Flow noise reduction from superhydrophobic surfaces

This work investigates how a highly (super)hydrophobic
surface can be used to reduce turbulence-generated drag and
noise on a towed streamer cable. The work is done by analyzing
full-scale drag and flow noise measurements taken on
a commercial seismic streamer in combination with direct
numerical simulations of turbulence-generated flow noise.
The main findings are that viscous drag and flow noise
can be significantly reduced on a seismic streamer that is
coated to make the surface highly hydrophobic. In an ocean
towing test, a 4% reduction of drag on a streamer section
was measured. In a separate test on a commercial seismic
vessel, a reduction in the flow noise level of nearly 50%
(6 dB) for frequencies below 10 Hz was found. Based upon
an analysis of numerical simulation data, it is suggested that
the reduction in drag and noise can be attributed to a reduced
level of shear stress and change in the kinematic structure of
the turbulence, both of which occur in the immediate vicinity
of the highly hydrophobic surface.