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Recent work has developed a nonlinear hydrodynamic fluctuation theory for a chain of coupled anharmonic oscillators governing the conserved fields, namely, stretch, momentum, and energy. The linear theory yields two propagating sound modes and one diffusing heat mode, all three with diffusive broadening. In contrast, the nonlinear theory predicts that, at long times, the sound mode correlations satisfy Kardar-Parisi-Zhang scaling, while the heat mode correlations have Lévy-walk scaling. In the present contribution we report on molecular dynamics simulations of Fermi-Pasta-Ulam chains to compute various spatiotemporal correlation functions and compare them with the predictions of the theory. We obtain very good agreement in many cases, but also some deviations.
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http://dx.doi.org/10.1103/PhysRevE.90.012124 | DOI Listing |
Bioinspir Biomim
September 2025
Mechanical Engineering, University of California Berkeley, 6177 Etcheverry Hall, Berkeley, California, 94720, UNITED STATES.
Riblets inspired by natural shark skin denticles are widely recognized for their drag-reducing performance. Although previous research has predominantly focused on two-dimensional riblet geometries, three-dimensional topographies remain underexplored due to the complex architecture of denticle-inspired surfaces. Natural riblet arrays, comprising thousands of interconnected denticles, pose challenges in terms of parameterization, simulation, and fabrication.
View Article and Find Full Text PDFSci Rep
August 2025
Division of Computer Science and Engineering, Louisiana State University, Baton Rouge, LA, 70803, USA.
Daily fluctuations in coastal hypoxia significantly impact marine ecosystems, requiring forecasts that balance efficiency and accuracy. Statistical models are computationally efficient but often fall short in prediction performance, while mechanistic models are accurate yet resource-intensive. Here, we present a lightweight artificial intelligence (AI) model for daily hypoxia forecasting on the Louisiana-Texas shelf, trained and validated using a 14-year mechanistic ROMS hindcast.
View Article and Find Full Text PDFBiomimetics (Basel)
August 2025
State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation, Tianjin University, Tianjin 300354, China.
Harbor seals, equipped with their uniquely structured whiskers, demonstrate remarkable proficiency in tracking the trajectories of prey within dark and turbid marine environments. This study experimentally investigates the wake-induced vibrations of an elastically supported whisker model placed in the wakes of circular, square, and equilateral triangular cylinders of varying dimensions. Thereafter, a machine learning model is trained to identify and classify these intrinsic responses.
View Article and Find Full Text PDFPhys Rev Lett
August 2025
Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany.
The high-temperature plasma in the solar interior generates stochastic gravitational waves (GWs). Owing to its significance as the primary source of high-frequency GWs in the Solar System, we reexamine this phenomenon by highlighting some physical processes, including the contribution of macroscopic hydrodynamic fluctuations. Our analysis builds upon several studies of axion emission from the Sun, particularly in relation to the treatment of plasma effects.
View Article and Find Full Text PDFEnviron Sci Technol
August 2025
State Key Laboratory of Lake and Watershed Science for Water Security, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
Organic phosphorus (OP), a major phosphorus pool in sediments, can be converted into bioavailable phosphate. Although biological activity is considered the primary driver of OP dephosphorylation, the abiotic mechanism under redox oscillations remains unexplained. Here, we show that hydrological perturbation-driven redox fluctuations can mediate abiotic phosphate release from OP.
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