Article
Mechanics
K. Jain, A. I. Ruban, S. Braun
Summary: This paper investigates the receptivity of the boundary layer to suction/blowing in marginally separated flows, showing that two-dimensional perturbations initially grow inside the separation region but decay downstream, while three-dimensional perturbations form a wave packet downstream of the perturbation source in the boundary layer.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Geosciences, Multidisciplinary
S. M. Hamze-Ziabari, A. M. Razmi, U. Lemmin, D. A. Barry
Summary: Submesoscale filaments have been found in Lake Geneva for the first time based on high-resolution 3D numerical simulations, field observations, and remote sensing imagery. These filaments are formed during summertime and have significant impacts on the biophysical processes in the lake.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Mechanics
Henrique Raposo, Shahid Mughal, Antoine Bensalah, Richard Ashworth
Summary: The study investigates the generation of viscous-inviscid instability through scattering of an acoustic wave by localized and distributed roughness on an aerofoil, using a time-harmonic compressible adjoint linearized Navier-Stokes approach. The research models the inviscid acoustic field external to the aerofoil boundary layer and shows that the externally imposed acoustic pressure field drives the acoustic boundary layer, affecting the amplitudes of acoustic-roughness receptivity. Parametric studies reveal significant non-parallel effects and higher receptivity amplitudes for distributed roughness at lower angles of attack.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Youcheng Xi, Jie Ren, Liang Wang, Song Fu
Summary: This study obtained the characteristics of the leading attachment-line mode with sweep angle variations and successfully applied a bi-orthogonal eigenfunction system to address the receptivity problem of hypersonic flows. The analyses showed that global modes are most responsive to external forces and surface perturbations near the attachment line.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Alexander J. Smits, Marcus Hultmark, Myoungkyu Lee, Sergio Pirozzoli, Xiaohua Wu
Summary: The new scaling shows a Reynolds-number-independent profile for all components of the Reynolds stress in the near-wall region of wall-bounded flows, highlighting the significance of wall shear stress fluctuations and the role of large eddies in determining the Reynolds number dependence of near-wall turbulence behavior.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Xiao-Hua Fan, Gang Wang, Jing-Zhou Lin, Yan-Guang Yang, Zhi-Gong Tang
Summary: The experiment investigates the effects of expansion waves on incident shock-wave/boundary-layer interactions at Mach 4.96. The flow characteristics of the interaction zone are quantitatively analyzed under different intensities and positions of the incident shock wave and expansion waves. The expansion waves weaken the intensity of the shock waves encountered, thereby weakening the strength of the SWBLIs. The total wall pressure jump and interference length show a linear growth trend with increasing distance between the expansion waves and the interaction zone. However, the expansion waves have no impact on the initial pressure jump of the separation, consistent with the free-interaction theory. Finally, the scaling model proposed by Souverein et al. [A scaling analysis for turbulent shock-wave/boundary-layer interactions, J. Fluid Mech. 714, 505 (2013)] is modified using the measured pressure jump value, providing a better approximation for SWBLIs under the influence of expansion waves.
Article
Mechanics
Tie Wei, Zhaorui Li, Tobias Knopp, Ricardo Vinuesa
Summary: Researchers derived an analytical formulation for the mean wall-normal velocity in turbulent boundary layers and validated its accuracy and robustness through comparisons with numerical simulation data. They also investigated the physical significance of the formulation and its connection to predicting the behavior of turbulent boundary layers.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Geosciences, Multidisciplinary
Isabel L. McCoy, Daniel T. McCoy, Robert Wood, Paquita Zuidema, Frida A. -M. Bender
Summary: This study uses a supervised neural network algorithm to categorize global satellite retrievals into three mesoscale cellular convective (MCC) cloud morphology patterns. These patterns differ in brightness associated with the amount of optically thin cloud features. The transitions from closed MCC to other morphology patterns, typically accompanied by more optically thin cloud features, are quantified to understand the contribution of morphology to the optical depth component of the shortwave cloud feedback. The results show that under projected environmental changes, the morphology shifts in optical depth between 65 degrees S and 65 degrees N contribute between 0.04 and 0.07 W m(-2) K-1 (aggregate of 0.06) to the global mean cloud feedback.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Mechanics
Joan Gomez, Huidan Yu, Yiannis Andreopoulos
Summary: The primary focus of this experimental work is the instability and transition to turbulence in pulsatile flows, which involve reverse flows and unsteady flow separations. By conducting experiments with different Reynolds and Womersley numbers, it was found that transition to turbulence is a spontaneous event covering the whole near-wall region.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Zehao Li, Zhigang Zuo, Zhongdong Qian
Summary: In this study, the characteristics of hydrodynamic cavitation bubbles generated from a crevice in near-wall shear flows were experimentally and theoretically investigated. The frequency of the bubbling was found to be highly sensitive to the content of non-condensable gas. Based on the experimental observations, a physical process of periodic bubbling was summarized and a theoretical explanation for the observed cavitation threshold and frequency was provided.
