The gravity-capillary wind wave facility is located in the Research Hallway of the MHL. Research conducted in this facility includes, but is not limited to, the following areas:

• wind-waves and wind-shear interacting with mechanically generated water waves
• understanding and facilitating fluid control in microgravity environments by utilizing servo-controlled motors with feedback to generate mean motion through longitudinally oscillating horizontal cylinders containing fluid
• investigating contact line dynamics by conducting experiments in uni-directionally rotating and oscillating axially circular cylinders
• the flow physics associated with oscillating thin disks and similarly shaped bodies used in offshore structures (tension-leg platforms and spar buoys)
• utilizing high-speed imaging, particle-image velocimetry, particle-tracking velocimetry, and flow visualization techniques

The gravity-capillary wind wave facility is equipped with experimental tanks and basins and specialized equipment. The largest of the facilities is the air-sea interaction tank.  It is used to study gravity-capillary wind-wave interactions, and to investigate beach profiles and sediment transport phenomena. The basin is 35 meters long, 0.7 meters wide, and can support maximum water depths of approximately 1.2 meters. The air flow is generated by a 40 horsepower suck-down flow loop that is capable of producing air flows between two and 30 meters per second. Additionally, the basin is equipped with a computer controlled wedge-type mechanical wave generator capable of providing feedback and producing maximum frequencies of 10 Hz. The cross-sectional area of the combined water-air flow increases downstream to facilitate the growing boundary layers.

The air-sea interaction tank is used to study steep, high frequency gravity waves and the parasitic capillary waves they generate. Additionally, waves subject to internal resonance phenomena are also under investigation.  These short waves are of fundamental importance involving the contact line at the air-water-ship hull interface and electromagnetic (radar) scattering from rough ocean surfaces.  Remote sensing of the ocean surface reveals features such as ship wakes, ocean current boundaries, pollution slicks, bathymetry, and wind driven wave fields. Since electromagnetic waves are primarily scattered by water waves of approximately the same wavelength, the ability to detect remotely these characteristics depends on the generation and disturbance of the short, high frequency, gravity-capillary waves on the free surface.

Figure. Air-sea interaction tank.

Figure. Air-sea interaction tank with ship model.