Search

This paper, based on a keynote presented at the MARE People and the Sea Conference 2023 as well as on material from A Book of Waves, examines how oceanographers and coastal engineers in the United States, the Netherlands, Australia, Japan, and Bangladesh study and represent waves. Waves, seen as both chaotic and ordered, ephemeral and enduring, offer insights into how science engages with environmental, national, and planetary futures. The discussion begins in the Netherlands, where centuries-old efforts to resist waves in a nation below sea level have evolved into “building-with-nature” strategies, reframing waves as collaborators in environmental resilience. Historical contexts, from wave folklore to physical scale models, underpin this shift in Dutch wave science. Next, I explore the wave simulation laboratory at Oregon State University, where researchers model tsunami risks from the Cascadia fault line. These experiments connect the Pacific Northwest with Japan’s tsunami research, highlighting challenges in adapting wave knowledge across regions. Finally, I turn to Bangladesh’s Ganges Delta, where Dutch hydrological expertise was applied in mid-20th-century development projects, often with uneven results. This case illustrates the complexities of transposing wave science into diverse settings. I conclude by reflecting on how these scientific practices contribute to understanding the Anthropocene, particularly from the perspective of the Global South’s oceans. [ABSTRACT FROM AUTHOR]

The emerging industry of offshore wind turbines mounted on floating bases has garnered significant attention from both academia and industry. The desire to understand the complex physics of these floating structures has led to the development of numerical and physical modelling techniques. While physical testing has traditionally been employed, there is a growing focus on cost-effective and accurate high-fidelity numerical modelling as a potential alternative or supplement. However, commonly used numerical engineering tools in the offshore industry are considered mid- to low-fidelity and may lack the desired precision for floating offshore wind turbines (FOWTs). Given the complexity of these simulation codes, it is crucial to validate their accuracy. To address this, the International Energy Agency (IEA) Wind Technology Collaboration Programme initiated various research endeavors, including the Offshore Code Comparison Collaboration (OC3), Offshore Code Comparison Collaboration Continuation (OC4), Offshore Code Comparison Collaboration Continuation with Correlation (OC5), and the recent Offshore Code Comparison Collaboration Continued with Correlation and Uncertainty (OC6) projects. This study offers a comprehensive survey of the simulation tools available for FOWTs which were part of OC projects, focusing particularly on horizontal axis wind turbines (HAWTs) and highlighting their capabilities and fundamental theories. [ABSTRACT FROM AUTHOR]

The emerging industry of offshore wind turbines mounted on floating bases has garnered significant attention from both academia and industry. The desire to understand the complex physics of these floating structures has led to the development of numerical and physical modelling techniques. While physical testing has traditionally been employed, there is a growing focus on cost-effective and accurate high-fidelity numerical modelling as a potential alternative or supplement. However, commonly used numerical engineering tools in the offshore industry are considered mid- to low-fidelity and may lack the desired precision for floating offshore wind turbines (FOWTs). Given the complexity of these simulation codes, it is crucial to validate their accuracy. To address this, the International Energy Agency (IEA) Wind Technology Collaboration Programme initiated various research endeavors, including the Offshore Code Comparison Collaboration (OC3), Offshore Code Comparison Collaboration Continuation (OC4), Offshore Code Comparison Collaboration Continuation with Correlation (OC5), and the recent Offshore Code Comparison Collaboration Continued with Correlation and Uncertainty (OC6) projects. This study offers a comprehensive survey of the simulation tools available for FOWTs which were part of OC projects, focusing particularly on horizontal axis wind turbines (HAWTs) and highlighting their capabilities and fundamental theories.