Article
Mechanics
Pierre Ricco, Martin Skote
Summary: The study shows that the Fukagata et al.’s identity simplifies to the von Kaman momentum integral equation for free-stream boundary layers. It is found that the influence of Reynolds stresses on wall-shear stress cannot be quantified for free-stream boundary layers. Analogous identities are found for channel flows, where the laminar and turbulent contributions to the skin-friction coefficient are distinguished. The study also decomposes the skin-friction coefficient into integral thicknesses to quantify the contributions of different terms of the streamwise momentum equation to friction drag.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
A. Khraibut, S. L. Gai
Summary: This paper presents a numerical investigation on the effects of bluntness and incidence on the leading-edge separation in a laminar hypersonic flow. The results show that both bluntness and incidence have significant influences on the separation characteristics. A combined parameter is proposed and applied to plateau pressures in the separated region, differentiating the effects of small and large bluntness at different angles of incidence. The study also highlights the importance of the relationship between the two shear stress minima and the separation length.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Cheng Cheng, Wei Shyy, Lin Fu
Summary: A new methodology was developed to assess the distribution of wall-attached eddies, revealing that the SIAs depend on the Reynolds number at low and medium Reynolds numbers, saturating at 45 degrees as the Reynolds number increases. The average SIA reported in previous experimental studies was shown to be the result of the additive effect of multi-scale attached eddies.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Xue Chen, Yongmann M. M. Chung, Minping Wan
Summary: The statistical characteristics and evolution of backflow structures in wall-bounded flows at Reynolds numbers up to R-et=1000 are explored. Backflow is induced through the merging of large-scale high- and low-speed structures near the wall, and is formed at the tail tip of the low-speed structure. The density and area of backflow structures increase with Reynolds number. The average lifespan of backflow structures is 8 wall units, slightly longer in pipes than channels, and they are convected downstream at an average velocity of approximately 10 wall units, similar to Cardesa et al. (J. Fluid Mech., vol. 880, 2019, R3). Backflow structures can occasionally split, merge, and detach from the wall. Evidence suggests that these phenomena are caused by near-wall structures. Split backflow structures are typically larger and more elongated spanwise due to the shearing of near-wall streaks. Wall-detached backflow structures form when the trailing end of the carrier low-speed structure sits on near-wall high-speed streaks. These structures tend to become wall-attached by approaching the wall, following a similar life cycle as normal backflow structures.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Xi Chen, Katepalli R. Sreenivasan
Summary: This passage discusses the potential exceptions to wall-scaling in turbulent flows, with a focus on the streamwise velocity fluctuation. It introduces a new formula for peak magnitude which approaches a finite limit due to the natural constraint of boundedness on the dissipation rate at the wall, in contrast to the existing logarithmic growth explanation.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Meteorology & Atmospheric Sciences
Line Baserud, Joachim Reuder, Marius O. Jonassen, Timothy A. Bonin, Phillip B. Chilson, Maria A. Jimenez, Pierre Durand
BOUNDARY-LAYER METEOROLOGY
(2020)
Article
Geochemistry & Geophysics
Joan Cuxart, Daniel Martinez-Villagrasa, Ivana Stiperski
ATMOSPHERIC SCIENCE LETTERS
(2020)
Article
Meteorology & Atmospheric Sciences
Jon A. Arrillaga, Pedro Jimenez, Jordi Vila-Guerau de Arellano, Maria A. Jimenez, Carlos Roman-Cascon, Mariano Sastre, Carlos Yague
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2020)
Article
Meteorology & Atmospheric Sciences
Maria A. Jimenez, Antoni Grau, Joan Cuxart
ATMOSPHERIC RESEARCH
(2020)
Article
Meteorology & Atmospheric Sciences
Antoni Grau, Maria A. Jimenez, Joan Cuxart
Summary: The study analyzed the physical mechanisms under sea-breeze conditions in the Palma basin and found that the surface temperature difference is maximal during summer, with sea-breeze events mainly occurring during warm months. The morning reversal strongly depends on large-scale wind speed and direction.
