Hydrodynamics, control and numerical modelling of absorbing wavemakers
View/ Open
Maguire.zip (13.03Mb)
Date
22/11/2011Author
Maguire, Andrew Eoghan
Metadata
Abstract
This research investigates the effects that geometry and control have on the
absorption characteristics of active wavemakers and looks at the feasibility of
modelling these wavemakers in commercial computational
fluid dynamic software.
This thesis presents the hydrodynamic coefficients for four different types
of wavemakers. The absorption characteristics of these wavemakers are analysed
using different combinations of control impedance coefficients. The effect of combining
both geometry and control is then investigated. Results, quantifying the
absorption characteristics are then presented. It is shown that the amount of
absorption for a given paddle differs greatly depending on the choice of control
coefficients used to implement complex conjugate control. Increased absorption
can be achieved over a broader bandwidth of frequencies when the geometry of
the wavemaker is optimised for one specific frequency and the control impedance
is optimised for an alternate frequency.
In conjunction to this theoretical study, a numerical investigation is conducted in
order to verify and validate two commercial computational fluid dynamic codes'
suitability to model the previously discussed absorbing wavemakers. ANSYS CFX
and FLOW3D are used to model a physical wavemaker. Both are rigorously verified for discretisation errors and CFX is validated against linear wavemaker theory.
Results show good agreement and prediction of the free surface close to the
oscillating wavemaker, but problems with wave height attenuation and excessive
run times were encountered.
Collections
The following license files are associated with this item: