5,159 research outputs found
Water-waves modes trapped in a canal by a body with the rough surface
The problem about a body in a three dimensional infinite channel is
considered in the framework of the theory of linear water-waves. The body has a
rough surface characterized by a small parameter while the
distance of the body to the water surface is also of order . Under a
certain symmetry assumption, the accumulation effect for trapped mode
frequencies is established, namely, it is proved that, for any given and
integer , there exists such that the problem has at
least eigenvalues in the interval of the continuous spectrum in the
case . The corresponding eigenfunctions decay
exponentially at infinity, have finite energy, and imply trapped modes.Comment: 25 pages, 8 figure
The localization effect for eigenfunctions of the mixed boundary value problem in a thin cylinder with distorted ends
A simple sufficient condition on curved end of a straight cylinder is found
that provides a localization of the principal eigenfunction of the mixed
boundary value for the Laplace operator with the Dirichlet conditions on the
lateral side. Namely, the eigenfunction concentrates in the vicinity of the
ends and decays exponentially in the interior. Similar effects are observed in
the Dirichlet and Neumann problems, too.Comment: 25 pages, 10 figure
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