We provide an observation suggesting a strong correlation between helicity and enstrophy in fluid turbulence. Helicity statistics were obtained in a direct numerical simulation of forced isotropic turbulence. An investigation of coherent structures revealed that intermittently large local helicity was found in the core region of the coherent rotational structures, thus showing a strong correlation with local enstrophy, not dissipation. Statistics regarding the relative helicity and the correlation between velocity and vorticity conditioned on different levels of enstrophy clearly suggest that velocity and vorticity tend to be aligned in the core of the coherent structures.
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http://dx.doi.org/10.1103/PhysRevE.80.017301 | DOI Listing |
Membranes (Basel)
January 2025
Environmental Science and Engineering Program, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
Reverse osmosis (RO) filtration performance is heavily influenced by the design of the feed spacer. Spacer design impacts hydrodynamic patterns within the system, affecting water production and concentration polarization. Two spacer designs, namely pillar (P) and standard (S), were investigated to improve the performance of a commercially available spacer design (C) in the RO process.
View Article and Find Full Text PDFFront Cardiovasc Med
January 2025
Pediatric Cardiology, Pediatric Heart Center, Skåne University Hospital, Lund, Sweden.
Background: Recurrent coarctation of the aorta (re-CoA) is a well-known although not fully understood complication after surgical repair, typically occurring in 10%-20% of cases within months after discharge.
Objectives: To (1) characterize geometry of the aortic arch and blood flow from pre-discharge magnetic resonance imaging (MRI) in neonates after CoA repair; and (2) compare these measures between patients that developed re-CoA within 12 months after repair and patients who did not.
Methods: Neonates needing CoA repair, without associated major congenital heart defects, were included.
Comput Biol Med
January 2025
UCL Mechanical Engineering, University College London, UK; Ri.MED Foundation, Palermo, Italy; University of Palermo, Department of Engineering, Palermo, Italy. Electronic address:
Aortic valve replacements, both surgical and transcatheter, are nowadays widely employed treatments. Although clinically effective, these procedures are correlated with potentially severe clinical complications which can be associated with the non-physiological haemodynamics that they establish. In this work, the fluid dynamics changes produced by surgical and transcatheter aortic valve replacements are analysed and compared with an ideal healthy native valve configuration, employing advanced fluid-structure interaction (FSI) simulations.
View Article and Find Full Text PDFLangmuir
January 2025
Department of Chemical Engineering, Indian Institute of Technology, Guwahati 781039, Assam, India.
Self-organized contact line instabilities (CLI) of a macroscopic liquid crystal (LC) droplet can be an ingenious pathway to generate a large collection of miniaturized LC drops. For example, when a larger drop of volatile solvent (e.g.
View Article and Find Full Text PDFUltrason Sonochem
January 2025
School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China; MOE Key Laboratory of Cryogenic Technology and Equipment, Xi'an Jiaotong University, Xi'an 710049, China.
Cavitation plays a crucial role in the reliability of components in refrigeration systems. The properties of refrigerants change significantly with temperature, thereby amplifying the impact of thermodynamic effects. This study, based on the Large Eddy Simulation (LES) method and the Schnerr-Sauer (S-S) cavitation model, investigates the transient cavitating flow characteristics of the R134a refrigerant in a Venturi tube (VT).
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