Frédérique LARRARTE

Chercheure Associée LHSV (90%)

Université Gustave Eiffel / Laboratoire d'Hydraulique Saint-Venant

Champs d'intérets

mécanique des fluides , transport solide, expérimentations, instrumentation, domaine maritime

Supervision

Elisa Béteille

Education

2006 Habilitation à Diriger des Recherches, Université de Caen – Basse Normandie,
1994 Doctorat en Dynamique des Fluides et des Transferts de l'Université de Nantes et de l'Ecole Centrale de Nantes
1990 Diplôme d'Etudes Approfondies (D.E.A.) en hydrodynamique navale de l'Ecole Nationale Supérieure de Mécanique de Nantes.
1990 Diplôme de spécialisation de la Section Spéciale d'Hydrodynamique Navale Avancée de l'ENSM (devenue ECN) de Nantes.

Thèse

Frédérique Larrarte. Etude expérimentale et théorique des profils de vagues le long d'une carène.. Sciences de l'ingénieur [physics]. Ecole centrale de Nantes; Université de Nantes, 1994. Français. ⟨NNT : ⟩. ⟨tel-04327370⟩

Publications

Évaluation de l'influence de la sollicitation par chocs de piles circulaires en site aquatique
- Simon Nicolas
- Larrarte Frédérique
- Chevalier Christophe
- Schmidt Franziska
- Carmigniani R.
, 2026 . <div><p>L'affouillement, phénomène d'érosion des sols entraînant des creusements, peut impacter les appuis des ponts, les ducs d'Albe, les conditions d'implantation des éoliennes, ... Cela entraine des modifications de conditions aux limites et modifie également les propriétés vibratoires de la structure considérée. Ainsi, une connaissance fine de la relation entre l'affouillement et l'évolution des propriétés vibratoires de la structure pourrait permettre de développer des systèmes d'instrumentations déployables aisément et à bas coût pour la surveillance des structures soumises à cet aléa. Or l'évaluation des modes propres nécessite une sollicitation de la structure. Afin de mieux comprendre ces phénomènes, un modèle réduit de pile circulaire a été réalisé et une fiabilisation de la méthode de sollicitation par chocs est proposée.</p></div>
Évaluation et fiabilisation de méthodes de sollicitations de modèle réduit de structure application à la détection d'affouillement autour de pile de pont
- Simon Nicolas
- Larrarte Frédérique
- Chevalier Christophe
- Schmidt Franziska
, 2026 . Les propriétés vibratoires d'une structure dépendent notamment des conditions aux limites. L'affouillement, phénomène d'érosion des sols se produisant notamment aux pieds des piles de ponts en site aquatique, se traduit par une modification de ces conditions en induisant un décalage des fréquences propres. Pour étudier ce phénomène, un modèle réduit en laboratoire a été réalisé. L'étude des propriétés vibratoires d'une structure nécessite l'excitation de celle-ci. Dans cette étude, des méthodes de sollicitation par bruit ambiant, shaker et chocs ont été utilisées sur un modèle réduit de pile de pont instrumenté par un accéléromètre triaxial. Un des enjeux repose sur la fiabilisation de la sollicitation et donc du marteau. Un état de l'art portant sur les méthodes de sollicitations puis une évaluation de ces méthodes appliquées à un modèle réduit de pile de pont est mis en place. Finalement, une fiabilisation de la méthode de sollicitation par impact est réalisée.
