Article
Mechanics
Qianhao Xiao, Boyan Jiang, Xiaopei Yang, Yanyan Ding, Jun Wang
Summary: This study uses large eddy simulation to analyze the turbulent flows in a squirrel cage fan, and establishes an intelligent reduced-order model. The study provides new insights into flow control strategies in fan engineering.
Article
Engineering, Marine
Maelys Magnier, Yanis Saouli, Benoit Gaurier, Philippe Druault, Gregory Germain
Summary: This paper experimentally investigates the effects of regular waves propagating against the current on the wake of a wide bathymetric obstacle. It is found that the presence of waves strongly modifies cylinder wake, affecting vortex generation and wake development.
Article
Mechanics
Xiao Hu, Jianzhong Lin, Yu Guo, Xiaoke Ku
Summary: The inertial focusing of elliptical particles and the formation of self-organizing trains in a channel flow are studied using the lattice Boltzmann method. Different particle characteristics such as aspect ratio, concentration, Reynolds number, and blockage ratio affect the formation and stability of the particle trains.
Article
Mechanics
Amir. A. A. Beige, Amir Mardani
Summary: This work conducted large eddy simulations of a Gas Turbine Model Combustor (GTMC) using a five-step global mechanism that accounts for separate thermal and non-thermal NOx formation. The accuracy of the solution was verified by comparing time-averaged profiles of flow variables and fluctuations to experimental and numerical data. The results revealed the strong connection between vortical structures, temperature field, and chemical reactions within the chamber, with vortices playing a crucial role in premixing and NOx reduction, but also contributing to NOx generation through the formation of high temperature spots containing chemical radicals. The importance of baroclinic torque in vorticity creation was demonstrated by comparing its values to vortex stretching in upstream regions of the chamber.
Article
Environmental Sciences
Johannes Rohrs, Trygve Halsne, Graig Sutherland, Knut-Frode Dagestad, Lars Robert Hole, Goran Brostrom, Kai H. H. Christensen
Summary: Surface currents and turbulent mixing during a near-inertial wave (NIW) were observed using an accoustic doppler current profiler (ADCP) and satellite-tracked drifters. Drifter trajectories showed characteristics of an Ekman solution superposed with the NIW at three depth levels. Velocity and dissipation estimates from the ADCP revealed strong shear and a distinct constant flux layer between the roughness length and a critical depth at 4m. A shear free slab layer performing an inertial oscillation was observed below. Dissipation, estimated from the ADCP's vertical beam, peaked in the wave-enhanced friction layer when the current opposed the wind and wave direction. Maximum turbulence was observed below the constant flux layer when the NIW was in a phase opposite to the time-averaged current, causing rapid realignment of currents at various depths in the entire boundary layer.
FRONTIERS IN MARINE SCIENCE
(2023)
Article
Optics
A. V. Falits, V. V. Kuskov, V. A. Banakh
Summary: The study experimentally examines the propagation of vortex optical beams through artificial convective turbulence. It is found that as the refractive turbulence intensifies, the intensity distribution of vortex beams becomes speckled and the initial ring structure distorts and disappears. The average intensity distribution gradually blurs and becomes close to a Gaussian distribution with a maximum intensity at the center of the beam. The comparison between vortex beams with increasing and unchanged initial transverse sizes shows that the random displacements of the vortex beam's energy centroid are independent of the topological charge.
JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER
(2023)
Article
Multidisciplinary Sciences
Lia Siegelman, William R. Young, Andrew P. Ingersoll
Summary: Vortex crystals are structures formed by like-signed vortices in solid-body rotation, embedded in a background of weaker vorticity. It has been discovered that these crystals can form from the free evolution of randomly excited two-dimensional turbulence on an idealized polar cap, and they exhibit long-lasting stability.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Mechanics
Bajrang Sharma, Rishita Das, Sharath S. Girimaji
Summary: The study adapts and extends the local streamline topology classification method to describe the geometry of infinitesimal vortex lines. Analysis of DNS data reveals a self-similar bell shape in the joint probability density function of vorticity gradient tensor invariants, suggesting universality in turbulent flows. The research also examines vortex reconnection and finds consistent local topology and geometry of the reconnection bridge in different initial configurations. Overall, the topological characterization of the vorticity field provides a useful analytical basis for studying vorticity dynamics in turbulence and other fluid flows.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Optics
Zhoulin Ding, Yongji Yu, Xiaoqing Li, Siyao Li, Chunyu Hou
Summary: We introduce a new family of autofocusing waves called autofocusing Bessel beams (ABBs). These beams have potential applications in medical laser treatment and optical tweezers. Through the angular spectrum method, ABBs are proven to be a class solution for the Helmholtz equation, with easily adjustable focal length. The study also observes the autofocusing of ABBs and the dual focus phenomenon when ABBs pass through a focusing lens. This article provides a theoretical model and experimental protocol for studying abruptly autofocusing waves.
