The influence of slot injection/suction on the spreading of a thin film under gravity and surface tension

We consider the influence of annular slot injection/suction on the axisymmetric spreading of a thin film where gravity is the driving force. Surface tension effects are included. The singularity due to the no-slip boundary condition is overcome with a precursor film. We show how the width of the slot and magnitude of the injection/suction influences the height of ridges and depth of cavities on the profile of the free surface of the thin film. The presence of surface tension reduces the height of ridges and the depth of cavities that occur when there is no surface tension. We show that slot injection/suction causes the break up of the streamlines.