Latest papers in fluid mechanics

Numerical study of turbulent channel flow perturbed by spanwise topographic heterogeneity: Amplitude and frequency modulation within low- and high-momentum pathways

Physical Review Fluids - Mon, 04/09/2018 - 11:00

Author(s): Ankit Awasthi and William Anderson

The feedback between topographically driven turbulent secondary flows and modulation of small-scale amplitude and frequency is explored. Results demonstrate that modulation remains but differs intrinsically because of background secondary flows within the domain.

[Phys. Rev. Fluids 3, 044602] Published Mon Apr 09, 2018

Impact of a small ellipticity on the sustainability condition of developed turbulence in a precessing spheroid

Physical Review Fluids - Mon, 04/09/2018 - 11:00

Author(s): Yasufumi Horimoto, Gabriel Simonet-Davin, Atsushi Katayama, and Susumu Goto

An experimental investigation shows that the small ellipticity of a precessing spheroidal cavity has a significant impact on the flow transition from solid-body rotational flow to developed turbulence of a confined fluid. In contrast, the developed turbulence in the spheroid is almost identical to that in the sphere.

[Phys. Rev. Fluids 3, 044603] Published Mon Apr 09, 2018

Turbulent thermal superstructures in Rayleigh-Bénard convection

Physical Review Fluids - Fri, 04/06/2018 - 11:00

Author(s): Richard J. A. M. Stevens, Alexander Blass, Xiaojue Zhu, Roberto Verzicco, and Detlef Lohse

Direct numerical simulations of highly turbulent Rayleigh-Bénard convection up to Rayleigh numbers Ra = 109 in horizontally periodic domains with aspect ratios up to Γ = 128, find superstructures of very large-scale and long living coherent structures.

[Phys. Rev. Fluids 3, 041501(R)] Published Fri Apr 06, 2018

Role of Marangoni stress during breakup of surfactant-covered liquid threads: Reduced rates of thinning and microthread cascades

Physical Review Fluids - Fri, 04/06/2018 - 11:00

Author(s): Pritish M. Kamat, Brayden W. Wagoner, Sumeet S. Thete, and Osman A. Basaran

Simulations and experiments resolve a long-standing controversy that the gradient of surface tension—Marangoni stress—rather than surface tension lowering is responsible for decelerated thinning rates and microthread cascades during breakup of surfactant-covered threads.

[Phys. Rev. Fluids 3, 043602] Published Fri Apr 06, 2018

Flapping instability of a liquid jet

Physical Review Fluids - Fri, 04/06/2018 - 11:00

Author(s): Antoine Delon, Alain Cartellier, and Jean-Philippe Matas

We evidence two regimes for the flapping instability of a liquid jet atomized by a gas stream: a first one where it is synchronized with an upstream shear instability, and a second one where frequency is independent of gas flow, simply controlled by the ratio of liquid velocity to liquid jet radius.

[Phys. Rev. Fluids 3, 043901] Published Fri Apr 06, 2018

Particle dynamics and pattern formation in a rotating suspension of positively buoyant particles

Physical Review Fluids - Fri, 04/06/2018 - 11:00

Author(s): Sudarshan Konidena, Jonghoon Lee, K. Anki Reddy, and Anugrah Singh

Buoyant particle suspension in a horizontal rotating cylinder is known to exhibit axially oscillating particle bands in the centrifugal force dominant phase. Numerical simulations using Stokeslets as the particles were performed to investigate the behavior.

[Phys. Rev. Fluids 3, 044301] Published Fri Apr 06, 2018

Impact of dissipation on the energy spectrum of experimental turbulence of gravity surface waves

Physical Review Fluids - Fri, 04/06/2018 - 11:00

Author(s): Antoine Campagne, Roumaissa Hassaini, Ivan Redor, Joël Sommeria, Thomas Valran, Samuel Viboud, and Nicolas Mordant

Experiments are performed in the Coriolis facility to investigate gravity surface wave turbulence. Results indicate that dissipation is responsible for the quantitative discrepancy between experimental and field measurement of the wave energy spectrum, which is systematically steeper in the lab.

[Phys. Rev. Fluids 3, 044801] Published Fri Apr 06, 2018

Nonlinear oscillatory rarefied gas flow inside a rectangular cavity

Physical Review E - Thu, 04/05/2018 - 11:00

Author(s): Peng Wang, Lianhua Zhu, Wei Su, Lei Wu, and Yonghao Zhang

The nonlinear oscillation of rarefied gas flow inside a two-dimensional rectangular cavity is investigated on the basis of the Shakhov kinetic equation. The gas dynamics, heat transfer, and damping force are studied numerically via the discrete unified gas-kinetic scheme for a wide range of paramete...

[Phys. Rev. E 97, 043103] Published Thu Apr 05, 2018

Transient response of nonideal ion-selective microchannel-nanochannel devices

Physical Review E - Thu, 04/05/2018 - 11:00

Author(s): Neta Leibowitz, Jarrod Schiffbauer, Sinwook Park, and Gilad Yossifon

We report evidence of variation in ion selectivity of a fabricated microchannel-nanochannel device resulting in the appearance of a distinct local maximum in the overlimiting chronopotentiometric response. In this system consisting of shallow microchannels joined by a nanochannel, viscous shear at t...

[Phys. Rev. E 97, 043104] Published Thu Apr 05, 2018

Collective dissolution of microbubbles

Physical Review Fluids - Thu, 04/05/2018 - 11:00

Author(s): Sébastien Michelin, Etienne Guérin, and Eric Lauga

Microscopic bubble dissolution is driven by the diffusion of gas within the surrounding liquid. Asymptotic analysis is used to characterize collective shielding effects in bubble lattices, the resulting bubble lifetime and dissolution dynamics.

