Dossier Océan et énergie - Énergie Thermique des Mers

Sommaire IOA News Letters

HYDRAULIC MODELLING OF WAVE-DRIVEN ARTIFICIAL UPWELLING

by
Clark Liu, University of Hawaii - U.S.A.; and
Elliot Chen, Industrial Technology Research Institute - R.O.C.

Utilization of wave energy to bring up nutrient rich deep ocean water is investigated in this study. Physical and mathematical models have been developed and applied to the development of a wave-driven artificial upwelling device.  The 40 to 1 physical scale model of the device consists of a floating buoy with an inner water chamber, a long tail pipe, and two flow-controlling valves.  Physical modelling experiments were conducted in a wave channel at the University of Hawaii Oceanographic Engineering Laboratory - first to determine values of hydrodynamic parameters of device-wave interaction, and then to evaluate the rate of upwelling flow which the device can produce under design wave conditions. The mathematical model of the device consists of four simultaneous differential equations.  The first three equations, which describe the motion of upwelled water inside the device, were formulated based on momentum and mass conservation principles.  The fourth equation is the equation of motion of the device in ambient waves.  validity of the mathematical model is established by comparing calculated time variations of the water level in the inner water chamber with experimental results.   A verified mathematical model is then used to evaluate effects of device configuration variables on the rate of upwelling flow, and finally to establish design criteria.