We have investigated experimentally the spatiotemporal behavior of a narrow water stream flowing between two parallel inclined Plexiglass plates bounded laterally by air. Complex broadband dynamics occurs as a result of the velocity dependence of the contact angle at the water-air-Plexiglass contact line, which introduces critical values into the pressure required for contact line motion over the Plexiglass plates. This mechanism causes a stick-slip type of motion similar to that appearing in other systems such as flows in granular materials, models of earthquake dynamics, and charge-density-wave motion in solids. We find that above a certain flow rate Qs, a stationary spatial modulation of the width of the stream appears. At higher flow rates, a hysteretic transition occurs in which the contact line begins to move, and the pattern slips down the plates with broadband dynamics. The statistical properties of the motion are presented.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics