Latest papers in fluid mechanics

Author(s): Joel Koplik

A recent claim that a liquid drop sliding on a solid has a transition from static to sliding friction, based on an ingenious but indirect experiment, disagrees with molecular dynamics simulations which directly measure the forces involved.

[Phys. Rev. Fluids 4, 014001] Published Wed Jan 09, 2019

Author(s): Shenfei Liao, Wenbin Zhang, Hu Chen, Liyong Zou, Jinhong Liu, and Xianxu Zheng

The evolution of a uniform interface subjected to a perturbed shock wave has been experimentally studied over a range of Atwood numbers 0.22≤A≤0.68 and Mach numbers 1.2≤M≤1.8 using a vertical shock tube. The perturbed shock wave is produced by diffracting a planar incident shock over a rigid cylinde...

[Phys. Rev. E 99, 013103] Published Tue Jan 08, 2019

Author(s): Romain Fiévet, Venkat Raman, Stephen Voelkel, and Philip L. Varghese

To understand the coupling between mixing and vibrational relaxation, a novel state-specific model is solved inside a direct numerical simulation of a compressible jet. It is found that gas compressibility effects trigger vibrational nonequilibrium, while turbulence affects the states’ population.

[Phys. Rev. Fluids 4, 013401] Published Tue Jan 08, 2019

Author(s): Ya Gai, Alison Bick, and Sindy K. Y. Tang

The timescale of droplet rearrangement in a 2D concentrated emulsion—a microfluidic crystal—displays 3 regimes with 2 transitions with increasing capillary number. The loss of order in the crystal flow corresponds to the second transition involving a solid to liquid-like transition of the emulsion.

[Phys. Rev. Fluids 4, 014201] Published Tue Jan 08, 2019

Author(s): David W. Martin, Tamunotubo George, and François Blanchette

A computational study of clean drops rising into a layer of dissolved surfactant, modeling oil drops rising in the ocean, is presented. Drops are first accelerated by surface tension gradients before being slowed by accumulated surfactants on their surface.

[Phys. Rev. Fluids 4, 014302] Published Tue Jan 08, 2019

Author(s): Leander Michels, Yves Méheust, Mario A. S. Altoé, Éverton C. dos Santos, Henrik Hemmen, Roosevelt Droppa, Jr., Jon O. Fossum, and Geraldo J. da Silva

The transport of chemical species in porous media is ubiquitous in subsurface processes, including contaminant transport, soil drying, and soil remediation. We study vapor transport in a multiscale porosity material, a smectite clay, in which water molecules travel in mesopores and macropores betwee...

[Phys. Rev. E 99, 013102] Published Mon Jan 07, 2019

[Phys. Rev. Fluids 4, 010001] Published Mon Jan 07, 2019

Author(s): Bruce R. Sutherland, Ulrich Achatz, Colm-cille P. Caulfield, and Jody M. Klymak

How does energy input at planetary scales in the atmosphere and ocean ultimately reach scales small enough to be dissipated efficiently through turbulence? Here we describe advances in understanding the underlying instability and transport processes achieved through observations, theory, and numerical simulations, with a focus inspired in part by a February 2018 interdisciplinary workshop on the subject held at the Banff International Research Station.

[Phys. Rev. Fluids 4, 010501] Published Mon Jan 07, 2019

Author(s): Pierre Lecointre, Timothée Mouterde, Antonio Checco, Charles T. Black, Atikur Rahman, Christophe Clanet, and David Quéré

Droplets merging on hydrophobic nanocones jump off, and the takeoff speed is found to be maximum at microscale, below and above which viscosity and inertia, respectively, cap this speed. Microdroplets successively experience strong lift off, slow flight, and smooth landing, which impedes bouncing.

[Phys. Rev. Fluids 4, 013601] Published Mon Jan 07, 2019

Author(s): Mairi E. McKay, Arjun Berera, and Richard D. J. G. Ho

We explore the effect of the magnetic Prandtl number Pm on energy and dissipation in fully resolved direct numerical simulations of steady-state, mechanically forced, homogeneous magnetohydrodynamic turbulence in the range 1/32<Pm<32. We compare the spectra and show that if the simulations are...

