General presentation

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Figure 01

The UMS Pytheas Ocean-Atmosphere Interactions laboratory located in Marseille-Luminy campus

Crédit : G. Caulliez

The Ocean-Atmosphere Interaction Laboratory located at the campus of Luminy in Marseille (Figure 1) is equipped of the world-wide known Large Air-Sea Interaction Facility (LASIF) designed for conducting basic and applied researches in the field of air-sea interactions, classical and environmental fluid mechanics as well as wind, oceanic and coastal engineering. This platform is part of the Pytheas Institute (in the joint CNRS-AMU service unit UMS Pytheas) and associated with two research laboratories of Aix-Marseille University : the Mediterranean Institute of Oceanography and the Institut de Recherche sur les Phénomènes Hors Equilibre. The facility is operating since 1972.

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Figure 02

The Large Air-Sea Interaction Facility as seen from outside

Crédit : G. Caulliez

LASIF is a unique infrastructure composed of a 40 m long, 2.6 m wide and 0.9 m deep water tank and a recirculating air flow channel with a 40 m long, 3.2 m wide, 1.5 m high test section (Figure 2). The fan located in the recirculation flume generates winds of velocity up to 14 m/s.

The air flow channel which includes divergent and convergent sections, turbulence grids and a few peculiar features as the slight enlargement of the test section, is specially designed to obtain a low-turbulence homogeneous flow at the entrance of the water tank and a naturally-developing air boundary layer over the water surface (Figure 3).

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Figure 3

Schematic views of the Large Air-Sea Interaction Facility

Crédit : G. Caulliez

Two water pumps can create following or opposite currents up to 10 cm/s in the full water tank. A the end of the water tank, a permeable beach damps the wave reflection. The facility is equipped with large glass windows at 26 m fetch for performing flow and wave visualizations (Figure 4).

A carriage can move the whole instrumentation along the water tank.

A big submerged piston-type wavemaker can generate regular and random water waves (simulation of wind sea spectra) in the frequency range from 0.5 to 2 Hz. It is made of an oscillating plate located at the bottom of a cavity below the air-water flow junction device and controlled by an electro-hydraulic motor driven by a computer. This arrangement enables to generate simultaneously in the water tank mechanical waves and wind flows with a well-controlled turbulent air boundary layer above the oscillating water surface.

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Figure 04

The Large Air-Sea Interaction Facility as seen from the beach at the end of the water tank

Crédit : G. Caulliez