Air-sea momentum transfer in high wind conditions: laboratory experiments.

1
Air-sea momentum transfer in high wind
conditions laboratory experiments.
Ivan Savelyev
Sponsored by
Advisors Brian Haus and Mark Donelan
2
Experiment Setup
Air-Sea Interactions Salt-Water Tank at RSMAS,
University of Miami. Dimensions 15x1x1
meters, Maximum wind speed U30 m/s, Fully
programmable wave-maker with wave height up to H
10 cm.
3
Experiment 1 Wind-wave momentum transfer
4
Background
Early theoretical works
Jeffreys, H., 1924 Miles, J. W., 1957 Airflow separation, sheltering hypothesis. Analytical solution for wind-wave generation.
Experimental efforts
Snyder et al. 1981, Hsiao et al. 1983, Donelan 1999, Donelan et al. 2006, Laboratory and field observations of wave induced static pressure fluctuations.
5
Wave-follower experimental setup.
6
Wave-follower in motion
7
Digital Laser Elevation Gauge (DLEG)
8
DLEG image of the air-sea interface at
9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
Figure 2 from On the limiting aerodynamic
roughness of the ocean in very strong winds,
Donelan et al., 2004.
14
Experiment 2 Wind current kinetic energy
transfer and dissipation.
15
(No Transcript)
16
?
17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
Summary and future work
1) The new high precision wave-follower system
was developed and proved to be successful. 2)
First wave-follower based static pressure
measurements show that wave growth function
keeps growing quadratically as wind forcing
enters hurricane-like conditions. 3) Both
dimensional and non-dimensional approaches are
necessary to resolve form drag contribution to a
total drag in high-wind conditions. 4) In the
future experiments will be studied as a
function of wind speed, wind forcing and wave
steepness. 5) Static pressure dependence on
height and wave phase will be investigated. 5)
Mean current, turbulent kinetic energy, stress
and dissipation rate profiles were measured. 6)
Surface elevation shape is measured
simultaneously with the profiles. Waves role in
wind-current momentum transfer will be
investigated.