Latest papers in fluid mechanics

Effect of shear thinning on superhydrophobic slip: Perturbative corrections to the effective slip length

Physical Review Fluids - Wed, 12/06/2017 - 10:00

Author(s): Darren Crowdy

We find expressions for the change in hydrodynamic slip length when a weakly shear-thinning fluid flows longitudinally, or transversely, over a periodic array of flat, unidirectional no-shear slots from a modified reciprocal theorem of Stokes flow and exact solutions for a Newtonian fluid.

[Phys. Rev. Fluids 2, 124201] Published Wed Dec 06, 2017

Emergent scar lines in chaotic advection of passive directors

Physical Review Fluids - Wed, 12/06/2017 - 10:00

Author(s): Bardia Hejazi, Bernhard Mehlig, and Greg A. Voth

When fibers are advected in a fluid flow, they organize into patterns dominated by scar lines across which the fiber orientation rotates by π. An exploration of the topology of the fiber orientation field in a 2D chaotic flow shows that scar lines form by a process of fluid stretching reversal.

[Phys. Rev. Fluids 2, 124501] Published Wed Dec 06, 2017

Dynamics of nonspherical microbubble oscillations above instability threshold

Physical Review E - Tue, 12/05/2017 - 10:00

Author(s): Matthieu Guédra, Sarah Cleve, Cyril Mauger, Philippe Blanc-Benon, and Claude Inserra

Time-resolved dynamics of nonspherical oscillations of micrometer-sized bubbles are captured and analyzed using high-speed imaging. The axisymmetry of the bubble shape is ensured with certainty for the first time from the recordings of two synchronous high-speed cameras located at 90∘. The temporal ...

[Phys. Rev. E 96, 063104] Published Tue Dec 05, 2017

Giant deviation of a relaxation time from generalized Newtonian theory in discontinuous shear thickening suspensions

Physical Review Fluids - Tue, 12/05/2017 - 10:00

Author(s): Rijan Maharjan and Eric Brown

Experimental study on discontinuous shear thickening fluids reveals that the relaxation times agree with a generalized Newtonian model for lower weight fractions. At high weight fractions, however, the relaxation times disagree by up to 4 orders of magnitude.

[Phys. Rev. Fluids 2, 123301] Published Tue Dec 05, 2017

Numerical study of two disks settling in an Oldroyd-B fluid: From periodic interaction to chaining

Physical Review E - Mon, 12/04/2017 - 10:00

Author(s): Tsorng-Whay Pan and Roland Glowinski

In this article, we present a numerical study of the dynamics of two disks sedimenting in a narrow vertical channel filled with an Oldroyd-B fluid. Two kinds of particle dynamics are observed: (i) a periodic interaction between the two disks, and (ii) the formation of a two-disk chain. For the perio...

[Phys. Rev. E 96, 063103] Published Mon Dec 04, 2017

Coalescence-induced droplet jumping on superhydrophobic surfaces: Effects of droplet mismatch

Physical Review Fluids - Mon, 12/04/2017 - 10:00

Author(s): Joram Wasserfall, Patric Figueiredo, Reinhold Kneer, Wilko Rohlfs, and Philipp Pischke

Superhydrophobic surfaces are designated by a low wettability that gives rise to self-cleaning. This study analyses the fluid dynamics of self-propelled droplet jumping upon binary unequal sized droplet coalescence with three-dimensional simulations.

[Phys. Rev. Fluids 2, 123601] Published Mon Dec 04, 2017

Observation of structural universality in disordered systems using bulk diffusion measurement

Physical Review E - Fri, 12/01/2017 - 10:00

Author(s): Antonios Papaioannou, Dmitry S. Novikov, Els Fieremans, and Gregory S. Boutis

We report on an experimental observation of classical diffusion distinguishing between structural universality classes of disordered systems in one dimension. Samples of hyperuniform and short-range disorder were designed, characterized by the statistics of the placement of micrometer-thin parallel ...

[Phys. Rev. E 96, 061101(R)] Published Fri Dec 01, 2017

Logarithmic scaling for fluctuations of a scalar concentration in wall turbulence

Physical Review E - Fri, 12/01/2017 - 10:00

Author(s): Hideaki Mouri, Takeshi Morinaga, Toshimasa Yagi, and Kazuyasu Mori

Within wall turbulence, there is a sublayer where the mean velocity and the variance of velocity fluctuations vary logarithmically with the height from the wall. This logarithmic scaling is also known for the mean concentration of a passive scalar. By using heat as such a scalar in a laboratory expe...

[Phys. Rev. E 96, 063101] Published Fri Dec 01, 2017

Cooling beyond the boundary value in supercritical fluids under vibration

Physical Review E - Fri, 12/01/2017 - 10:00

Author(s): D. Sharma, A. Erriguible, and S. Amiroudine

Supercritical fluids when subjected to simultaneous quench and vibration have been known to cause various intriguing flow phenomena and instabilities depending on the relative direction of temperature gradient and vibration. Here we describe a surprising and interesting phenomenon wherein temperatur...

[Phys. Rev. E 96, 063102] Published Fri Dec 01, 2017

Experimental study of turbulent-jet wave packets and their acoustic efficiency

Physical Review Fluids - Fri, 12/01/2017 - 10:00

Author(s): David E. S. Breakey, Peter Jordan, André V. G. Cavalieri, Petrônio A. Nogueira, Olivier Léon, Tim Colonius, and Daniel Rodríguez

Pressure fluctuations in unforced subsonic jets indicate the presence of linear wave packets in the near field. An interpretation in the resolvent framework shows that these signatures represent higher order near-field behavior that must be captured to obtain accurate far-field acoustic predictions.