Abstract Modelling floating offshore wind turbines (FOWTs) is challenging due to the strong coupling between the aerodynamics of the turbine and the hydrodynamics of the floating platform. Physical testing at scale is faced with the additional challenge of the scaling mismatch between Froude number and Reynolds number due to working in the two fluid domains, air and water. In the drive for cost‐reduction of floating wind energy, designers may be seeking to move towards high‐fidelity numerical modelling as a substitute for physical testing. However, the numerical engineering tools typically used for FOWT modelling are considered as mid‐fidelity to low‐fidelity tools, and currently lack the level of accuracy required to do so. Furthermore, there is a lack of operational FOWT data available for further development and validation. High‐fidelity tools, such as CFD, have greater accuracy but are cumbersome tools and still require validation. Physical scale model testing therefore continues to play an essential role in the development of FOWTs both as a source of validation data for numerical models and as an important development step along the path to commercialization of all platform concepts. The aim of this paper is to provide an overview of both numerical modelling and physical FOWT scale model testing approaches and to provide guidance on the selection of the most appropriate approach (or combination of approaches). The current state‐of‐the‐art will be discussed along with current research trends and areas for further investigation.

In order to foresee the response during the fire of a real symmetrical structure (prototype), nowadays engineers apply methods which involve the associated reduced-scale model's behaviors, mainly dimensional analysis behaviors. Between the dimensional analysis methods, the so-called Modern Dimensional Analysis (MDA), developed by Szirtes, fulfills all engineering requirements compared with the classical one. The authors used this new proposed method to describe their original electric fire simulation testing bench, as well as the Model Law (using MDA) for the heat transfer in tubular rectangular bars. So, a validation of the Model Law was performed based on several scrupulous experimental investigations both on a real column's segment and its associated reduced-scale models manufactured at 1:2; 1:4, as well as 1:10 scales. The original heating system, the elaborated protocol, the deduced Model Law, and the results of the experimental investigations represent the contributions of the authors in the field of metallic structures subject to fires. The results validate the possibility of using MDA in the case of heat transmission. [ABSTRACT FROM AUTHOR]

We estimate yields and source depths for the six North Korean underground nuclear explosions (UNEs) in 2006, 2009, 2013, 2016 (January and September), and 2017, based on regional seismic observations in South Korea. Spectral ratios of event pairs are calculated using seismograms from the six UNEs observed along the same propagation paths and at the same receivers. These relative seismic source scaling spectra for Pn provide a basis for a grid search source solution that estimates source yields and depths for each event pair based on assumed explosion source models by Mueller and Murphy (1971; MM71), Denny and Johnson (1991; DJ91), and Walter and Ford (2018; WF18). The grid search is used to identify the best fit to the empirical spectral ratios subject to the source models by minimizing the root mean square misfit in the frequency range of 0.2-15 Hz. To address the trade-off between depth and yield, a modified grid search was implemented that includes elastic propagation effects for different source depths using reflectivity Green's functions, thus modeling slight differences in propagation path based on source depth. This addition reduces trade-offs between depth and yield, and results in better model fits to frequencies as high as 15 Hz compared with cases in which depth effects were not included. The modified grid search results indicate that both MM71 and WF18 models provide comparable source depth and yield estimates with good agreement between theoretical and observed spectral ratios matching both the long-period levels and the corner frequencies, whereas the DJ91 model estimates produce lower yields due to a difference in corner frequency scaling. The best grid search solutions produce yields from ~0.9 kt for the first UNE and up to ~290 kt for the explosion in 2017, with depths varying from ~280 to ~750 m. [ABSTRACT FROM AUTHOR]

Modelling floating offshore wind turbines (FOWTs) is challenging due to the strong coupling between the aerodynamics of the turbine and the hydrodynamics of the floating platform. Physical testing at scale is faced with the additional challenge of the scaling mismatch between Froude number and Reynolds number due to working in the two fluid domains, air and water. In the drive for cost‐reduction of floating wind energy, designers may be seeking to move towards high‐fidelity numerical modelling as a substitute for physical testing. However, the numerical engineering tools typically used for FOWT modelling are considered as mid‐fidelity to low‐fidelity tools, and currently lack the level of accuracy required to do so. Furthermore, there is a lack of operational FOWT data available for further development and validation. High‐fidelity tools, such as CFD, have greater accuracy but are cumbersome tools and still require validation. Physical scale model testing therefore continues to play an essential role in the development of FOWTs both as a source of validation data for numerical models and as an important development step along the path to commercialization of all platform concepts. The aim of this paper is to provide an overview of both numerical modelling and physical FOWT scale model testing approaches and to provide guidance on the selection of the most appropriate approach (or combination of approaches). The current state‐of‐the‐art will be discussed along with current research trends and areas for further investigation. [ABSTRACT FROM AUTHOR]

