# F. Dias's research while affiliated with Université Paris-Saclay and other places

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## Publications (26)

We investigate occurrences of anomalous tidal activity in coastal waters of north-west Europe during Summer 2022. Sightings of an anomalous “tidal surge” occurred on 18 June 2022 in Wales, followed by similar observations in Ireland, France, and Spain. Several anomalous long-wave events were also reported in south England and Wales in the morning o...

We model regular and irregular design waves of interest in coastal and ocean engineering, using a Numerical Wave Flume (NWF) based on a Moving Particle Semi-Implicit (MPS) method. A key feature of the model is the implementation of a new scheme for the artificial viscosity, which is original to the Smoothed Particle Hydrodynamics (SPH) method and i...

Steady two-dimensional fluid flow over an obstacle is solved using complex variable methods. We consider the cases of rectangular obstacles, such as large boulders, submerged in a potential flow. These may arise in geophysics, marine and civil engineering. Our models are applicable to initiation of motion that may result in subsequent transport. Th...

Boulders are fractured and excavated by large waves along steep coastlines, contributing to coastal erosion. Intense fluid pressures enter cracks in attached bedrock, inducing bending stresses that may result in hydraulic fracture of a block. We consider the dynamic response of an attached rock beam to loading during wave impact. We verify the comp...

Recent wave tank experiments on a flap-type wave energy converter showed the occurrence of extreme wave loads, corresponding to slamming events in highly energetic seas. In this paper, we analyse pressure-impulse values from available pressure measurements, for a series of experimental slamming tests. Then, we devise a pressure-impulse model of the...

Boulder quarrying by large waves along steep, high-energy coastlines contributes to erosion both by causing inland migration of cliff faces and by vertical lowering of coastal platform surfaces. It also leads to the formation of coastal boulder deposits (CBD) above and inland of the high water mark. We describe mechanisms by which hydraulic fractur...

Boulders are fractured and excavated by large waves along steep coastlines, contributing to coastal erosion. Intense fluid pressures enter cracks in attached bedrock, inducing bending stresses that may result in hydraulic fracture of a block. We consider the dynamic response of an attached rock beam to loading during wave impact. We verify the comp...

The pressure load at a vertical barrier caused by extreme wave run-up is analysed numerically, using the conformal mapping method to solve the two-dimensional free surface Euler equations in a pseudo-spectral model. Previously this problem has been examined in the case of a flat-bottomed geometry. Here, the model is extended to consider a varying b...

We present second-order expressions for the free-surface elevation, velocity potential and pressure resulting from the interaction of surface waves in water of arbitrary depth. When the surface waves have nearly equal frequencies and nearly opposite directions, a second-order pressure can be felt all the way to the sea bottom. There are at least tw...

The field of microfluidics utilizes micron-scale devices to control the flow of fluids. The principal application is the manipulation of very small volumes of fluids on the order of nanoliters to femtoliters that are typically seeded with nanoparticles. Hence the control and sorting of nanoparticles is a primary goal using this technology. There is...

With an increasing emphasis on renewable energy resources, wave power technology is becoming one of the realistic solutions. However, the 2011 tsunami in Japan was a harsh reminder of the ferocity of the ocean. It is known that tsunamis are nearly undetectable in the open ocean but as the wave approaches the shore its energy is compressed, creating...

Recent studies have revealed a long history of large waves around
Ireland, which can be attributed to persistent strong winds in this
area. At the same time, due to the consistently high levels of wave
energy, the West Coast of Ireland has attracted a lot of interest as a
prospective site for deployment of wave energy converters (WECs) farms.
The d...

We consider a flap gate farm, i.e. a series of P arrays, each made of Q neighbouring flap gates, in an open sea of constant depth, forced by monochromatic incident waves. The effect of the gate thickness on the dynamics of the system is taken into account. By means of Green's theorem a system of hypersingular integral equations for the velocity pot...

Using a semi-analytical approach, we show that an articulated system of large damped oscillators in the open ocean can be resonated by incoming waves at multiple frequencies. As an application, energy extraction from the system is modelled when the oscillators are used as flap-type wave energy converters. A new parameter -the absorption efficiency...

The run-up of long, strongly nonlinear waves impinging on a vertical barrier can result in remarkable amplification of the far-field amplitude of incoming waves [1,2]. Such an extreme run-up is the result of an evolution process in which long waves experience strong amplification under the action of nonlinear steepening followed by the formation of...

Oyster® is a surface-piercing flap-type device designed to harvest wave energy in the nearshore environment. Established mathematical theories of wave energy conversion, such as 3D point-absorber and 2D terminator theory, are inadequate to accurately describe the behaviour of Oyster, historically resulting in distorted conclusions regarding the pot...

This paper describes a series of experiments undertaken to investigate the slamming of an Oscillating Wave Surge Converter in extreme sea states. These two-dimensional experiments were undertaken in the Wave Flume at Ecole Centrale Marseille. Images from a high speed camera are used to identify the physics of the slamming process. A single pressure...

A potential flow model is derived for a large flap-type oscillating wave energy converter in the open ocean. Application of Green’s integral theorem in the fluid domain yields a hypersingular integral equation for the jump in potential across the flap. Solution is found via a series expansion in terms of the Chebyshev polynomials of the second kind...

An analytical and a numerical model are applied to study the behaviour of the Os-cillating Wave Surge Converter in a channel, under the assumptions of inviscid fluid and irrotational motion. Due to the mirroring effect of the channel lateral walls, the models also describe the behaviour of an infinite array of converters. Both models are successful...

This paper examines the wave scattering by an infinite array of thin plates in the open ocean, used for the purpose of wave energy extraction. Among the tasks necessary to describe the behaviour of such a system and to optimise its efficiency, the analysis of the scattering of the incident waves by the plates is of particular importance. Within the...