Article
Mechanics
Xinran Zhao, Zongxin Yu, Jean-Baptiste Chapelier, Carlo Scalo
Summary: This paper investigates the pre- and post-reconnection dynamics of a trefoil knotted vortex, finding that the self-advection velocity before reconnection scales with inviscid parameters and reconnection occurs earlier and more rapidly at higher Reynolds numbers. The vortex propagation velocities after reconnection are affected by viscous effects, with the larger vortex ring carrying most of the helicity and enstrophy. The total helicity dissipation rate agrees reasonably well between large-eddy simulations and direct numerical simulations, with vortex centerline helicity and vortex-tube-integrated helicity being less sensitive to the reconnection process.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Cheolgyun Jung, Minho Song, Daegyoum Kim
Summary: This study investigates the formation of a starting jet through a novel eversion process using a vortex generator model. By varying geometric and kinematic parameters, such as the length and bending rigidity of the everting sheets, the study examines their effects on the deformation of the sheets and the formation of the jet. The interaction between the starting jet and the everting sheets enables a faster jet with an improved hydrodynamic impulse to be developed within a shorter stroke time.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Optics
Jia-Lu Zhu, Ren-Chao Jin, Li-Li Tang, Zheng-Gao Dong, Jia-Qi Li, Jin Wang
Summary: This paper theoretically proposes and numerically demonstrates a dual-focusing effect with a cylindrical vector-light characteristic using an all-silicon metalens. The polarization dependence allows for the interchange of focused radial and azimuthal vector beams by orthogonally switching the polarization of incident light. The unique contributions of these vector beams to longitudinal and transverse optical forces on glass spheres are demonstrated, and the compactness of the all-silicon metalens makes it promising for multidimensional optical trapping applications.
PHOTONICS RESEARCH
(2022)
Article
Mechanics
Farid Aligolzadeh, Markus Holzner, James R. Dawson
Summary: The interaction between small-scale vortical structures and the surrounding fluid is investigated using experimental and numerical data. The flow across the boundary of vortex structures is examined, and a non-Gaussian distribution of entrainment velocity is observed. The enstrophy transport equation is analyzed to quantify the inviscid and viscous components of the entrainment/detrainment process. The study also compares the findings with the Burgers vortex model.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Materials Science, Multidisciplinary
Yan Qin, Huajun Yang, Ping Jiang, Weinan Caiyang, Miaofang Zhou, Biao Cao
Summary: This paper investigates the transmission characteristics of Bessel-Gaussian (BG) beams in free space and turbulent atmosphere after passing through a Cassegrain antenna system. The results suggest that the half-cone angles of the beam and optical system parameters can control the propagation trajectory and cross-talk among different orbital angular momentum (OAM) modes of the BG beam. The focused BG beam has a potential to reduce cross-talk among different OAM modes at the receiver plane compared to non-focused beams.
RESULTS IN PHYSICS
(2021)
Article
Optics
Zhong Min, Li Jiu-sheng
Summary: This study proposes a notched concave metasurface that can generate multifunctional vortex beams and adapt to different polarizations. The designed metasurface has potential applications in flexible manipulation of orbital angular momentum and polarization detection of terahertz waves in future terahertz wireless communications.