The paper concerns the dimensional analysis of simple acoustic metamaterials and its experimental verification in a computer model. Due to their decreased thickness possible because of the thermoviscous losses and sound dispersion that occur in acoustic metamaterials, such structures are gaining popularity, both as sound absorbers and diffusers. This implies the need to find their equivalents to be used at scale - both for modeling interiors with metamaterials and developing more complicated structures. The paper discusses the dimensional analysis performed for a generalized unit cell of a metamaterial with a resonator. The dimensional analysis shows the need for scaling both the geometrical dimensions of the structure and the parameters of the medium - air. The dimensional analysis was derived based on the transfer matrix method and was proven correct with the finite element method model. The paper also discusses the consequences of neglecting the air criteria, which are impossible to be fulfilled. This opens the question of finding new criterial numbers allowing the correct reflection of acoustic metamaterials at scale. [ABSTRACT FROM AUTHOR]

The cofferdam built at the inlet of the diversion tunnel may be left due to incomplete blasting demolition, which affects the river closure. Several indexes have been used to evaluate the difficulty of river closure, but all indexes suffer from their limitations in use. Thus, it is more useful to combination multiple indexes to analyze the impact of residual cofferdam. Taking the river closure project of a Hydropower Station in southwest China as an example, the influence of the residual cofferdam heights on the river closure was studied by experiments. The discharge of river closure is 590 m3/s and 758 m3/s. In this paper, the results of studies on a 1:50 scale hydraulic model based on the Froude similitude relationships are presented. The test results show that the discharge capacity of the diversion tunnel is reduced by 27.2% at most when this height is more than 2 m. The residual height mainly affects the maximum of stream energy with unit width, which increase by more than 50% at most compare to Non-existent residual cofferdam. However, the final drop, max-velocity along the gap axis, the local scour of riverbed and the flow pattern of the gap are basically not affected. In addition, with the height increase, the bank collapse is intensified, and the amount of dumped material with medium size increases, especially when it reaches 4 m, the large or Extra-large size stones begin to be dumped. Based on the comprehensive evaluation of multiple indexes and the type of dumped material, it is shown that the residual cofferdam height more than a certain value, the value is 2 m for the case study, will significantly increase the river closure difficult.

For a long time, scale models were the most effective means of communication to depict architecture and cities. Free from the constraints of the graphical representation, the third dimension allows a simplified reading of the depicted object. Beyond the question of replacing the model with increasingly realistic and immersive digital mediations, our communication investigates the processes at work in projects as well as the dialogue between physical and digital models. Over the past twenty years or so, a growing number of projects have brought together models and digital science. Archiving and valorisation of scale models are objectives shared by most projects, while a minority aspires to reconstitute past environments and create multidimensional information systems to interface the data relating to scale models. Some forty projects involving old city models were studied, including MAP’s digitalization program for plans-reliefs. While 3D acquisition is the first step in most of the projects studied —and despite advances in data collection— the exceptional properties of scale models are a first challenge. At the other end of the production chain, the final product (nD information system, physical replica, augmented scale models, film, etc.) is also analysed to identify the uses and forms of dialogues that are established between physical model, digital model and knowledge relating to these media. This paper synthesizes the objectives, challenges, production and dissemination methods at work in these approaches and introduces the ‘Urbania’ project, the latest research of MAP on the digitisation of relief planes.

3D models of chemical structures are an important tool for chemistry lectures and exercises. Usually, simplified models based on standard bond length and angles are used. These models allow for a visualized discussion of (stereo)chemical aspects, but they do not represent the true spatial conditions. 3D-printing technologies facilitate the production of scale models. Several protocols describe the process from X-ray structures, calculated geometries or virtual molecules to printable files. In contrast, only a few examples describe the integration of scaled models in lecture courses. True bond angles and scaled bond lengths allow for a detailed discussion of the geometry and parameters derived therefrom, for example double bond character, aromaticity and many more. Here, we report a complete organic chemistry/stereochemistry lecture course and exercise based on a set of 37 scale models made from poly(lactic acid) as sustainable material. All models have been derived from X-ray structures and quantum chemical calculations. Consequently, the models reflect the true structure as close as possible. A fixed scaling factor of 1 : 1.8·108 has been applied to all models. Hands-on measuring of bond angles and bond length leads to an interactive course. The course has been evaluated with a very positive feedback.