INTERNATIONAL JOURNAL OF CLIMATOLOGY
(2021)
Article
Plant Sciences
Neus Segui, Maria Antonia Jimenez, Joana Cursach
Summary: Local temperature conditions strongly influence seed germination of Hypericum balearicum, with variations in germination rate and timing observed in different environments. The study highlights the importance of considering local temperature effects in understanding plant responses to environmental changes.
Article
Environmental Sciences
Joan Cuxart, Maja Telisman Prtenjak, Blazenka Matjacic
Summary: Under high-pressure systems, the nocturnal atmospheric boundary layer in the Pannonian Basin is influenced by gravity flows generated at the mountain ranges and valleys. Analysis at Zagreb Airport shows how downslope flows from the nearby Medvednica mountain range affect temperature inversion and visibility. These flows can merge with valley flows and converge in the central areas of the basin.
Article
Environmental Sciences
Ana Firanj Sremac, Branislava Lalic, Joan Cuxart, Milena Marcic
Summary: The study found that vegetation primarily affects temperature seasonality, while static factors such as soil texture influence temperature annual variation. The research is limited by missing data and sparse spatial coverage, but alternatives data tested still have their limitations.
Article
Meteorology & Atmospheric Sciences
B. Marti, D. Martinez-Villagrasa, J. Cuxart
Summary: The flux-profile relationships for momentum and sensible heat are assessed over a moderately inhomogeneous complex terrain in the southern pre-Pyrenees. The study found that the classical expressions hold during the daytime, iterative estimations using the Obukhov length and direct estimations using the bulk Richardson number provide similar results, using a second temperature observation can avoid the need for radiometric measurement and the prescription of a thermal roughness length value, and estimations over wet terrain with high irradiance differed significantly from observations.
BOUNDARY-LAYER METEOROLOGY
(2022)
Review
Environmental Sciences
Vicente Garcia-Santos, Juan Manuel Sanchez, Joan Cuxart
Summary: This study reviews the efforts made in the past fifty years to estimate evapotranspiration (ET) using thermal remote sensing data. It discusses the limitations of current ET estimation methods and presents future trends in the field.
Article
Meteorology & Atmospheric Sciences
Jose A. Guijarro, Gemma Simo, Daniel Martinez-Villagrasa, Belen Marti, Maria Antonia Jimenez, Vicens Garcia-Santos, Joan Cuxart
Summary: Measurements in seven sites on the Campus of the University of the Balearic Islands were used to study the impact of surface heterogeneities on extreme daily temperatures. The results showed significant temperature differences between different sites, with maximum differences reaching 1.92 degrees Celsius and minimum differences reaching 2.02 degrees Celsius. The study also found that temperature differences were smaller during the colder months. These findings highlight the potential inhomogeneities in temperature series due to relocation of observation stations.
INTERNATIONAL JOURNAL OF CLIMATOLOGY
(2023)
Article
Biodiversity Conservation
Rafel Beltran, Pedro Beca-Carretero, Nuria Marba, Maria Antonia Jimenez, Anna Traveset
Article
Green & Sustainable Science & Technology
Pedro Santos, Jakob Mann, Nikola Vasiljevic, Elena Cantero, Javier Sanz Rodrigo, Fernando Borbon, Daniel Martinez-Villagrasa, Belen Marti, Joan Cuxart
WIND ENERGY SCIENCE
(2020)
Proceedings Paper
Education & Educational Research
M. A. Jimenez, D. Moranta, J. Torrens, L. Ferrer, J. A. Jurado-Rivera, C. Palomino, A. Borras, R. Santamarta, S. Tejada, A. Sureda, F. Masdeu, M. M. Bibiloni
EDULEARN19: 11TH INTERNATIONAL CONFERENCE ON EDUCATION AND NEW LEARNING TECHNOLOGIES
(2019)
Article
Environmental Sciences
Jon Ander Arrillaga, Carlos Yague, Carlos Roman-Cascon, Mariano Sastre, Maria Antonia Jimenez, Gregorio Maqueda, Jordi Vila-Guerau de Arellano
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2019)