Impact of Bed Roughness and Submergence on Velocity Profiles and Flow Structures in Hydraulic Jumps
- Agrawal Nishank
- Padhi Ellora
- Larrarte Frédérique
- Singhal Gopal Das
Scientific Reports, Nature Publishing Group , 2026, 16 (1), pp.11676 . Hydraulic jumps downstream of spillways exhibit high near-bed velocities that can induce cavitation and scour. While bed roughness is known to modify velocity distribution and roller characteristics, the underlying flow physics governing velocity transition, turbulence dissipation, and vortex evolution under varying submergence conditions remain insufficiently understood.<p>This study presents an integrated experimental and numerical investigation of free and submerged hydraulic jumps over smooth and corrugated beds to elucidate these mechanisms. Experiments were conducted at discharges of 11, 13, and 15 l s⁻ ¹ for submergence ratios ranging from 0 to 0.4, and complemented by three-dimensional CFD simulations using a RANS-based RNG k-ε model in FLOW-3D. Detailed analyses of velocity similarity profiles, boundary layer development, turbulent kinetic energy (TKE), dissipation rate, total energy loss, and Q-criterion based vortex structures were performed. The results reveal that bed corrugation accelerates boundary layer development, enhances turbulence breakdown, and increases energy dissipation compared to smooth beds. Submergence shifts the turbulence generation zone downstream and increases roller length; however, corrugated beds consistently confine coherent vortices and reduce near-bed velocity under all tested conditions. The study provides new physical insight into turbulence-roughness-submergence interactions in spillway-induced hydraulic jumps and offers design guidance for improving stilling basin performance and reducing downstream scour risk. (10.1038/s41598-026-44480-x)
DOI : 10.1038/s41598-026-44480-x
Mesure de l'érosion des sables : quand le numérique et l'expérimental se complètent pour developper un erodimètre
- Nicolas Xavier
- Larrarte Frédérique
- Merzoud Massinissa
- Michard Clément
- Chevalier Christophe
LHB Hydroscience Journal, Taylor & Francis Group , 2026, 112 (1), pp.2673991 . Un prototype d'érodimètre de terrain, léger et « low cost », a été développé. Nommé PumpET pour Pump Erosion Test, il est dédié à la mesure de l'érodabilité de sédiments fins déposés dans le lit des rivières. Le principe de cet appareil consiste à imposer, à l'aide d'une pompe, des paliers croissants et contrôlés de débits d'eau dans la chambre de mesure, de forme convergente, mise en contact avec le lit de la rivière. La localisation des seuils d'arrachement particulaire est détectée par traitement d'image de vidéos qui filment la chambre. En parallèle, des simulations numériques des écoulements dans la chambre permettent de remonter à la contrainte de cisaillement imposée au niveau du seuil d'arrachement. Nous présentons la démarche expérimentale qui a permis le développement PumpET. Nous détaillons ensuite l'étude numérique RANS-RSM des écoulements dans la rivière et dans le PumpET. Ces simulations montrent que le PumpET génère un champ de contrainte de cisaillement adéquat dans toute la chambre de mesure, pour une large gamme de rapports d'amplitude et de déviation angulaires entre les vitesses d'écoulements dans la rivière et dans la chambre. Cette étude permet aussi de dégager des perspectives d'amélioration du PumpET. (10.1080/27678490.2026.2673991)
DOI : 10.1080/27678490.2026.2673991
Mesure de l'érosion des sables : quand le numérique et l'expérimental se complètent
- Larrarte Frédérique
- Nicolas Xavier
- Merzoud Massinissa
- Michard Clément
- Gomit Guillaume
- Cadet Simon
- Jarny Sébastien
- Chevalier Christophe
, 2025 .
Force - frequency relationship in front crawl swimming
- Brunel Thomas
- Clanet Christophe
- Larrarte Frédérique
- Cohen Caroline
- Carmigniani Rémi
, 2025 . Force - frequency relationship in front crawl swimming
Hydraulic jump analysis: Influence of negative steps and end sills on jump profile for both smooth and Dunal corrugated beds
- Agrawal Nishank
- Padhi Ellora
- Singhal Gopal Das
- Larrarte Frédérique
Physics of Fluids, American Institute of Physics , 2025, 37 (8) . Hydraulic jumps are the key mechanism for energy dissipation downstream o spillways; nevertheless, the intense near-bed velocities they generate can contribute to structural wear and significant scouring downstream of stilling basins. Prior studies have examined the effects of bed roughness, negative steps, and end sills individually; their combined impact remains inadequately explored. This study numerically investigates six stilling basin configurations downstream of an ogee spillway, involving different combinations of smooth and dunal corrugated beds with and without negative steps and end sills. Numerical simulations were performed using FLOW-3D for a discharge of 15 L s−1. To validate the numerical model, experimental data were collected for a dunal corrugated bed configuration, showing strong agreement with simulation results. The analysis included longitudinal velocity profiles, streamline plots, water surface elevations, total energy lines, turbulent kinetic energy, turbulence dissipation, Q-criterion vortex dynamics, etc. The results reveal that a negative step significantly reduces near-bed and depth-averaged velocities, enhancing energy dissipation. The addition of the end sill further promotes flow stability. Among all configurations, the combination of a dunal corrugated bed with a negative step (Model 4) demonstrated the highest energy dissipation and the lowest water surface elevation. Roller length was shortest for the corrugated bed and longest for the smooth bed; however, adding a negative step and end sill increased roller length while improving turbulence control. Q-criterion analysis highlights dense, coherent vortex structures in Model 4, indicating efficient turbulence mixing and energy loss. These results underscore the value of integrating bed roughness with geometric modifications. (10.1063/5.0284062)
DOI : 10.1063/5.0284062
Dam-break flow over various obstacles configurations
- Beteille Elisa
- Larrarte Frederique
- Boyaval Sebastien
- Demay Eric
- Le Minh-Hoang
Journal of Hydraulic Research, Taylor & Francis , 2025, 63, pp.156-170 . Fast floods resulting from the failure of hydraulic structures can be characterized by ‘dam-break’ type waves. They pose catastrophic risks to downstream populations and result in severe structural damage, especially in urban areas. To assess and mitigate these risks, it is essential to forecast the influence of urban forms on flooding severity at a global scale. This paper provides datasets from reduced-scale physical experiments of transient flow through various obstacles configurations. The experiments are conducted in a rectangular horizontal open channel, where flow conditions are achieved by rapidly opening a gate holding a volume of water. To assess the impact of obstacle configurations on flow behaviour, two obstacle sizes are investigated, along with one idealized city layout. The experiments provide complete water hydrographs upstream and downstream of the gate. Additionally, the good performance of the code_saturne computational fluid dynamics (CFD) solver and the volume-of-fluid (VOF) method in numerically simulating the experiments is demonstrated. (10.1080/00221686.2025.2460020)
DOI : 10.1080/00221686.2025.2460020
Où on reparle du pump erosion test pour préciser ses spécificités
- Cadet Simon
- Larrarte Frédérique
- Mbolamana Jules Tinot
- Gomit Guillaume
- Jarny Sébastien
- Nicolas Xavier
- Chevalier Christophe
, 2024 . Un prototype de terrain dédié à la mesure de l'érodabilité de sédiments fins a été développé. Cet appareil, nommé PumpET, pour Pump Erosion Test, a été conçu de manière empirique pour être un matériel de terrain « low cost », aisément transportable et reproductible. Il a été présenté lors des 18èmes Journées de l'Hydrodynamique. Des tests sur le terrain ont permis de valider le concept. Dans le même temps, diverses pistes d'amélioration ont été envisagées. Mais avant toute modification du prototype, nous avons choisi de préciser ses potentialités par, d'une part, des essais en conditions contrôlées et, d'autre part, des simulations numériques impliquant des étudiants de Master 2. Nous présenterons les démarches suivies, les résultats et surtout les implications vers des modifications plus ou moins substantielles de ce prototype.
Experimental analysis on the influence of urban forms on unsteady urban flooding
- Beteille Elisa
- Boyaval Sébastien
- Larrarte Frédérique
- Demay Eric
, 2025 . Unsteady urban flooding, such as dam-break waves, poses catastrophic risks to downstream populations and results in severe damage. To assess and mitigate these risks, it is essential to forecast the influence of urban forms on flooding severity. In this paper, datasets are provided from reduced-scale physical experiments of transient flow through idealized suburban districts. The experiments are conducted in a rectangular horizontal open channel, where flow conditions are achieved by rapidly opening a gate holding a volume of water. To evaluate the impact of urban forms on flow behavior, we investigated two urban parameters; the number and width of streets in the main direction of the flow. The experiments provide complete water hydrographs for thirteen urban forms. Conductive and acoustic gauges are positioned at different locations to track the wavefront and water depth variation. The results illustrate the impact of the two studied urban parameters on flow variables and provide valuable validation data for computational urban planning models.
Un exemple de partage de l’espace : les loisirs nautiques sur la Loire
- Larrarte Frédérique
- Kerhervé Yvon
- Toutain Nicolas
- Jan Hubert
, 2024 . Plus long fleuve de France, la Loire acquiert, à Nantes, un caractère maritime qui a forgé une bonne partie de son histoire et de son développement économique depuis des siècles. Avec un trafic de 30 millions de tonnes de trafic par an, Nantes Saint-Nazaire Port est le 4e grand port maritime français et 28 500 emplois sont générés par l'activité portuaire (selon une étude Insee 2022 sur données 2018). Au-delà de cet aspect économique, la Loire peut être représentée comme l’épine dorsale de l’agglomération nantaise dont les 24 communes se répartissent sur ses 2 rives. Bien connue en termes de génie civil pour ses ouvrages d’art comme le pont de Cheviré ou des éléments du patrimoine maritime comme le canal maritime de la Basse Loire (dit canal de la Martinière), l’agglomération est aussi le lieu de vie de plus de 650000 habitants. Et leurs loisirs regardent souvent vers l’eau ! Dans cette communication, nous présenterons comment les associations sportives se sont structurées en un Collectif des Association Nautiques de l’agglomération nantaise pour permettre que la navigation de loisir, quasi absente sur la Loire il y a 30 ans, reprenne sa place, au même titre que les autres activités, sur la Loire et son affluent l’Erdre, en permettant aux habitants de découvrir leur ville à partir de l’eau, en mode déplacement doux. (10.5150/jngcgc.2024.077)
DOI : 10.5150/jngcgc.2024.077
Les espaces bleus de Nantes Métropole : quand les loisirs nautiques retrouvent la Loire.
- Larrarte Frédérique
- Kerhervé Yvon
- Toutain Nicolas
- Jan Hubert
, 2024 . Beaudelaire disait « Homme libre toujours tu chériras la mer », Renaud chante quant à lui « C’est pas l’homme qui prend la mer, c’est la mer qui prend l’homme ». Et comment, dans la ville natale de Jules Verne qui , rappelons le, a aussi bien écrit l’Ile à Hélice que 20000 lieues sous les mers, ignorer tout l’imaginaire lié à la mer. Le dossier de presse de l’exposition Objectif mer, : l’océan filmé (Musée National de la Marine, Paris, décembre 2023-mai 2024) indique d’ailleurs que « Aujourd’hui, peut-être avec plus de puissance qu’auparavant - effets spéciaux numériques oblige -, la mer est toujours au cinéma ….. Elle symbolise aussi la liberté, le départ vers l’inconnu et les aventures, de même que la fragilité de la Nature et du genre humain, tout en apparaissant impitoyable dans sa masse aveugle et sauvage. ». Ces propos font écho à ceux de Kalaora (Kalaora et Lacroix, 2022) qui dit que « cet espace ouvre vers une part d’aventure et d’incertain parce qu’il incite à larguer les amarres, et à accepter le flottement de la consciences et l’imprévisibilité de la destination finale ». Akoun (1999), cité par Brulé-Josso (2012), indique que « Depuis plus de cent cinquante ans, en mer, l’enthousiasme propre au « mythe » de la « modernité » est exprimé avec force et constance par les amateurs de voile se sentant « libres » de parcourir « les derniers espaces de liberté ». D’après Guigueno ( 2007), « la Coupe de l’America fait partie des spectacles proposés dans un port qui est aussi l’archétype de la métropole moderne ». Mais par ailleurs « La voile sportive n’est pas une pratique populaire. ». Mais toute la voile n’est pas « sportive », Brulé-Josso (2012) rappelle que « Aujourd’hui, il est très communément dit et écrit que la « plaisance moderne » est née à cette période et que le Centre nautique des Glénans est l’institution qui a contribué à cet avènement. Pour ses fondateurs, l’héritage culturel revendiqué est celui des pêcheurs. ». Ceci nous amène à nous intéresser aux activités nautiques autres que la « voile sportive ». Dans cette communication, nous présenterons comment des associations se sont structurée en un Collectif des Association Nautiques de l’agglomération nantaise pour permettre que la navigation loisir, quasi absente sur la Loire il y a 30 ans, prenne sa place, au même titre que les autres modes de transports loisir sur la Loire et son affluent l’Erdre, en permettant aux habitants de découvrir leur ville à partir de l’eau, en mode déplacement doux. Nous mettrons en particulier l’accent sur la pratique du voile-aviron dont les supports sont parfois inspirés de bateaux utilisés pour la pêche comme les yoles de Ness inspirés de bateaux des îles Shetland.
Experimental study of particle lift initiation on roller-compacted sand-clay mixtures
- Le Vern Mickael
- Sediki Ouardia
- Razakamanantsoa Andry
- Murzyn Frédéric
- Larrarte Frédérique
Environmental Geotechnics, ICE-Publishing , 2024, 11 (1), pp.3-14 . Civil engineering works are sources of dust emissions, which can cause severe security, health and environmental damages to workers and neighbourhoods. This is particularly significant for implementation of earthwork sites. The present paper reports a study conducted to characterise the soil–atmosphere interaction above compacted soils where particle lift is initiated. Mixtures of kaolin clay and sand have been compacted using a laboratory roller compactor that reproduces near-field compaction conditions. Shear testing conducted at the interface confirms that the sand content affects the friction angle between the soil and the compaction roller. The experimental velocity profiles above the compacted samples have been obtained in a wind tunnel using a non-intrusive measurement technique (laser Doppler velocimetry). Results show that the sand fraction affects velocity profiles. Compaction, therefore, may not fully reduce the roughness of the soil surface. The airflow friction velocities at the sample surfaces have been determined from the boundary layer profiles. The results achieved demonstrate that all tested soils reach the threshold friction velocity required to initiate particle lift, and the higher the sand content of the soil, the more likely it is that particle lift occurs. (10.1680/jenge.19.00172)
DOI : 10.1680/jenge.19.00172
Floods in housing estate : some experimental data
- Larrarte Frédérique
- Doumic Augustin
- Goutal Nicole
, 2022, pp.6 p., photos, graph. . The water cycle can be affected by violent events such as earthquakes, tsunamis, floods, ... In France, 17 millions of inhabitants are exposed to flood risk. One challenge during floods is to be able to access to people refugee over buildings. In order to investigate the hydraulic context generated by the grouped obstacles representative of a submerged housing estate, a preliminary experimental study was conducted. We experimentally study the flow in the presence of rows of macro-roughnesses representative of a submerged housing estate, and this for situations representing both current and more intense floods. After presenting the experimental configurations, the experimental results are given and discussed. The first conclusions are completed by the perspectives. (10.3850/iahr-39wc2521716x2022577)
DOI : 10.3850/iahr-39wc2521716x2022577
Structure of open-channel flows through an array of square cylinders
- Oukacine Marina
- Larrarte Frédérique
- Goutal Nicola
Urban Water Journal, Taylor & Francis , 2022, 19 (7), pp.12 p. . The impact of obstacles on the hydrodynamic flow structure is of major interest since such flows are representative of flooded urban areas. This study focuses on a pattern depicting a single-family home and garden area, as found in recent suburban development. The purpose herein is to analyze the evolution of the velocity distribution for a densely built area as well as for emerged to slightly submerged situations, which represent various flood situations ranging from commonplace to extreme. Free-surface flows through an in-line distribution of square cylinders were investigated in a laboratory flume, in the aim of assessing the effect of relative submergence on the flow structure within the cylinder array. The results show that the lines of square cylinders channelize the flow. Moreover, the submerged case generated similar flow characteristics below the top of the cylinders, which drastically changed once the water flowed above the square cylinder level. (10.1080/1573062X.2022.2075771)
DOI : 10.1080/1573062X.2022.2075771
Real time instability of flow close to a scour affected abutment
- Chevalier Christophe
- Larrarte Frédérique
Environmental Fluid Mechanics, Springer Verlag , 2022, 22, pp.495–510 . For centuries, the interaction between the transport and hydrographic networks represents a signifcant issue in a country such as France. For example, the French railway network includes 1700 river-crossing structures and an important length of embankments either forming river banks or adjacent to watercourses exposed to scouring processes. Recently, various cases highlight the importance and vulnerability of civil transport works in relation to their environmental hazards, e.g. foods, and therefore the need to develop integrated observation tools and warning systems in the aim both of optimizing the management system and of increasing the knowledge on real scour processes. This paper relies to a French research project named SSHEAR which objective is to improve understanding of the scouring process through the use of innovative observation tools and physical and numerical hydraulic modelling. This part of the project aims at improving continuous monitoring in order to follow the evolution of the scour processes of a given bridge or abutment. After a presentation of the experimental site, the instrumentation is described as well as its in situ implementation. The data analysis process is given and results are commented before the presentation of some perspectives part. (10.1007/s10652-022-09842-9)
DOI : 10.1007/s10652-022-09842-9
Drafting of 2 swimmers
- Bolon Baptiste
- Pretot Charlie
- Clanet Christophe
- Larrarte Frédérique
- Carmigniani Rémi Arthur
, 2021, pp.1 p. . Open water swimming is a very tactical sport. As in cycling, competitors often swim in peloton formations. Therefore, their position in the group is crucial to optimize drafting, either to preserve their physical strength, to quickly pass a lead swimmer or to impede the passing of an opponent. This work is an experimental study of the drag on 2 swimmers scaled models.
