Article
Multidisciplinary Sciences
Jikun Feng, Huajian Yao, Yi Wang, Piero Poli, Zhu Mao
Summary: This study combines ambient noise interferometry with mineral physics modeling to shed new light on mantle transition zone physics, revealing a localized accumulation of oceanic crust at the bottom of the mantle transition zone. This provides insights into the chemical evolution of Earth and mantle circulation, suggesting complex circulation modes with segregated oceanic crust trapped within the mantle transition zone.
NATURE COMMUNICATIONS
(2021)
Article
Engineering, Mechanical
Jin Chai, Zhan Wang, Emilian I. Parau
Summary: This article considers steady nonlinear flexural-gravity hydraulic falls on the interface of a two-layer density stratified flow past a submerged obstruction on the bottom of a channel. The fluid is assumed to be ideal, and the flow is irrotational. The effect of hydroelasticity is included by modeling the interface as a thin elastic shell with the Cosserat theory. The full Euler equations are numerically solved using boundary integral equation techniques to find steady solutions. New solutions characterized by subcritical flow upstream and different depth ratios are found, and the effects of the aspect ratio of obstruction are investigated. Moreover, solutions with trapped waves and soliton-like forms are sought by introducing a second obstruction downstream and considering small sheet rigidity.
JOURNAL OF FLUIDS AND STRUCTURES
(2023)
Article
Oceanography
Jinghong Wang, Yeqiang Shu, Dongxiao Wang, Qiang Xie, Qiang Wang, Ju Chen, Tingting Zu, Danian Liu, Yunkai He
Summary: This study investigates the deep-current variabilities in the northern South China Sea, finding that TRWs exhibit different spatial distributions in different frequency ranges, influenced by mesoscale perturbations in the upper layer. Longer-period TRWs were observed west of the Dongsha Islands, while bottom current variations on the northeastern South China Sea slope were affected by TRW propagation and local perturbations.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2021)
Article
Physics, Fluids & Plasmas
Z. Wang, J. Chai, E. Parau, C. Page, M. Wang
Summary: This paper considers hydraulic falls on the interface of a two-layer density stratified fluid flow in the presence of bottom topography. By deriving the forced Korteweg-de Vries and modified Korteweg-de Vries equations in different asymptotic limits, the existence and classification of fall solutions are understood. The full Euler equations are then numerically solved using a boundary integral equation method. New solutions characterized by a train of trapped waves are found for interfacial flows past two obstacles. The effects of the relative location, aspect ratio, and convexity-concavity property of the obstacles on interface profiles are also investigated.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Environmental Sciences
Juliana Tavora, Glauber Acunha Goncalves, Elisa Helena Fernandes, Mhd. Suhyb Salama, Daphne van der Wal
Summary: Turbid coastal plumes, carrying sediments, nutrients, and pollutants, pose a challenge in terms of detecting their boundaries. This study compares traditional threshold approaches with a novel algorithm (PLUMES) for detecting turbid coastal plumes from satellite remote sensing. Results show that PLUMES has advantages over thresholds, as it can differentiate different turbidity levels and automatically retrieve metrics of detected plumes. However, PLUMES has only been tested in one study site and needs further application in different areas.
FRONTIERS IN MARINE SCIENCE
(2023)
Article
Oceanography
Henry G. Peterson, Jorn Callies
Summary: The near-bottom mixing in the ocean allows for the upwelling of abyssal waters and affects the flow over midocean ridges. This study extends the commonly used one-dimensional model to capture the spinup and spindown of along-slope flow by considering a two-dimensional approach that includes the effect of Ekman transport and the pressure gradient. The extended model accurately describes the spinup over an idealized ridge and provides a unified framework for understanding the importance of Ekman arrest and spindown in flow along a slope.
