The Influence of Gravity on Fluid-Structure Impact

Zekri, H. J. (2016) The Influence of Gravity on Fluid-Structure Impact. Doctoral thesis, University of East Anglia.

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Fluid-structure interaction is a well-known and complicated problem.
Its formulation requires simpli�cations in modelling, and usually
the presence of gravity is one aspect which is neglected, especially
in violent impact. In this thesis we account for the in
of gravity on two physically di�erent but mathematically similar
ows. First (in Chapters 2{4), sloshing impact of
a standing wave on the lid of a rigid tank, and second (in Chapter
5), impact of a rigid blunt body entering water which is initially at
Chapter 1 presents the motivation, literature, aim and structure
of the thesis. In Chapter 2, gravity is neglected and model
equations are solved analytically, in particular the linearised hydrodynamic
problem with and without the lid using the Wagner
approximation, time and coordinate stretching, and displacement
potential. Chapter 3, introduces gravity into the formulation and
the model is solved semi-analytically to determine its in
uence on
the width of the wetted region and on the pressure distribution on
the lid during impact. We numerically �nd the e�ect of gravity
on the moving contact points, hydrodynamic pressure, and surface
elevation in Chapter 4. Chapter 5 studies the in
uence of gravity
on the impact of a blunt body entering vertically with a constant
speed into an initially
at water. All problems are formulated and
solved within the Wagner model.
In both problems we found visible e�ects of gravity on the positions
of moving contact points after the early stage of impact.
Gravity shortens the size of the wetted region. Consequently, the
velocities of the contact points are decreased by gravity. The effect
of gravity on the surface elevation is shown for both problems.
Negative hydrodynamic pressures and forces are found during the
sloshing impact stage when gravity is neglected. Numerically, it was
found that gravity decreases the hydrodynamic pressure on the lid
of the tank. Similarly the hydrodynamic pressure is found to be
decreased by gravity in the water-entry problem. Also in the waterentry
problem it is shown that gravity increases both the thickness
and the mass
ux into the spray jets. Also the total energy (potential
and kinetic) of the system, and th

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Mathematics
Depositing User: Vailele Chittock
Date Deposited: 23 Aug 2016 10:21
Last Modified: 23 Aug 2016 10:21

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