[Phys. Rev. Fluids 3, 043601] Published Thu Apr 05, 2018

Eddy diffusivity of quasi-neutrally-buoyant inertial particles

Physical Review Fluids - Wed, 04/04/2018 - 11:00

Author(s): Marco Martins Afonso, Paolo Muratore-Ginanneschi, Sílvio M. A. Gama, and Andrea Mazzino

Inertial particles moving in a fluid flow are ubiquitous in nature. Despite their small size, they can actively influence Earth climate dynamics. A new perturbative strategy is proposed to obtain the sedimentation velocity and the effective diffusivity in the limit of neutrally buoyant particles.

[Phys. Rev. Fluids 3, 044501] Published Wed Apr 04, 2018

Generation of intermittent gravitocapillary waves via parametric forcing

Physical Review E - Tue, 04/03/2018 - 11:00

Author(s): Gustavo Castillo and Claudio Falcón

We report on the generation of an intermittent wave field driven by a horizontally moving wave maker interacting with Faraday waves. The spectrum of the local gravitocapillary surface wave fluctuations displays a power law in frequency for a wide range of forcing parameters. We compute the probabili...

[Phys. Rev. E 97, 043101] Published Tue Apr 03, 2018

Reduced-order model for inertial locomotion of a slender swimmer

Physical Review E - Tue, 04/03/2018 - 11:00

Author(s): Raksha Mahalinkam, Felicity Gong, and Aditya S. Khair

The inertial locomotion of an elongated model swimmer in a Newtonian fluid is quantified, wherein self-propulsion is achieved via steady tangential surface treadmilling. The swimmer has a length 2l and a circular cross section of longitudinal profile aR(z), where a is the characteristic width of the...

[Phys. Rev. E 97, 043102] Published Tue Apr 03, 2018

Penetrative convection at high Rayleigh numbers

Physical Review Fluids - Tue, 04/03/2018 - 11:00

Author(s): Srikanth Toppaladoddi and John S. Wettlaufer

Penetrative convection is essential in controlling the dynamics of many geophysical and astrophysical systems. Here, we explore how a nonlinear vertical density profile influences the penetrative convection into a stable stratification.

[Phys. Rev. Fluids 3, 043501] Published Tue Apr 03, 2018

Effect of texture randomization on the slip and interfacial robustness in turbulent flows over superhydrophobic surfaces

Physical Review Fluids - Mon, 04/02/2018 - 11:00

Author(s): Jongmin Seo and Ali Mani

Drag reduction and interfacial robustness of turbulent flows over superhydrophobic surfaces with randomly distributed textures are investigated using direct numerical simulations. Slip length, pressure fluctuations, and interface deformations are analyzed and compared against aligned textures.

[Phys. Rev. Fluids 3, 044601] Published Mon Apr 02, 2018

Electrohydrodynamic coalescence of droplets using an embedded potential flow model

Physical Review E - Fri, 03/30/2018 - 11:00

Author(s): M. Garzon, L. J. Gray, and J. A. Sethian

The coalescence, and subsequent satellite formation, of two inviscid droplets is studied numerically. The initial drops are taken to be of equal and different sizes, and simulations have been carried out with and without the presence of an electrical field. The main computational challenge is the tr...

[Phys. Rev. E 97, 033112] Published Fri Mar 30, 2018

Actuated rheology of magnetic micro-swimmers suspensions: Emergence of motor and brake states

Physical Review Fluids - Fri, 03/30/2018 - 11:00

Author(s): Benoit Vincenti, Carine Douarche, and Eric Clement

We develop a model of elliptical micro-swimmers with a magnetic dipole under shear flow in a dilute suspension subject to a constant magnetic field. We find at finite shear rates transitions to either a motor state in which energy can be extracted or a brake state with high resistance to shear.

[Phys. Rev. Fluids 3, 033302] Published Fri Mar 30, 2018

Effect of a surface tension gradient on the slip flow along a superhydrophobic air-water interface

Physical Review Fluids - Fri, 03/30/2018 - 11:00

Author(s): Dong Song, Baowei Song, Haibao Hu, Xiaosong Du, Peng Du, Chang-Hwan Choi, and Jonathan P. Rothstein

The presence of a surface tension gradient is demonstrated at the air-water interface supported above a millimeter-sized discontinuous groove. It reduces the slip velocity and in some cases results in an interfacial velocity that is opposite to the main flow direction.

[Phys. Rev. Fluids 3, 033303] Published Fri Mar 30, 2018

Structure of wall-bounded flows at transcritical conditions

Physical Review Fluids - Fri, 03/30/2018 - 11:00

Author(s): Peter C. Ma, Xiang I. A. Yang, and Matthias Ihme

Direct numerical simulations of channel flow at transcritical conditions with density change in the flow field are conducted. We find a regime with useful semi-local scaling as well as streamwise velocity and energy spectrum scaling which support the attached eddy model at transcritical conditions.

[Phys. Rev. Fluids 3, 034609] Published Fri Mar 30, 2018

Buoyant miscible displacement flows in a nonuniform Hele-Shaw cell

Physical Review Fluids - Thu, 03/29/2018 - 11:00

Author(s): E. Walling, R. Mollaabbasi, and S. M. Taghavi

By modifying the geometry of a vertical Hele-Shaw cell—making it either converging or diverging—experimental and theoretical investigation shows that it is possible to control the stability of miscible buoyancy driven flows. This includes the promotion/inhibition of viscous fingering.

[Phys. Rev. Fluids 3, 034003] Published Thu Mar 29, 2018


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