Chapter 3: Water level and discharge measurements
- Larrarte Frédérique
- Lepot Mathieu
- Clemens-Meyer Francois
- Bertrand-Krajewski Jean-Luc
- Ivetić Damjan
- Prodanović Dusan
- Stegeman Bram
, 2021, pp.35-104 . The knowledge of water levels and discharges in urban drainage and stormwater management (UDSM) systems is of key importance to understand their functioning and processes, to evaluate their performance, and to provide data for modelling. In this chapter, devoted mainly to underground combined and separate sewer pipe systems, various methods and technologies are described and discussed. After an introduction to important aspects to deal with when measuring discharges in sewer systems, the following parts are presented successively: (i) measurement of water level with rulers, and pressure, ultrasonic and radar sensors, (ii) measurement of flow velocity with ultrasonic, Doppler, velocity profiler, free surface, and electromagnetic sensors, (iii) direct measurement of discharge with pre-calibrated devices, physical scale models, computational fluid dynamics modelling and use of pumping stations, and (iv) detection and/or measurement of infiltration into and exfiltration from sewers, with flow or pressure measurements, tracer experiments, distributed temperature sensing and geophysical methods. (10.2166/9781789060119_0035)
DOI : 10.2166/9781789060119_0035
Investigation of the hydraulics in flooded housing estate
- Doumic Augustin
- Larrarte Frédérique
- Rtimi Rajae
- Goutal Nicole
, 2021, pp.9 p., graph., photos. . Climate change is currently taking place at the scale of our planet, leading to aviolent response from the environment, particularly with regard to the water cycle. One of the risk is already floods. As an example, in France, the average annual costof damages caused by floods (and insured under the Natural Disaster plan) amounts to 520 million euros. In metropolitan France, nearly 17 million people, about aquarter of the national population, are exposed to the risk of flooding by overflowaccording to the preliminary flood risk assessment carried out by the State in 2011.And with climate evolution, floods will become more frequent and more intense. Onechallenge during floods is to be able to access to people refugee over buildings.In order to investigate the hydraulic context generated by the grouped obstaclesrepresentative of a submerged housing estate, both an experimental and numericalstudy is being conducted.We experimentally study the flow in the presence of rows of macro-roughnesses representative of a slightly emerged and of a submerged housing estate, and this for situations representing both current and more intense floods. Measurements of the velocity field will provide information on currents distribution that might affect an evacuation process. In parallel a numerical study is also conducted with the opensource code Saturne. The numerical results are compared to experimental results and this preliminary stupy opens the way to a systematic investigation. (10.1007/978-981-19-1600-7_19)
DOI : 10.1007/978-981-19-1600-7_19
Experimental flows through an array of emerged or slightly submerged square cylinders over a rough bed
- Oukacine Marina
- Proust Sébastien
- Larrarte Frédérique
- Goutal Nicole
Scientific Data, Nature Publishing Group , 2021, 8 (1) . The experimental dataset presented was collected in an 18 m long and 1 m wide laboratory flume. Low to high flood flows through an urbanized floodplain were modelled. The floodplain bed is rough, modelled with dense artificial grass. A square cylinder array, representing house models, was set on the rough bed. The cylinder immersion rate was varied: cylinders are emerged for three flow cases and slightly submerged for one case. The experimental dataset comprises water levels, measured using an ultrasonic transit time probe, velocities across the channel measured using an Acoustic Doppler Velocimetry with a side looking probe, and velocities in longitudinal-vertical planes measured using Particle Image Velocimetry. These data could help understanding the physical processes associated with high flood flows through urbanized floodplains, with a focus on the transition from emerged to submerged obstacles. They could also be used as benchmark data to assess the ability of numerical models from one to three-dimensions to estimate the flood hazard (water depth, velocity) over a wide range of flood event magnitudes. (10.1038/s41597-020-00791-w)
DOI : 10.1038/s41597-020-00791-w
Drafting of two passive swimmer scale models for open-water races
- Bolon B
- Pretot C
- Clanet Christophe
- Larrarte Frédérique
- Carmigniani R
