Article
Engineering, Civil
Yunfei Teng, Lin Lu, Liang Cheng, Feifei Tong, Guoqiang Tang
Summary: A new defect function model is proposed in this paper to predict the first harmonic motion in turbulent wave boundary layer flows. By establishing relationships between model parameters and flow parameters, it is demonstrated that the model can predict flow better and extend the applicable parameter ranges.
COASTAL ENGINEERING
(2022)
Review
Engineering, Aerospace
William J. Devenport, K. Todd Lowe
Summary: This article presents a review of historical and recent developments in the understanding of equilibrium and non-equilibrium turbulent boundary layers at incompressible high-Reynolds number conditions. The review focuses on the mean flow, turbulence stress fields, and instantaneous structure, discussing smooth wall and rough wall boundary layers as well as equilibrium and non-equilibrium two-dimensional flows. It concludes with a detailed discussion of boundary layer development in skewed, three-dimensional flows over smooth walls.
PROGRESS IN AEROSPACE SCIENCES
(2022)
Article
Mechanics
Vijit Rathore, Subhasish Dey, Nadia Penna, Roberto Gaudio
Summary: This study investigates the turbulent flow characteristics over an abrupt step change in bed roughness using a Particle Image Velocimetry system, revealing the impact of bed roughness on the flow field. Key findings include changes in Reynolds stresses and bed shear stresses in response to the abrupt change in bed roughness, as well as the creation of a roughness-induced layer that grows over the downstream bed. Bursting analysis suggests that sweeps govern the near-bed flow on the downstream bed, while ejections prevail far from the bed.
Article
Mechanics
C. Peruzzi, D. Vettori, D. Poggi, P. Blondeaux, L. Ridolfi, C. Manes
Summary: This study investigates the alterations in turbulence in open-channel flows caused by the passage of surface waves, using experimental data collected in a laboratory flume facility. By decomposing the velocity signal and proposing a novel outer length scale, the study identifies a genuine overlap layer and provides insights into turbulent statistics in the current-dominated flow region.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Thermodynamics
Bo Zhang, Shihe Yi, Haibo Niu, Xiaolin Liu, Xiaoge Lu, Lin He
Summary: This paper experimentally investigates the effect of Reynolds number on the second-mode waves in hypersonic boundary layer using the NPLS technique and fast response pressure sensors. The flow visualization results capture the characteristics of second-mode waves and their relationship with Reynolds number and streamwise distance. The experimental results agree well with the theoretical estimation values, providing potential feasibility for predicting characteristic frequency and wavelength in other tunnels.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2023)
Article
Mechanics
Davide Modesti, Sebastian Endrikat, Nicholas Hutchins, Daniel Chung
Summary: The study conducted direct numerical simulations on the impact of riblets on turbulent flow, revealing the drag change patterns of different riblet geometries and emphasizing the drag increase associated with dispersive stresses carried by secondary flows.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Gregory LeClaire Wagner, Nick Pizzo, Luc Lenain, Fabrice Veron
Summary: This paper investigates the complex chain of events that occur when a light breeze causes ripples on calm water, eventually leading to the formation of a turbulent shear layer. The study compares laboratory experiments with numerical simulations and validates the wave-averaged model. However, the simulations also reveal a sensitivity to the prescribed surface wave amplitude.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Matthew A. Subrahmanyam, Brian J. Cantwell, Juan J. Alonso
Summary: This paper introduces a mixing length model for turbulent shear stress in pipe flow and provides a universal velocity profile. The velocity profile accurately approximates both experimental and simulated data in various flow conditions, making it significant for studying the statistical properties of flow.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Engineering, Aerospace
Andreas Gross, Jesse Little, Hermann F. Fasel
Summary: This study investigates turbulent shock-wave boundary layer interactions at a freestream Mach number of 2.3 using a hybrid turbulence model and large-eddy simulations. The research findings indicate that the sweep angle has a significant effect on the structures and pressure fluctuations.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Engineering, Aerospace
Giacomo Della Posta, Marco Fratini, Francesco Salvadore, Matteo Bernardini
Summary: This study presents direct numerical simulations of a turbulent boundary layer on a microramp to investigate the impact of Mach number on the flow. The study finds that the flow topology changes significantly due to compressibility effects and the typical wake features are not linearly scaled with the geometry dimensions but depend on the incoming flow conditions. Furthermore, the study explores the spectral content in time and space of the wake, with Kelvin-Helmholtz instability dominating along the shear layer. The shedding onset is postponed and exhibits a lower peak frequency that evolves in space for larger Mach numbers.
