Multiscale Analysis of Vibrations of Streamers
L. Demkowicz
Institute for Computational Engineering and Sciences
University of Texas at Austin
(Joint work with S. Prudhomme, W. Rachowicz, W. Qiu and L. Chamoin)
I will discuss an industrial project aimed at simulations and analysis
of streamers. Streamers are six kilometers long tubes, a couple of
inches
in diameter, consisting of structural elements (ropes, spacers and
skin),
filled with gel and packed with microphones. An array of 6-12
streamers,
pulled with a tugboat, is used to record acoustical waves reflected
from
multiple layers in the ocean floor. Through the solution of an inverse
problem, the recorded data is then used to construct geological maps of
the
ocean floor formations. The recorded signals, unfortunately, are
polluted
with a noise produced by the tugboat engine and other sources.
The presented project aims at modeling, simulations and analysis of
the unwanted vibrations of streamers. I will describe various
1D, 2D and 3D finite element models, including highly accurate
hp-adaptive finite elements that we have used in the course of this
project. The problem displays a two-scale behavior, large wave-length
vibrations of the streamer are superimposed with small wave-length
pressure fluctuations. I will present a two-scale analysis that
we have invented to practically solve the problem.