116 research outputs found
Balanced Truncation Model Reduction of a Nonlinear Cable-Mass PDE System with Interior Damping
We consider model order reduction of a nonlinear cable-mass system modeled by
a 1D wave equation with interior damping and dynamic boundary conditions. The
system is driven by a time dependent forcing input to a linear mass-spring
system at one boundary. The goal of the model reduction is to produce a low
order model that produces an accurate approximation to the displacement and
velocity of the mass in the nonlinear mass-spring system at the opposite
boundary. We first prove that the linearized and nonlinear unforced systems are
well-posed and exponentially stable under certain conditions on the damping
parameters, and then consider a balanced truncation method to generate the
reduced order model (ROM) of the nonlinear input-output system. Little is known
about model reduction of nonlinear input-output systems, and so we present
detailed numerical experiments concerning the performance of the nonlinear ROM.
We find that the ROM is accurate for many different combinations of model
parameters
Finite dimensional attractor for a composite system of wave/plate equations with localised damping
The long-term behaviour of solutions to a model for acoustic-structure
interactions is addressed; the system is comprised of coupled semilinear wave
(3D) and plate equations with nonlinear damping and critical sources. The
questions of interest are: existence of a global attractor for the dynamics
generated by this composite system, as well as dimensionality and regularity of
the attractor. A distinct and challenging feature of the problem is the
geometrically restricted dissipation on the wave component of the system. It is
shown that the existence of a global attractor of finite fractal dimension --
established in a previous work by Bucci, Chueshov and Lasiecka (Comm. Pure
Appl. Anal., 2007) only in the presence of full interior acoustic damping --
holds even in the case of localised dissipation. This nontrivial generalization
is inspired by and consistent with the recent advances in the study of wave
equations with nonlinear localised damping.Comment: 40 pages, 1 figure; v2: added references for Section 1, submitte
Eliminating flutter for clamped von Karman plates immersed in subsonic flows
We address the long-time behavior of a non-rotational von Karman plate in an
inviscid potential flow. The model arises in aeroelasticity and models the
interaction between a thin, nonlinear panel and a flow of gas in which it is
immersed [6, 21, 23]. Recent results in [16, 18] show that the plate component
of the dynamics (in the presence of a physical plate nonlinearity) converge to
a global compact attracting set of finite dimension; these results were
obtained in the absence of mechanical damping of any type. Here we show that,
by incorporating mechanical damping the full flow-plate system, full
trajectories---both plate and flow---converge strongly to (the set of)
stationary states. Weak convergence results require "minimal" interior damping,
and strong convergence of the dynamics are shown with sufficiently large
damping. We require the existence of a "good" energy balance equation, which is
only available when the flows are subsonic. Our proof is based on first showing
the convergence properties for regular solutions, which in turn requires
propagation of initial regularity on the infinite horizon. Then, we utilize the
exponential decay of the difference of two plate trajectories to show that full
flow-plate trajectories are uniform-in-time Hadamard continuous. This allows us
to pass convergence properties of smooth initial data to finite energy type
initial data. Physically, our results imply that flutter (a non-static end
behavior) does not occur in subsonic dynamics. While such results were known
for rotational (compact/regular) plate dynamics [14] (and references therein),
the result presented herein is the first such result obtained for
non-regularized---the most physically relevant---models
Flow-plate interactions: Well-posedness and long-time behavior
We consider flow-structure interactions modeled by a modified wave equation
coupled at an interface with equations of nonlinear elasticity. Both subsonic
and supersonic flow velocities are treated with Neumann type flow conditions,
and a novel treatment of the so called Kutta-Joukowsky flow conditions are
given in the subsonic case. The goal of the paper is threefold: (i) to provide
an accurate review of recent results on existence, uniqueness, and stability of
weak solutions, (ii) to present a construction of finite dimensional,
attracting sets corresponding to the structural dynamics and discuss
convergence of trajectories, and (iii) to state several open questions
associated with the topic. This second task is based on a decoupling technique
which reduces the analysis of the full flow-structure system to a PDE system
with delay.Comment: 1 figure. arXiv admin note: text overlap with arXiv:1208.5245,
arXiv:1311.124
General decay of the solution for a viscoelastic wave equation with a time-varying delay term in the internal feedback
In this paper we consider a viscoelastic wave equation with a time-varying
delay term, the coefficient of which is not necessarily positive. By
introducing suitable energy and Lyapunov functionals, under suitable
assumptions, we establish a general energy decay result from which the
exponential and polynomial types of decay are only special cases.Comment: 11 page
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