Physical Review Fluids

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Updated: 15 hours 42 min ago

Evaporation-driven solutocapillary flow of thin liquid films over curved substrates

Wed, 03/13/2019 - 10:00

Author(s): Mariana Rodríguez-Hakim, Joseph M. Barakat, Xingyi Shi, Eric S. G. Shaqfeh, and Gerald G. Fuller

Evaporation of a volatile solvent induces solutocapillary Marangoni flows by creating gradients in species concentration and surface tension. These flows are experimentally and theoretically investigated in sub-micron films at dilute solute concentrations where Van der Waals effects are important.

[Phys. Rev. Fluids 4, 034002] Published Wed Mar 13, 2019

Instabilities of nonisothermal nanocatalytic reactive flows in porous media

Wed, 03/13/2019 - 10:00

Author(s): B. Dastvareh and J. Azaiez

Chemo-hydrodynamic instabilities are investigated in the presence of nano-catalysts. The additional transport mechanism of nano-catalysts as a result of the heat of reaction, called thermophoresis, has affected both the dynamics and the amount of chemical products.

[Phys. Rev. Fluids 4, 034003] Published Wed Mar 13, 2019

Measurements on a yawed rotor blade pitching in reverse flow

Tue, 03/12/2019 - 10:00

Author(s): Luke R. Smith and Anya R. Jones

Vortex shedding patterns are examined on a yawed wing pitching in reverse flow. The yawed wing exhibits suppression of its secondary flow structures compared to an unyawed wing. Various physical mechanisms, particularly spanwise flow, are evaluated to explain the shedding pattern of the yawed wing.

[Phys. Rev. Fluids 4, 034703] Published Tue Mar 12, 2019

Wall slip regimes in jammed suspensions of soft microgels

Mon, 03/11/2019 - 10:00

Author(s): Justin Péméja, Baudouin Géraud, Catherine Barentin, and Marie Le Merrer

The slip velocity of jammed polymer microgels is measured as the wall stress is increased by 4 orders of magnitude. The friction law exhibits a transition in slip regimes, from a nonlinear to a linear scaling, linked to two distinct dissipation mechanisms at the scale of the soft elements.

[Phys. Rev. Fluids 4, 033301] Published Mon Mar 11, 2019

Enhanced and suppressed multiscale dispersion of bidisperse inertial particles due to gravity

Mon, 03/11/2019 - 10:00

Author(s): Rohit Dhariwal and Andrew D. Bragg

Direct numerical simulations are used to study the relative dispersion of settling, bidisperse inertial particles in isotropic turbulence. It is found that gravity can significantly enhance the relative dispersion, not only in the direction parallel, but even in the direction normal to gravity.

[Phys. Rev. Fluids 4, 034302] Published Mon Mar 11, 2019

Transition from convection rolls to large-scale cellular structures in turbulent Rayleigh-Bénard convection in a liquid metal layer

Fri, 03/08/2019 - 10:00

Author(s): Megumi Akashi, Takatoshi Yanagisawa, Yuji Tasaka, Tobias Vogt, Yuichi Murai, and Sven Eckert

A new coherent structure appears on turbulent Rayleigh-Bénard convection in a liquid metal layer; transitions to large-scale cellular structures from oscillatory roll structures occur with Rayleigh numbers. A scaling law describing characteristic length of the structures is suggested.

[Phys. Rev. Fluids 4, 033501] Published Fri Mar 08, 2019

Evaluation of potential flow models for unsteady separated flow with respect to experimental data

Fri, 03/08/2019 - 10:00

Author(s): Field Manar and Anya R. Jones

Wake characteristics and force production of a flat plate wing starting from rest at high incidence are examined. Circulation production at the wing leading edge is shown to be coupled to wing kinematics and the wake state. Several potential flow models are compared to experiments.

[Phys. Rev. Fluids 4, 034702] Published Fri Mar 08, 2019

Velocity probability distribution scaling in wall-bounded flows at high Reynolds numbers

Thu, 03/07/2019 - 10:00

Author(s): M.-W. Ge, Xiang I. A. Yang, and Ivan Marusic

A study on the scaling implications of the attached eddy hypothesis and the large deviation theory on the velocity probability distribution function (PDF) concludes that, when scaled properly, the remote tails of the streamwise and spanwise velocity PDF collapse for flows in the logarithmic layer.

[Phys. Rev. Fluids 4, 034101] Published Thu Mar 07, 2019

Trapped vorticity for controlled modification of an airfoil's aerodynamic loads

Thu, 03/07/2019 - 10:00

Author(s): Daniel P. Brzozowski, Bojan Vukasinovic, and Ari Glezer

Static and transient responses of an airfoil to bi-directional flow control actuation at the trailing-edge are investigated in wind tunnel experiments. Flow field measurements elucidate control of aerodynamic loads through regulation of trapped vorticity concentrations upstream of the trailing edge.

[Phys. Rev. Fluids 4, 034601] Published Thu Mar 07, 2019

Flow force measurements and the wake transition in purely inline vortex-induced vibration of a circular cylinder

Thu, 03/07/2019 - 10:00

Author(s): Tyler D. Gurian, Todd Currier, and Yahya Modarres-Sadeghi

We find a novel shedding mode (Alternating-Symmetric) in the vortex-induced vibration response of a cylinder free to oscillate in the inline direction. In this mode, two vortices of opposite sign are shed simultaneously from two sides of the oscillating cylinder, but their sizes alternate per cycle.

