Experimental study on the performance of a wave pump for artificial upwelling

When surface gravity waves propagate past a rigid open-ended pipe, there is a negative pressure at the upper end of the pipe. Recently it has been suggested to be used as a wave pump for artificial upwelling. This paper presents experiments and theoretical analysis to obtain the performance of the wave pump in regular waves. Experiments are performed in a wave tank at different density difference heads, wave amplitudes and frequencies with four different pipe diameters. A theoretical model is proposed taking into account the flow characteristics of artificial upwelling. The performance of the model has been confirmed by the experimental findings. The present results show that the pump capacity and efficiency are functions of the wave amplitude and frequency, geometrical parameters of the pipe and vertical distribution of water density. An upwelling flow of 5-360 m3/h can be generated by the wave pump under a wide range of wave conditions. Moreover, the pumped water flow rate and upwelling efficiency can be increased by optimizing the distance between the upper end of the pipe and the trough of the wave, and increasing the pipe diameter. Further work will have to determine the performance of the wave pump in random waves.