OPTICS COMMUNICATIONS
(2022)
Article
Environmental Sciences
Steven J. Kaptein, Matias Duran-Matute, Federico Roman, Vincenzo Armenio, Herman J. H. Clercx
ENVIRONMENTAL FLUID MECHANICS
(2019)
Article
Mechanics
Ying Zhu, C. Cambon, F. S. Godeferd, A. Salhi
JOURNAL OF FLUID MECHANICS
(2019)
Editorial Material
Environmental Sciences
Benoit Cushman-Roisin, Matias Duran Matute, Leon Kamp, GertJan van Heijst
ENVIRONMENTAL FLUID MECHANICS
(2019)
Article
Engineering, Mechanical
A. S. Gonzalez-Vera, T. J. S. Wilting, A. P. C. Holten, G. J. F. van Heijst, M. Duran-Matute
EXPERIMENTS IN FLUIDS
(2020)
Article
Engineering, Civil
Steven J. Kaptein, Matias Duran-Matute, Federico Roman, Vincenzo Armenio, Herman J. H. Clercx
JOURNAL OF HYDRAULIC RESEARCH
(2020)
Article
Oceanography
Steven J. Kaptein, Koen J. van de Wal, Leon P. J. Kamp, Vincenzo Armenio, Herman J. H. Clercx, Matias Duran-Matute
Article
Environmental Sciences
Henri Lam, Alexandre Delache, Fabien S. Godeferd
Article
Geosciences, Multidisciplinary
Alfredo Samuel Gonzalez-Vera, GertJan van Heijst, Matias Duran-Matute
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2020)
Article
Mechanics
H. Lam, A. Delache, F. S. Godeferd
Summary: The study focuses on the strong stratification regime of stably stratified turbulence and the viscosity-affected stratified state, decomposing the three-dimensional velocity-density fields into internal gravity waves (IGWs) and eddy motion. Separate evolution equations for IGWs and eddies are established. At Re-b around 1, a significant exchange of energy from IGWs to eddies is observed, while for Re-b > 1, the dynamics of IGWs and eddies appear to be separate with no global energy exchange. The mixing due to eddies is found to be four times greater than that due to waves at the largest Re-b considered.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Biophysics
Jerome Jansen, Xavier Escriva, Fabien Godeferd, Patrick Feugier
Summary: This study presents a computational multiscale bio-chemo-mechanical model for intimal hyperplasia and investigates the interactions between hemodynamics, cellular dynamics, and biochemistry in the development of this pathology. A tractable modeling framework is proposed through coupling hypothesis among time and space scales. Experimental results at short and long timescales show qualitative and quantitative consistency with the model predictions.
BIOMECHANICS AND MODELING IN MECHANOBIOLOGY
(2022)
Article
Mechanics
J. Liu, M. Oberlack, Y. Wang, A. Delache, F. S. Godeferd
Summary: This study presents a theory of inertial wave focusing generated by a vertically oscillating slender torus immersed in a uniformly rotating fluid. The results show that the wave rays form a double cone symmetric about the plane on which the torus is located, and the waves focus at the two vertices of the double cone. The focusing effect becomes weaker with increasing friction effects.
Article
Biophysics
Jerome Jansen, Xavier Escriva, Fabien Godeferd, Patrick Feugier
Summary: We use in silico experiments to study the role of hemodynamics and the type of disendothelization on intimal hyperplasia. Applying a multiscale bio-chemo-mechanical model on an idealized artery, we observed the development of lesions initially at the site of damage and later displaced downstream, regardless of the type of damage. The model's sensitivity to pathology-protective and pathology-promoting zones is consistent with experimental findings, demonstrating the central role of damage shape and local wall shear stresses on the dynamics of the lesion.
BIOMECHANICS AND MODELING IN MECHANOBIOLOGY
(2023)
Article
Physics, Fluids & Plasmas
Andrea Maffioli, Alexandre Delache, Fabien S. Godeferd
PHYSICAL REVIEW FLUIDS
(2020)
Article
Physics, Fluids & Plasmas
Giovanni Viciconte, Benoit-Joseph Grea, Fabien S. Godeferd, Philippe Arnault, Jean Clerouin
Article
Physics, Fluids & Plasmas
M. Duran-Matute, D. van Gorp, G. J. F. van Heijst