[Phys. Rev. Fluids 2, 124601] Published Fri Dec 01, 2017

Exact relations for energy transfer in self-gravitating isothermal turbulence

Physical Review E - Thu, 11/30/2017 - 10:00

Author(s): Supratik Banerjee and Alexei G. Kritsuk

Self-gravitating isothermal supersonic turbulence is analyzed in the asymptotic limit of large Reynolds numbers. Based on the inviscid invariance of total energy, an exact relation is derived for homogeneous (not necessarily isotropic) turbulence. A modified definition for the two-point energy corre...

[Phys. Rev. E 96, 053116] Published Thu Nov 30, 2017

Continuity waves in resolved-particle simulations of fluidized beds

Physical Review Fluids - Thu, 11/30/2017 - 10:00

Author(s): Daniel P. Willen, Adam J. Sierakowski, Gedi Zhou, and Andrea Prosperetti

A method to coarse-grain the results of resolved simulations is described and used to demonstrate the presence of continuity waves in the simulations of 500–2000 particles suspended in an upward fluid flow. The results agree very well with the standard continuum theory of kinematic waves.

[Phys. Rev. Fluids 2, 114305] Published Thu Nov 30, 2017

Analysis of anisotropically permeable surfaces for turbulent drag reduction

Physical Review Fluids - Thu, 11/30/2017 - 10:00

Author(s): Nabil Abderrahaman-Elena and Ricardo García-Mayoral

Anisotropic permeable surfaces are proposed to reduce turbulent skin friction. The apparent streamwise slip induced reduces drag, while the spanwise one increases it. Transpiration can trigger the appearance of Kelvin-Helmholtz-like rollers, which limit the performance of the surface.

[Phys. Rev. Fluids 2, 114609] Published Thu Nov 30, 2017

Point force singularities outside a drop covered with an incompressible surfactant: Image systems and their applications

Physical Review Fluids - Wed, 11/29/2017 - 10:00

Author(s): Vaseem A. Shaik and Arezoo M. Ardekani

Image systems for Stokes flow singularities outside a drop covered with an incompressible surfactant are derived. They are used in finding the mobility matrix for two surfactant-laden drops of arbitrary sizes and the velocity of a microorganism outside a surfactant-covered drop.

[Phys. Rev. Fluids 2, 113606] Published Wed Nov 29, 2017

Vortex-ring-induced internal mixing upon the coalescence of initially stationary droplets

Physical Review Fluids - Wed, 11/29/2017 - 10:00

Author(s): Xi Xia, Chengming He, Dehai Yu, Jiaquan Zhao, and Peng Zhang

The formation of the mushroomlike jet emerging after droplet coalescence is deciphered by studying the growth and detachment of the main vortex ring. A Reynolds number calculated based on the main vortex ring is shown to provide a unified formation criterion for such internal jets.

[Phys. Rev. Fluids 2, 113607] Published Wed Nov 29, 2017

Jets and large-scale vortices in rotating Rayleigh-Bénard convection

Physical Review Fluids - Tue, 11/28/2017 - 10:00

Author(s): Céline Guervilly and David W. Hughes

Large-scale features in rotating convection can take the form of either jets or coherent vortices. Numerical simulations of horizontally anisotropic planar rotating convection reveal the interaction between jets and vortices and show how these typically co-exist.

[Phys. Rev. Fluids 2, 113503] Published Tue Nov 28, 2017

Deceleration of one-dimensional mixing by discontinuous mappings

Physical Review E - Mon, 11/27/2017 - 10:00

Author(s): Hannah Kreczak, Rob Sturman, and Mark C. T. Wilson

We present a computational study of a simple one-dimensional map with dynamics composed of stretching, permutations of equally sized cells, and diffusion. We observe that the combination of the aforementioned dynamics results in eigenmodes with long-time exponential decay rates. The decay rate of th...

[Phys. Rev. E 96, 053112] Published Mon Nov 27, 2017

Kinetic-contact-driven gigantic energy transfer in a two-dimensional Lennard-Jones fluid confined to a rotating pore

Physical Review E - Mon, 11/27/2017 - 10:00

Author(s): Paweł Karbowniczek and Agnieszka Chrzanowska

A two-dimensional Lennard-Jones system in a circular and rotating container has been studied by means of molecular dynamics technique. A nonequilibrium transition to the rotating stage has been detected in a delayed time since an instant switching of the frame rotation. This transition is attributed...

[Phys. Rev. E 96, 053113] Published Mon Nov 27, 2017

Role of red cells and plasma composition on blood sessile droplet evaporation

Physical Review E - Mon, 11/27/2017 - 10:00

Author(s): Luca Lanotte, Didier Laux, Benoît Charlot, and Manouk Abkarian

The morphology of dried blood droplets derives from the deposition of red cells, the main components of their solute phase. Up to now, evaporation-induced convective flows were supposed to be at the base of red cell distribution in blood samples. Here, we present a direct visualization by videomicro...

[Phys. Rev. E 96, 053114] Published Mon Nov 27, 2017

Nonlinear and subharmonic stability analysis in film-driven morphological patterns

Physical Review E - Mon, 11/27/2017 - 10:00

Author(s): Matteo Bernard Bertagni and Carlo Camporeale

The interaction of a gravity-driven water film with an evolving solid substrate (calcite or ice) results in the formation of fascinating wavy patterns similar both in caves and in ice-falls. Due to their remarkable similarity, we adopt a unified approach in the study of pattern formation of longitud...

[Phys. Rev. E 96, 053115] Published Mon Nov 27, 2017


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