JOURNAL OF PHYSICAL OCEANOGRAPHY
(2022)
Article
Mechanics
Nick H. Wise, Gary R. Hunt
Summary: Previous mathematical models of quasi-steady turbulent plumes and fountains have described the flow resulting from a given input of buoyancy. In this study, we take a new perspective by asking what input of buoyancy would result in a plume or fountain with specific characteristics. By developing analytical solutions to the conservation equations, we show that it is possible to design synthetic plumes with desired properties without specifying the buoyancy distribution.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
James Richardson, Gary R. Hunt
Summary: There has been no consensus on the value of the entrainment coefficient alpha for a pure plume. However, after theoretical developments, measurements, and evaluation, it is concluded that alpha = 0.11 +/- 15% should be adopted as the consensus value. This consensus value enhances the application of plume theory and allows for detailed comparison with other turbulent flows.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Oceanography
Hua Zheng, Xiao-Hua Zhu, Juntian Chen, Min Wang, Ruixiang Zhao, Chuanzheng Zhang, Ze-Nan Zhu, Qiang Ren, Yansong Liu, Feng Nan, Fei Yu
Summary: This study analyzes the generation and propagation characteristics of Topographic Rossby waves (TRWs) in the northern Manila Trench (MT) in the South China Sea (SCS) based on observational data. The study finds that TRWs are mainly generated by perturbations caused by the intrusion of the Kuroshio in winter and perturbations generated north of Luzon Island in summer. The study also reveals that variations in the Kuroshio path and related eddies induce TRWs associated with intraseasonal variations in the deep SCS, but the distribution of TRWs is complex due to wave propagation, with some TRWs unrelated to local perturbations but propagating from adjacent regions.
JOURNAL OF PHYSICAL OCEANOGRAPHY
(2022)
Article
Astronomy & Astrophysics
Emily K. Pass, David Charbonneau, Jonathan M. Irwin, Jennifer G. Winters
Summary: Research has found that the spindown of fully convective M dwarfs is strongly dependent on mass, with a slow initial spindown followed by a rapid decrease in rotation periods. However, some stars exhibit significant spindown in the early stages.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Ashfaque Hussain Bokhari, Javlon Rayimbaev, Bobomurat Ahmedov
Summary: The study has obtained exact analytic solutions of Maxwell equations for the magnetic field exterior to a slowly rotating magnetized relativistic star in Einstein-aether gravity, and explored their applications in plasma magnetosphere and unscreened electric field. The effects of Einstein-aether gravity on total energy losses of rotating magnetized relativistic star and the exclusion of certain combinations and ranges of Einstein-aether gravity parameters from pulsar observations have been investigated.
PHYSICS OF THE DARK UNIVERSE
(2021)
Article
Mechanics
Megan K. Richards, Oluwaseun E. Coker, Jose Florido, Rhiannon A. M. Nicholls, Andrew N. Ross, Gabriel G. Rooney
Summary: This study investigates the flow in and around two vertically and horizontally offset plumes. An analytical potential flow model is developed using the Milne-Thomson circle theorem to represent the flow due to adjacent circular and point sources. The predictions of this model are compared against Reynolds-averaged Navier-Stokes simulations and show good agreement, including the location of the stagnation point between the two plumes.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Astronomy & Astrophysics
Shu-Jin Hou, Shuang Du, Tong Liu, Hui-Jun Mu, Ren-Xin Xu
Summary: This paper discusses the possibility of magnetars as the central engines of gamma-ray bursts (GRBs). By analyzing data from the Neil Gehrels Swift GRB, three GRBs with features indicating magnetars as central engines were identified. Magnetars may play a significant role in GRBs, and future multimessenger observations could further validate this hypothesis.
ASTROPHYSICAL JOURNAL
(2021)
Article
Mechanics
Wei Zhang, Bingchuan Nie, Feng Xu
Summary: In this study, experiments and scaling analysis were conducted to investigate the thermal plume on an open cylinder heated from below. The results validate previous numerical findings and present new scaling laws for the rising plume. The study describes the characteristics of the plume at different stages and observes a unique periodic bubbling bifurcation.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Jingzi Huang, Henry C. C. Burridge, Maarten van Reeuwijk
Summary: Using direct numerical simulation, we investigate the mixing processes inside a forced fountain. The fountain has a turbulent/non-turbulent interface with the ambient at the outer boundary. Two turbulent/turbulent internal interfaces are identified within the fountain: (i) the classical boundary between upflow and downflow determined by points of zero mean vertical velocity; and (ii) the streamline separating the mean flow from the entrained fluid emitted by the source and the ambient (the separatrix). Our findings demonstrate that entrainment through turbulent fluxes across the internal boundary is equally important to entrainment by the mean flow. However, entrainment by turbulence behaves differently and cannot be modeled using the same assumptions, posing a challenge for existing models of turbulent fountains and environmental flows inside turbulent environments.
JOURNAL OF FLUID MECHANICS
(2023)
