Angeliki E. Karperaki

• Doctor of Engineering
• Lecturer at Aston University

Understanding the mechanics of aquatic locomotion has been an active field of research for decades and continues to inspire technological solutions ranging from small-scale propulsion systems for autonomous underwater vehicles (AUVs) to larger-scale energy saving devices (ESDs) for ships. The bio-inspired thrust-producing kinematics are shared amon...

The interaction between surface waves, tides and bathymetry play a significant role in governing particle trajectories around reefs. Mixing and chaotic structures formed by these interactions transport and trap particles such as nutrients, sediments and larvae that are essential to maintaining healthy reefs, and microplastics or other contaminants...

In the present work, we focus on noise generation by a flapping foil used for small ship and AUV propulsion and its propagation in the inhomogeneous sea environment. The pressure field and the forces produced by flapping thruster motion, obtained by a BEM model, are used to calculate the dipole and monopole terms associated with the initial-boundar...

Bio-inspired thrusters designed to mimic the propulsive capabilities and mechanisms of fish locomotion pose an alternative to the conventional autonomous underwater vehicle (AUV) propeller propulsion. In this work, we examine a particular configuration of a flapping-foil thruster, employed for AUV propulsion, operating at a constant speed that unde...

In the present work, we focus on noise generation by a flapping foil used for small ship and AUV propulsion and its propagation in the inhomogeneous sea environment. The pressure field and the forces produced by flapping thruster motion, obtained by a BEM model, are used to calculate the dipole and monopole terms associated with the initial-boundar...

A novel frequency domain numerical method for Very Large Floating Structure (VLFS) hydroelasticity is developed. The problem is formulated in the 2D ocean waveguide, featuring a realistic seabed bathymetry and the presence of inhomogeneous, elastic plates of varying thickness and negligible draft. An in vacuo modal expansion for the elastic body de...

For coastal engineering studies and the efficient design of ports and harbors, reliable information concerning wave conditions in nearshore and coastal sites is needed. In the absence of long-term wave data at the site of interest, this becomes possible by using offshore data, which are usually available in the nearby geographical area, in addition...

Recent studies indicate that nature-inspired thrusters based on flexible oscillating foils show enhanced propulsive performance. However, understanding the underlying physics of the fluid-structure interaction (FSI) is essential to improve the efficiency of existing devices and pave the way for novel energy-efficient marine thrusters. In the presen...

The performance of oscillating hydrofoils in the presence of waves and currents is studied for the exploitation of combined renewable marine energy sources in nearshore and coastal regions. These systems operate as semi-activated biomimetic energy device, with imposed pitching motion and induced heaving motion in harmonic incident waves and current...

Water-wave propagation in nearshore regions and hydroacoustic scattering problems, in the presence of structures, are fundamental to ocean and coastal engineering. Efficient modelling of these phenomena can be achieved using the Helmholtz equation with spatially varying coefficients to which mild-slope models are reducible. Despite the relatively s...

Rhythmic hydroelastic oscillations of ice shelves are a key mechanism believed to affect several phenomena observed in Polar Regions, such as the disintegration of ice shelves due to ocean wave impact or even the formation of localised distinctive atmospheric waves. The fundamental and lower hydroelastic modes of an ice-shelf/sub-ice-shelf cavity c...

The hydroelastic response of flexible, floating breakwaters is a subject of interest for coastal engineering applications. In this study, a higher order hydroelastic finite element is applied to the simulation of floating breakwaters of variable stiffness undergoing long wave impact. The main aim is the evaluation of breakwater efficiency in terms...

In order to ensure the safe operation of a VLFS, a combination of mooring, breakwater and other motion reducing systems is employed. In the present work, the transient hydroelastic response of a floating, thin elastic plate, elastically connected to the seabed, is examined. The plate is modelled as an Euler-Bernoulli strip, while the linearized sha...

A higher order finite element scheme is presented for the study of the transient hydroelastic response of a floating, thin, nonlinear strip in shallow wave conditions. First, nonlinear effects are introduced only in the elasticity model, where large deflections and non-negligible normal stress variation in the lateral direction are assumed. The non...

The transient hydroelastic response of an ice shelf under long wave excitation is analysed by means of the finite element method. The simple model, presented in this work, is used for the simulation of the generated kinematic and stress fields in an ice shelf, when the latter interacts with a tsunami wave. The ice shelf, being of large length compa...

The transient hydroelastic response of an ice shelf under long wave excitation is analysed by means of the finite element method. The simple model, presented in this work, is used for the simulation of the generated kinematic and stress fields in an ice shelf, when the latter interacts with a tsunami wave. The ice shelf, being of large length compa...

The hydroelastic response of a thin, nonlinear, elastic strip floating in shalow-water environment is studied by means of a special higher order finite element scheme. Considering non-negligible stress variation in lateral direction, the nonlinear beam model, developed by Gao, is used for the simulation of large flexural displacement. Full hydroela...

A coupled mode model is presented for the propagation of acoustic-gravity waves in layered ocean waveguides. The analysis extends previous work for acoustic waves in inhomogeneous environment. The coupled mode system is derived by means of a variational principle in conjunction with local mode series expansion, obtained by utilizing eigenfunction s...

The study of wave action on large, elastic floating bodies has received considerable attention, finding applications in both geophysics and marine engineering problems. In this context, a higher-order FEM for the numerical simulation of the transient response of thin, floating bodies in shallow-water wave conditions is presented. The hydroelastic i...