Article
Engineering, Marine
N. Hutchins, B. Ganapathisubramani, M. P. Schultz, D. I. Pullin
Summary: A new method based on power mean is proposed to define an equivalent homogeneous roughness length that considers the heterogeneous distribution of roughness on ship hulls. The method can be easily incorporated into existing drag prediction methods. The study shows that the relationship between drag coefficient and roughness length is non-linear, indicating a source of error in current approaches. The power-mean approach has low errors for both skewed beta distributions and fully-rough models, and retains accuracy in transitional regimes and with different roughness models.
Article
Mechanics
S. Unnikrishnan, Datta V. Gaitonde
Summary: This study demonstrates that wall cooling has a significant impact on instabilities and transition processes in hypersonic boundary layers, accelerating instability growth and leading to stronger destabilization effects. The simulations and analysis of boundary layers under different wall temperature conditions reveal that wall cooling results in faster transition and significantly affects wall loading.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Xudong Tian, Chihyung Wen
Summary: Stability analyses based on perturbation rates were used to study the growth mechanisms of second-mode instability in hypersonic boundary layers. The results revealed the interactions of streamwise velocity, wall-normal velocity, and fluctuating internal energy, with wall-normal velocity perturbation playing a key role in the growth of second-mode instability, dependent on the relative phase with the total time rate of change of fluctuating internal energy near the critical layer.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Christoph Wenzel, Tobias Gibis, Markus Kloker, Ulrich Rist
Summary: This study quantitatively evaluates the Reynolds analogy factor for self-similar turbulent boundary layers with pressure gradients using direct numerical simulation. The factor is found to increase for adverse-pressure-gradient cases and decrease for favourable-pressure-gradient cases. Mach number has a small influence, and no dependency on Reynolds number was observed. The effects of pressure gradients can be approximated by an analytical relation derived by So in incompressible flow.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Rahul Deshpande, Charitha M. de Silva, Ivan Marusic
Summary: We provide experimental evidence that the superstructures in turbulent boundary layers are made up of smaller coherent motions that are geometrically self-similar. Through analysis of high Reynolds number particle image velocimetry datasets, we identify and analyze instantaneous superstructures capable of capturing elongated motions up to 12 times the boundary layer thickness. A new approach is taken to identify the constituent motions of the superstructures, by analyzing the wall-normal velocity fluctuations within these long motions. The findings support data-driven modeling of these dynamically significant motions using coherent structure-based models.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Environmental Sciences
Cristina Prieto, Nataliya Le Vine, Dmitri Kavetski, Eduardo Garcia, Raul Medina
WATER RESOURCES RESEARCH
(2019)
Article
Meteorology & Atmospheric Sciences
Helios Chiri, Ana Julia Abascal, Sonia Castanedo, Jose Antonio A. Antolinez, Yonggang Liu, Robert H. Weisberg, Raul Medina
Article
Computer Science, Interdisciplinary Applications
O. Quetzalcoatl, M. Gonzalez, V Canovas, R. Medina, A. Espejo, A. Klein, M. G. Tessler, L. R. Almeida, C. Jaramillo, R. Gamier, N. Kakeh, J. Gonzalez-Ondin
ENVIRONMENTAL MODELLING & SOFTWARE
(2019)
Article
Environmental Sciences