In 1976–77 the Institute for Architecture and Urban Studies (IAUS) in New York organised Idea as Model, an exhibition of architectural models realised by 22 architects and architects' teams. Many participants can be considered protagonists of postmodern architecture, including Michael Graves, John Hejduk, Robert Stern and Stanley Tigerman, Mario Gandelsonas, Léon Krier, Charles Moore, Massimo Scolari and Oswald Mathias Ungers. This article revisits Idea as Model in relation to then-raging discussions regarding the use of models and drawings in modernism and postmodernism and the debates about the respective "limits" of architecture and art. Framed as a response to architecture shows in New York and as a product of the aims of then-IAUS director Peter Eisenman, Idea as Model is described both as characteristic of postmodernism and as reverberating with the long-standing suspicion among architects over the ambiguities of the scale model. [ABSTRACT FROM AUTHOR]

The similarity theory was used to study the behavior of five anchoring and one "rezon" type deadweight designs, using scale models. The surface sediments extracted from Charagato Bay, Cubagua Island, were characterized to evaluate the efficiency of these models on these substrates. A test structure consisting of a tank with a mixture of sediment and seawater, and a metal trestle was used. Tension variables were considered, using a 6 mm PE end section. Weights were added at one of its ends which represented the longline system's resistance force and at the other the model's force in the eyebolt (Tc) representing the gripping force due to the interaction of the anchoring design with the substrate, and the static rupture tension (Tr) upon the weight (Pm) of each model, against different anchoring attack angles (?), aspect ratios (AR) 1/2.5; 1/3.0; 1/3.5, and 1/4.0; sail attack angles (?) of 0, 10, and 20°, and the efficiency index (EI) of each model. The Kruskal-Wallis contrast was used to detect the possible differences against different anchoring attack angles, and, to locate the differences between them; box and mustache graphs were used. The most effective model on very fine sandtype sediment was the pyramidal with the claw-like frame, followed by the pyramidal with the shovel-like frame and the "rezon" type traditionally used on Margarita Island. [ABSTRACT FROM AUTHOR]

Geometrically distorted scale models have been a valuable tool for physical modeling of urban flooding in a network of streets. However, little is known so far about the bias induced in such cases by the model geometric distortion. Here, we use 2‐D computational modeling to provide a first systematic quantification of this bias in the case of a synthetic urban layout. The bias is found to be generally small, with the maximum deviations of the upscaled flow depth and discharge partition from the corresponding values of the undistorted model being around 10% in the case of relatively rapid and shallow flow conditions. When the geometric distortion is increased, the computations reveal a nonmonotonous pattern of the flow variables (depth, discharge partition, and size of flow separation zones), which results from a competition between declining frictional losses and growing local losses in the model. These findings may guide the design of distorted scale models of urban flooding and assist the interpretation of laboratory observations for assessing flood protection measures, for process understanding or for validating computational modeling. Plain Language Summary: Data from laboratory experiments are a valuable complement to field observations for validating flood risk management tools. Recent studies of urban flooding in a network of streets have used geometrically distorted scale models (i.e., involving distinct horizontal and vertical scale factors). This geometric distortion may lead to biases such as alteration of flow regime and of flow structures. Here, we use computational modeling to present a systematic quantitative analysis of the biases induced by geometric distortion in laboratory models of urban flooding. Key Points: The bias induced by model geometric distortion on water depths and discharge partition does not exceed 10% in the tested configurationsA nonmonotonous pattern of flow variables is found when varying distortion ratio, reflecting variations in frictional and local head lossesThe findings of the study provide guidance for the design and sizing of geometrically distorted laboratory models of urban flooding [ABSTRACT FROM AUTHOR]