1 Institute of Sensors, Signals and Electrotechnics, Faculty of Engineering, SDU2 Faculty of Engineering, SDU3 Institute of Technology and Innovation, Faculty of Engineering, SDU4 The Maersk Mc-Kinney Moller Institute, Faculty of Engineering, SDU5 Institute of Technology and Innovation, Faculty of Engineering, SDU6 The Maersk Mc-Kinney Moller Institute, Faculty of Engineering, SDU
It has been reported that it is possible to pump a liquid into the interior of a vertical pipe when its lower end is facing a vibrating plane surface immersed in the liquid. The column of liquid pumped in a thin pipe can be higher than 2 m if the gap between the pipe end and the vibrating horizontal surface is very small, around 0.01 mm. In this paper we present experimental results showing that, with a similar set up as the one mentioned above, it is also possible to pump liquids in the opposite direction, from the interior of the pipe through the gap. The general objective of the work has been to advance in the understanding of both phenomena. By using the Boundary Element Method, the sound pressure field in the liquid is determined. The velocity field, Lagrangian excess pressure, and sound intensity are obtained from the sound pressure. Experimental results show that the amplitude of the oscillations of the vibrating horizontal surface determine the direction in which the liquid is pumped. In addition, the size of the gap is also a relevant factor, which has to be significantly small. The carried out numerical simulations show that the Lagrangian excess pressure and the density of linear momentum qualitatively agrees with the movement of the water to the interior of the vertical pipe.