June Gainza, Roland Garnier, Paula Nunez, Camilo Jaramillo, Ernesto Mauricio Gonzalez, Raul Medina, Pedro Liria, Irati Epelde, Adolfo Uriarte, Manu Monge-Ganuzas
JOURNAL OF COASTAL RESEARCH
(2019)
Article
Environmental Sciences
Helios Chiri, Ana Julia Abascal, Sonia Castanedo, Raul Medina
MARINE POLLUTION BULLETIN
(2019)
Article
Engineering, Civil
Paula Gomes da Silva, Raul Medina, Mauricio Gonzalez, Roland Garnier
COASTAL ENGINEERING
(2019)
Article
Engineering, Civil
Camilo Jaramillo, Martinez Sanchez Jara, Mauricio Gonzalez, Raul Medina
COASTAL ENGINEERING
(2020)
Article
Geography, Physical
E. Pellon, L. R. de Almeida, M. Gonzalez, R. Medina
Article
Ecology
Jose A. Juanes, A. G. Gomez, S. Rubio, G. Garcia-Castrillo, A. Puente, B. Ondiviela, R. Medina
REGIONAL STUDIES IN MARINE SCIENCE
(2020)
Article
Oceanography
P. Nunez, S. Castanedo, R. Medina
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2020)
Article
Engineering, Civil
Camilo Jaramillo, Mauricio Gonzalez, Raul Medina, Imen Turki
Summary: Beach rotation is an important phenomenon influenced by periodic or long-term changes in wave climate. This study presents an equilibrium-based shoreline rotation model and validates its accuracy and reliability through actual beach data.
COASTAL ENGINEERING
(2021)
Article
Environmental Sciences
Cristina Prieto, Dmitri Kavetski, Nataliya Le Vine, Cesar Alvarez, Raul Medina
Summary: In hydrological modeling, a statistical hypothesis-testing perspective on model identification challenge is presented. A mechanism identification framework is proposed, combining Bayesian estimation, test statistic, and flexible modeling framework. The method is reliable in identifying dominant mechanisms, but statistical power decreases as data/model errors increase. Insights on process identifiability are reported, and the method is expected to contribute to improving model identification in hydrology.
WATER RESOURCES RESEARCH
(2021)
Article
Marine & Freshwater Biology
Paula Nunez, Sonia Castanedo, Raul Medina
Summary: This study uses numerical models to investigate the impact of estuary morphology on the distribution of plastic debris in tidal estuaries. Findings show that asymmetry at the mouth influences flood/ebb dominance, affecting the presence of plastic debris in areas where tidal flow is favored. Additionally, the study highlights the regulatory role of kurtosis in correcting the fate of plastic debris influenced by skewness.
ESTUARINE COASTAL AND SHELF SCIENCE
(2021)
Article
Engineering, Civil
Camilo Jaramillo, Martinez Sanchez Jara, Mauricio Gonzalez, Raill Medina
Summary: This study introduces a new equilibrium shoreline evolution model specifically for embayed beaches, providing predictions of shoreline change over various time scales. The model has shown good performance in the Collaroy-Narrabeen embayment in Australia, but further validation in diverse beach settings is necessary.
COASTAL ENGINEERING
(2021)
Article
Engineering, Civil
E. Pellon, I Aniel-Quiroga, M. Gonzalez, R. Medina, C. Vidal
Summary: Beach accretion is the natural mechanism for dry beaches to recover. Human response to climate change and the marine climate increase beach erosion and hinder full recovery. Beach nourishment and beach scraping are used worldwide to fight coastal erosion in an environmentally friendly manner.
COASTAL ENGINEERING
(2023)
Article
Engineering, Civil
Kuifeng Zhao, Yufei Wang, Philip L. -F. Liu
Summary: This note provides guidelines for selecting appropriate analytical periodic water wave solutions based on two physical parameters. The guidelines are summarized in a graphic format and the dividing lines between applicable wave theories are determined by the nonlinearity and frequency dispersion ratios.