[Phys. Rev. E 99, 013101] Published Fri Jan 04, 2019

Author(s): Panayiota Katsamba and Eric Lauga

Bacteriophage viruses infect and replicate within bacteria. Some phages ride along the flagellar filaments used by bacteria for propulsion. Here we confirm a 40-year old hypothesis and show that infection can be induced by hydrodynamic forces due to rotation of flagellar filaments.

[Phys. Rev. Fluids 4, 013101] Published Fri Jan 04, 2019

Author(s): Lei Fang, Sanjeeva Balasuriya, and Nicholas T. Ouellette

Starting from the notion that a coherent structure is a set of fluid elements with very similar behavior, the idea of linear neighborhoods is introduced. These kinematic structures also play a role in the flow dynamics, in that the spectral energy transfer inside them is higher than it is outside.

[Phys. Rev. Fluids 4, 014501] Published Fri Jan 04, 2019

Author(s): Qian Li, Weihua Cai, Feng-Chen Li, Bingxi Li, and Ching-Yao Chen

We numerically evaluate permeable heterogeneity effects on gravity-driven miscible porous media flows relevant to underground CO2 storage. For typical finger widths below correlation length we find largest variation measures among random realizations, and lowest mean due to the resonant effect.

[Phys. Rev. Fluids 4, 014502] Published Fri Jan 04, 2019

Author(s): Guillaume Michel

While at least four plane surface gravity waves are required to make a resonant interaction, only three modes are required in a cylindrical container. An experiment is carried out to isolate and characterize such a triad interaction.

[Phys. Rev. Fluids 4, 012801(R)] Published Wed Jan 02, 2019

Author(s): J. J. J. Gillissen and H. J. Wilson

We theoretically predict, that, in sphere suspensions, hydrodynamic interaction forces produce a negligible first normal stress difference, while contact forces produce a positive first normal stress difference.

[Phys. Rev. Fluids 4, 013301] Published Wed Jan 02, 2019

Author(s): Thibault Chastel and Anne Mongruel

High-frequency laser interferometry is used to resolve the motion of an immersed sphere prior to its collision with a wetted textured wall below the bouncing transition. The measurements reveal different sphere dynamics resulting from the texture-induced modification of the lubrication drag force.

[Phys. Rev. Fluids 4, 014301] Published Wed Jan 02, 2019

Author(s): Keisuke Nakayama, Takahiro Sato, Kenji Shimizu, and Leon Boegman

This study proposes a classification for breaker types when internal solitary waves shoal over a uniform slope. We use an extended data set of extant published experimental data and our own numerical experiments. We find that a single index delineates collapsing and plunging breakers.

[Phys. Rev. Fluids 4, 014801] Published Wed Jan 02, 2019

Author(s): Jocelyn Dunstan, Kyoung J. Lee, Yongyun Hwang, Simon F. Park, and Raymond E. Goldstein

Suspensions of bioluminiscent bacteria display convective motions reminiscent of classical bioconvection, but this poses a conundrum, as these organisms lack flagella-driven motility under the conditions studied. Instead, evaporation of the salty growth medium is found to drive the convection.

[Phys. Rev. Fluids 3, 123102] Published Fri Dec 28, 2018

Author(s): Pedro H. A. Anjos, Eduardo O. Dias, and José A. Miranda

Weakly nonlinear analysis is used to study fingering instabilities in radially tapered (converging and diverging) Hele-Shaw cells. It is found that changes in the capillary number modify the interface instability behavior and the finger shapes relative to what usually occurs in parallel-plate cells.

[Phys. Rev. Fluids 3, 124004] Published Fri Dec 28, 2018

Author(s): Juwon Jang and Changhoon Lee

Neutrally buoyant finite-size particles laden in stratified turbulent channel flows are found to enhance internal gravity waves, thus blocking heat transfer. In the near-wall region, these particles are preferentially located in the high-speed streaks.

[Phys. Rev. Fluids 3, 124309] Published Fri Dec 28, 2018