[Phys. Rev. Fluids 4, 034701] Published Thu Mar 07, 2019

Electric field induced droplet deformation and breakup in confined shear flows

Wed, 03/06/2019 - 10:00

Author(s): Rattandeep Singh, Supreet Singh Bahga, and Amit Gupta

Deformation or breakup of a droplet suspended in confined shear flows and subjected to an electric field is investigated numerically. A contrasting behavior of the droplet depending upon the electrical properties of the fluids is reported.

[Phys. Rev. Fluids 4, 033701] Published Wed Mar 06, 2019

Instability of precession driven Kelvin modes: Evidence of a detuning effect

Wed, 03/06/2019 - 10:00

Author(s): Johann Herault, André Giesecke, Thomas Gundrum, and Frank Stefani

Experiments in a precessing cylinder filled with water show signatures of azimuthally drifting inertial waves. These modes originate from a triadic resonance and their characteristic frequency dependence is explained by a detuning mechanism due to the slowdown of the background flow.

[Phys. Rev. Fluids 4, 033901] Published Wed Mar 06, 2019

Transport of flexible fibers in confined microchannels

Tue, 03/05/2019 - 10:00

Author(s): Jean Cappello, Mathias Bechert, Camille Duprat, Olivia du Roure, François Gallaire, and Anke Lindner

The deformation of a flexible fiber transported perpendicularly in a plug flow in a confining microchannel is studied using experiments and numerical simulations. The fiber deflection, resulting from an inhomogeneous force distribution, is a function of an elastoviscous number and fiber confinement.

[Phys. Rev. Fluids 4, 034202] Published Tue Mar 05, 2019

Orientation dynamics of nonspherical particles under surface gravity waves

Tue, 03/05/2019 - 10:00

Author(s): Michelle H. DiBenedetto, Jeffrey R. Koseff, and Nicholas T. Ouellette

Nonspherical particles in the ocean are relevant to phenomena such as microplastics, plankton and sediment. Experimental results of the orientation dynamics of nonspherical particles in waves find competition between the waves and the inertial effects on particle orientation.

[Phys. Rev. Fluids 4, 034301] Published Tue Mar 05, 2019

Linear and nonlinear regimes of an inertial wave attractor

Tue, 03/05/2019 - 10:00

Author(s): Maxime Brunet, Thierry Dauxois, and Pierre-Philippe Cortet

We report an experimental study of the nonlinear regime of an inertial wave attractor revealing the emergence of a triadic resonance instability with singular features. The attractor properties are shown to be well described by introducing a turbulent viscosity in the linear attractor model.

[Phys. Rev. Fluids 4, 034801] Published Tue Mar 05, 2019

Excitation and resonant enhancement of axisymmetric internal wave modes

Tue, 03/05/2019 - 10:00

Author(s): S. Boury, T. Peacock, and P. Odier

Inspired by geophysical phenomena, such as storm generated internal waves in the ocean, an experimental study is performed using an axisymmetric internal wave generator. Radial and vertical confinement lead to Bessel-shaped standing waves and resonance effects caused by multiple cavity reflections.

[Phys. Rev. Fluids 4, 034802] Published Tue Mar 05, 2019

Effects of trailing edge shape on vortex formation by pitching panels of small aspect ratio

Mon, 03/04/2019 - 10:00

Author(s): Arman Hemmati, Tyler Van Buren, and Alexander J. Smits

A study examines wake dynamics for oscillating foils with different trailing edges and relates them to unsteady propulsive performance of the foil. It also connects the main wake features to surface pressure fluctuations on both faces of the foil during an oscillatory period.

[Phys. Rev. Fluids 4, 033101] Published Mon Mar 04, 2019

Vibration-induced thermal instabilities in supercritical fluids in the absence of gravity

Mon, 03/04/2019 - 10:00

Author(s): Deewakar Sharma, Arnaud Erriguible, Gurunath Gandikota, Daniel Beysens, and Sakir Amiroudine

Supercritical fluids when subjected to vibrations in the direction parallel and normal to the interface lead to Rayleigh-vibrational and parametric instabilities. These instabilities arise in the thermal boundary layer as a result of strong thermomechanical coupling.

[Phys. Rev. Fluids 4, 033401] Published Mon Mar 04, 2019

Thermocapillary and electrohydrodynamic effects on the stability of dynamic contact lines

Mon, 03/04/2019 - 10:00

Author(s): Devin T. Conroy, Leonardo Espín, Omar K. Matar, and Satish Kumar

Electric fields and temperature fields significantly modify the stability of dynamic contact lines. Electric fields enhance the growth of transverse perturbations, whereas temperature fields can enhance or suppress growth depending on the direction of the temperature gradient.

[Phys. Rev. Fluids 4, 034001] Published Mon Mar 04, 2019

Steady flow regimes and mixing performance in arrow-shaped micro-mixers

Mon, 03/04/2019 - 10:00

Author(s): A. Mariotti, C. Galletti, E. Brunazzi, and M. V. Salvetti

The steady flow regimes and mixing performances of arrow-like micro-mixers are investigated experimentally and by DNS for varying Re and tilting angles. Arrow-mixers trigger mixing at lower Re than for T-mixers, but for large tilting angles mixing does not increase monotonically with Re.

[Phys. Rev. Fluids 4, 034201] Published Mon Mar 04, 2019