COASTAL ENGINEERING
(2024)
Article
Engineering, Civil
Jana Haddad, Johanna H. Rosman, Richard A. Luettich, Christine M. Voss
Summary: Understanding wave transformation in marsh vegetation canopies is crucial for assessing nature-based shoreline strategies. This study investigates the challenges of accurately modeling wave dissipation in coastal marshes and proposes a new dimensionless parameter to represent the canopy drag coefficient (C-D). The study finds that uncertainties in vegetation measurements lead to variations in C-D expressions, and suggests using the Cauchy number (Ca) as the more appropriate parameter for larger waves.
COASTAL ENGINEERING
(2024)
Article
Engineering, Civil
Dirk P. Rijnsdorp, Arnold van Rooijen, Ad Reniers, Marion Tissier, Floris de Wit, Marcel Zijlema
Summary: This paper extends the non-hydrostatic wave-flow model SWASH to account for the influence of a depth-uniform ambient current on wave dynamics. The model's ability is verified by comparing predictions to results from linear theory, laboratory experiments, and a spectral wave model. The extended model accurately captures current-induced changes in the wave field and simulations of wave dynamics in the presence of strong opposing currents.
COASTAL ENGINEERING
(2024)
Article
Engineering, Civil
Zhihao Shen, Duruo Huang, Gang Wang, Feng Jin
Summary: In this study, a resolved CFD-DEM coupling procedure was proposed to study the interaction of waves and irregularly shaped armour units. The model was validated by comparing the numerical results with a flume wave erosion test. The influence of armour shape on overtopping discharge, pressure distribution, and vortex structure was also studied.
COASTAL ENGINEERING
(2024)
Article
Engineering, Civil
Xinyu Hou, Zhonghua Weng, Xin Chen, Gengfa Chen
Summary: A single-phase model is proposed to predict sediment motion on vortex rippled bed under wave action. The model takes into account the acceleration effect of bottom sediment, the development of asymmetric boundary layer, and the sediment phase-lag, and successfully predicts the velocity, concentration, and development of sediment cloud on vortex ripples.
COASTAL ENGINEERING
(2024)
Article
Engineering, Civil
Mark Loveland, Eirik Valseth, Jessica Meixner, Clint Dawson
Summary: This article discusses the importance of using numerical models to predict the wind wave spectrum of the ocean. The article explores various finite element discretizations of the Wave Action Balance Equation and examines their convergence properties through simplified 2-D test cases. It also introduces a new spectral wind wave model called WAVEx and its implementation method.
COASTAL ENGINEERING
(2024)
Article
Engineering, Civil
Yuan Li, Chi Zhang, Shaohua Zhao, Hongshuai Qi, Feng Cai, Jinhai Zheng
Summary: Sandy-muddy transitional beaches (SMT-Beaches) are a type of coastal formation consisting of upper sandy beach and lower mudflat. This study examined the morphological characteristics of SMT-Beaches and the mechanisms of the formation of sandmud transition (SMT) boundary. Field surveys were conducted on SMT-Beaches in South China Coasts and a new equilibrium profile function for SMT-Beaches was developed. The function demonstrated good performance and improved accuracy compared to traditional methods. It was also found that sediment characteristics differ on both sides of the SMT boundary, with clay-to-silt grains increasing seaward.
COASTAL ENGINEERING
(2024)
Article
Engineering, Civil
He Ma, Ludi Xu, Samuel Ukpong Okon, Peng Hu, Wei Li, Huabin Shi, Zhiguo He
Summary: This study presents a coupled model to predict morphodynamic changes during storm surges. The model accurately simulates the morphological evolution of the Santa Rosa barrier island caused by Hurricane Ivan's storm surge.
COASTAL ENGINEERING
(2024)
Article
Engineering, Civil
Myung Jin Koh, Hyoungsu Park, Albert S. Kim
Summary: A framework combining tsunami flow model and debris transport model is developed to evaluate the kinematics of multiple debris and sequential hazards in a coastal community. The impact of tsunami-driven debris at Honolulu Harbor, Hawaii is assessed by simulating the motion of 2500 shipping containers under a hypothetical tsunami event. New types of intensity measures for tsunami-driven debris hazards are introduced, and hazard maps showing the potential impact loadings from debris dispersion are presented.
COASTAL ENGINEERING
(2024)