We report that many exact invariant solutions of the Navier-Stokes equations for both pipe and channel flows are well represented by just a few modes of the model of McKeon and Sharma [J. Fluid Mech. 658, 336 (2010)]. This model provides modes that act as a basis to decompose the velocity field, ordered by their amplitude of response to forcing arising from the interaction between scales. The model was originally derived from the Navier-Stokes equations to represent turbulent flows and has been used to explain coherent structure and to predict turbulent statistics. This establishes a surprising new link between the two distinct approaches to understanding turbulence.
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http://dx.doi.org/10.1103/PhysRevE.93.021102 | DOI Listing |
J Appl Crystallogr
January 2024
Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Flow cells are ubiquitous in laboratories and automated instrumentation, and are crucial for ease of sample preparation, analyte addition and buffer exchange. The assumption that the fluids have exchanged completely in a flow cell is often critical to data interpretation. This article describes the buoyancy effects on the exchange of fluids with differing densities or viscosities in thin, circular flow cells.
View Article and Find Full Text PDFCommun Math Phys
April 2024
Department of Mathematics, Tulane University, New Orleans, LA 70118 USA.
We prove that all Galerkin truncations of the 2d stochastic Navier-Stokes equations in vorticity form on any rectangular torus subjected to hypoelliptic, additive stochastic forcing are chaotic at sufficiently small viscosity, provided the frequency truncation satisfies . By "chaotic" we mean having a strictly positive Lyapunov exponent, i.e.
View Article and Find Full Text PDFChaos
December 2024
Euromed University of Fés (UEMF Fés), BiomedTech Engineering School, 30000 Fés, Morocco.
This paper presents a survey and critical analysis of the mathematical literature on modeling of dynamic populations living in a fluid medium. The present review paper is divided into two main parts: The first part deals with the multiscale derivation of deterministic and stochastic cross-diffusion systems governed by the incompressible Navier-Stokes equations. The derivation is obtained from the underlying description at the microscopic scale in kinetic theory models according to the micro-macro decomposition method.
View Article and Find Full Text PDFSci Rep
December 2024
Department of electrical engineering, college of engineering, King Saud University, Riyadh, 11421, Saudi Arabia.
Plain flaps (PFs) significantly increase camber, enhancing lift and aerodynamic performance when deployed. In Darrieus Vertical Axis Wind Turbines (VAWTs), which perform efficiently in low-speed, turbulent wind conditions, structural modifications like PFs can improve efficiency. This study explores plain flaps with 10-20-degree deflections at different chord lengths to enhance the NACA 2412 aerofoil's performance.
View Article and Find Full Text PDFComput Biol Med
January 2025
Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai-400076, India.
Investigating magnetic blood flow characteristics through arteries and micron-size channels for clinical therapies in biomedicine is becoming increasingly important with the rise of point-of-care diagnostics devices. A computational fluid dynamics (CFD) investigation is conducted to explore blood flow within a coronary artery affected by an elliptical stenosis near the artery wall under the influence of a magnetic field. The novelty of our study is the integration of Navier-Stokes and Maxwell's equations to calculate body forces on fluid flow, coupled with the application of magnetic fields both longitudinally and vertically, and the use of the Carreau-Yasuda model to analyse non-Newtonian blood rheology.
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