Two-dimensional turbulence generated in a finite box produces large-scale coherent vortices coexisting with small-scale fluctuations. We present a rigorous theory explaining the eta=1/4 scaling in the V is proportional to r(-eta) law of the velocity spatial profile within a vortex, where r is the distance from the vortex center. This scaling, consistent with earlier numerical and laboratory measurements, is universal in its independence of details of the small-scale injection of turbulent fluctuations and details of the shape of the box.
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http://dx.doi.org/10.1103/PhysRevE.81.015302 | DOI Listing |
J Acoust Soc Am
December 2024
PIMM Laboratory, UMR 8006, Arts et Metiers Institute of Technology (ENSAM), CNRS, Cnam, 151 boulevard de l'Hôpital, 75013, Paris, France.
During its propagation, a shock wave may come across and interact with different perturbations, including acoustical waves. While this issue has been the subject of many studies, the particular acoustic-acoustic interaction between a weak shock and a sound wave has been very scarcely investigated. Here, a theory describing the encounter of those two waves is developed, up to second- and third-order.
View Article and Find Full Text PDFNanophotonics
November 2024
Laboratory of Information Photonics and Optical Metrology, Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, India.
Singularity in a two-point complex coherence function, known as coherence vortices, represents zero visibility with a helical phase structure. In this paper, we introduce a novel technique to generate the coherence vortices of different topological charges by incoherent source transmittance with exotic structured binary pinholes. The binary pinhole structures have been realized by lithography, followed by wet etching methods.
View Article and Find Full Text PDFSci Rep
November 2024
Univ. Grenoble Alpes, CNRS, Grenoble INP, LEGI, 38000, Grenoble, France.
The most prominent and persistent feature of the eastern Mediterranean Levantine Basin (LB) is the warm anticyclonic Cyprus Eddy (CE) located above the Eratosthenes Seamount (ESM). This eddy periodically couples with two smaller cyclonic and anticyclonic eddies, the South Shikmona Eddy (SSE) and North Shikmona Eddy (NSE), which form downstream. The reason for the zonal drift of the CE center and the formation mechanism of the CE, SSE and NSE is largely debated today, yet the upwelling and biological productivity of the LB can be strongly impacted by the local dynamics.
View Article and Find Full Text PDFSoft Matter
December 2024
Departament de Ciència de Materials i Química Física, Universitat de Barcelona, Barcelona, Spain.
Comput Biol Med
January 2025
Center for Digital Cardiovascular Innovations, Cardiovascular Division, Miller School of Medicine, Miami, FL, USA. Electronic address:
Objective: This study aims to investigate the micro-hemodynamic effects of strut malapposition in patient-specific stented coronary bifurcations.
Methods: Using the mapping-back technique, three-dimensional reconstructions of clinical post-stenting artery bifurcations with strut malapposition were accurately generated from optical coherence tomography scans of 9 patients. Computational fluid dynamics (CFD) simulations were then conducted with these models to examine the impact of strut malapposition on various fluid dynamic parameters, including flow patterns, vorticity, strain rates, viscosity, and wall shear stress (WSS).
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