Soft Matter, Royal Society of Chemistry , 2020, 16 (31), pp.7270-7273 . The interaction between two passive human swimmer scale models is investigated both experimentally and numerically. The Froude number, comparing the swimming velocity to the characteristic wave velocity, is conserved in the study. The interaction is quantified for a large range of relative positions and for three speeds corresponding to cruising, average, and sprint swimming. The associated computational fluid dynamics study using OpenFoam allows us to determine the relative positions that optimize the drafting during an open-water race: just behind a lead swimmer or at the level of the hip of a neighbor, with reductions of drag of 40% and 30%, respectively. (10.1103/PhysRevFluids.00.004800)
DOI : 10.1103/PhysRevFluids.00.004800
Hydraulics and bridges: A French case study of monitoring of a bridge affected by scour
- Larrarte Frédérique
- Chevalier Christophe
- Battist Louis
- Chollet Hugues
Flow Measurement and Instrumentation, Elsevier , 2020, 74, pp.101783 . Bridges are one of the oldest types of civil engineering structures and the interaction between the transport and hydrographic networks represents a significant issue in a country such as France. Recently, various cases highlight the importance and vulnerability of civil transport works in relation to their environmental hazards, e.g. floods, and therefore the need to develop integrated observation tools and warning systems in the aim both of optimizing the management system and of increasing the knowledge on real scour processes. This paper reports on the field approach task of a research project aiming at improving continuous monitoring in order to follow the evolution of the scour processes of a given bridge or abutment. The first step has been to identify a pilot site, representative of scour vulnerability. After a report of the scour parameters to be monitored, the benchmark study and the choice of monitoring devices available on the market are detailed. Instrumentation, sensor adaptability, limitations (actual measurement ranges, ergonomics, energy supply limits ...) and in situ implementation are then presented and discussed. Finally, preliminary measurements, post-treatments and interpretation are detailed. (10.1016/j.flowmeasinst.2020.101783)
DOI : 10.1016/j.flowmeasinst.2020.101783
Large Eddy Simulation for flows through emerged or slightly sub-merged square obstacles
- Oukacine Marina
- Rtimi Rajae
- Goutal Nicole
- Larrarte Frédérique
- Loizeau Vincent
- Benhamadouche Sofiane
- Proust Sébastien
, 2020, pp.8 p. . As a result of climate change, we believe that extreme floods will become more frequent and more intense. The flows through obstacles representing an urbanized floodplain is realised in a laboratory at Re = 4766 and 8580. The purpose of the present study is first to validate a numerical model using Large Eddy Simulation (LES) against experimental data regarding the average longitudinal velocity and the secondary vortices formation. Then, additional data can be obtained and quantified. Therefore the geometrical parameters can be changed and their influence analysed and compared to the literature. A good agreement was found between simulated and experimental vertical profiles of time averaged velocity for the flow through emerged or slightly submerged obstacles. The additional simulations highlight that the flow structure is mostly driven by the transverse aspect ratio using the distance between two adjacent obstacles.
Soils, Structures and Hydraulics: Expertise and Applied Research (SSHEAR) Project
- Chevalier Christophe
- Schmidt Franziska
- Larrarte Frédérique
- Cheetham Mark
- Durand Edouard
- Sergent Philippe
- Gondret Philippe
- de La Roque Sidoine
, 2019, pp.6p . The phenomenon of scouring represents a significant contributing factor in the destabilizing and destruction of civil structures (bridges, earth embankments and buildings) during major flood events, yet our understanding of the mechanisms involved remains highly empirical. These erosive processes are complex and involve many disciplines including soil, fluid and structural mechanics. To overcome the reliance on empiricism, while building general knowledge and proposing optimized methods aimed at diagnostics, advanced warning procedures and infrastructure management, a consortium comprising six complementary partners has been formed within the project SSHEAR (?Soils, Structures and Hydraulics: Expertise and Applied Research?) financially supported by the French National Research Agency (ANR). After a presentation of the project, a first assessment of the achieved results is proposed: experimental developments; numerical modelling; feedback in the field.
A French experience of Structural Health Monitoring of scour affecting river infrastructures
- Larrarte Frédérique
- Schmidt Franziska
- Durand Edouard
- Bontemps Arnaud
- Della Longa Yannick
- Cheetham Mark
- de La Roque Sidoine
- Hosseingholian Mohsen
- Chevalier Christophe
, 2019, pp.3p. . This paper presents a French experience of SHM of structures affected by scour