A mathematical model is developed to study the behaviour of an oscillating
wave energy converter in a channel. During recent laboratory tests in a wave
tank, peaks in the hydrodynamic actions on the converter occurred at certain
frequencies of the incident waves. This resonant mechanism is known to be
generated by the transverse sloshing modes of t...

The analytical 3D model of Renzi and Dias (2012) developed to investigate the resonant behaviour of an Oscillating Wave Surge Converter (OWSC) in a channel is used here to study the hydrodynamic loading on an array of devices in random seas. Within the framework of a linear theory, separation of variables and the application of Green's theorem yiel...

This paper presents experimental and numerical studies into the hydrodynamic loading of a bottom-hinged large buoyant flap held rigidly upright in waves. Possible applications and limitations of physical experiments, a linear potential analytical method, a linear potential numerical method, a weakly non-linear tool and RANS CFD simulations are disc...

We quantify through simple population-dynamics models the biological growth on wave energy converters (WECs). We also evaluate the effects of the inherently unsteady flow induced by waves and currents on the settlement of various species. Finally, we discuss the impact of the biological growth on the flow pattern around such devices (and consequent...

## Citations

... Consequently such methods are computationally very expensive, and therefore less popular in the context of modelling MSD-generated waves. For example, in the last few decades, few studies of landslide-generated waves have employed a Lagrangian approach [see15, [19][20][21][22] [23] is the use of a semi-implicit numerical scheme for pressure, based on empirical coefficients that require further tuning. In the present paper, we improve the model of Ref. Renzi and Dias [23] by using an explicit algorithm to solve the pressure field. ...

... get the Schwarz-Christoffel formula for the standard step condition(Herterich, 2020): ...

... Later this model was extended to three dimensions by Deborah and Peregrine (1998), and the case of trapped air was studied by Wood et al. (2000). Subsequently, this approach has been applied in more complicated configurations, including the breaking wave impact on a wall (Lobovský et al. 2014;Lugni et al. 2006), breaking wave impact on a permeable breakwater (Cooker 2013), wave impact on an oscillating wave energy converter (Renzi et al. 2018); and wave impact on a hydraulic structure with an overhang (Chen et al. 2019). Chen et al. (2019) also used impact impulses as the primary design variable to estimate the impulsive reaction force. ...

... Since the filling flow has been studied mostly from an analytical 16,17 and physical 18,19 point of view, the aim of the present research is to analyze the filling flow through laboratory and numerical experiments, in order to validate the model by 1 and to provide a relationship between the incoming wave properties and the filling flow hydraulic parameters. A Plexiglas box was used to resemble the cavity, installed at one side of a rectangular tank and the incoming flow was generated by means of the sloshing flow in a tank horizontally forced by a mechanical system. ...

... The maximum offshore wave height H max can be approximated by 2H s (e.g., Krogstad, 1985;Cattrell et al., 2018), but seas evolve as they transit the shelf and shoal toward land, so that H max obtained from buoy data may not match maximum wave height at the coast. Wave energy attenuates across the continental shelf, typically causing large swell height to decrease by about half (Ardhuin et al., 2003;Janjić et al., 2018), but amplification commonly occurs near shore, as shoaling waves interact with sea bed and coast (Viotti and Dias, 2014;Akrish et al., 2016;Brennan et al., 2017). Predicting coastal wave heights is therefore complicated. ...

... A better understanding of the pressure fields produced by intense surface waves is necessary for more efficient diagnostics of sea conditions, as well as for the improvement of the methods to solve the inverse problem. Approximate analytic solutions for particular surface wave patterns (e.g., long-wave solitons in shallow water; weakly nonlinear cross seas; wave groups in relatively deep water, etc, see Pellet et al, 2017;Slunyaev et al, 2018;Touboul & Pelinovsky, 2018) are useful for better qualitative understanding, and may be used as benchmarks. ...

... The most restrictive assumption is The analytical 3D model developed by Renzi and Dias [16] is used to compute the load on the flap. This is the same model that is implemented to determine the hydrodynamic loading on an array of OWSCs in random seas [21][22][23]. Until now, this model had only been used to compute forces under normal operational conditions for OWSCs, that is waves with periods between 5 s and 20 s. Even though there is no assumption on the wave period in the derivation of the model, special care must be taken when evaluating the solution for long waves. ...

... They showed that a simple, nearly monochromatic wave group can produce a run-up amplitude in excess of six times the far-field amplitude. Viotti et al. [5] extended the model to account for non-flat bathymetry, while Brennan et al. [6] examined the associated pressure fluctuations on the barrier. Akrish et al. [7,8] reproduced the run-up using a higher order spectral (HOS) method, and also looked at the resulting force on the wall. ...

... Over the past two decades, a number of studies are conducted to understand how OSWECs' structures and interactions between ocean waves and flaps affect converters performance. Henry et al.'s experiment on oscillating surge wave energy converters is considered as one of the most influential pieces of research [25], which demonstrated how the performance of oscillating surge wave energy converters (OSWECs) is affected by seven different factors, including wave period, wave power, flap's relative density, water depth, free-board of the flap, the gap between the tubes, gap underneath the flap, and flap width. These parameters were assessed in their two models in order to estimate the absorbed energy from incoming waves [26,27]. ...

... However, opposite conclusions have been drawn by other researchers. Tiron et al. [9] quantified marine growth on WECs using numerical population-dynamic models. Given that the pre-dicted biofouling accounted for approximately 10% of the total mass of the WEC, they concluded that biofouling could have an important effect on its energy-absorption capabilities. ...