with permeable wall are reduced to a single equation for the
transversal profile of longitudinal flow velocity. Small--amplitude harmonic
perturbation of injection velocity induces oscillations of longitudinal
velocity with the peak at the walls. The oscillations amplitude in peaks
dramatically increases with the distance along the channel; with the frequency
growth peaks come closer to the walls.
