Latest papers in fluid mechanics
Numerical investigation of the coupling of vibrational nonequilibrium and turbulent mixing using state-specific description
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
Timescale and spatial distribution of local plastic events in a two-dimensional microfluidic crystal
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
Water vapor diffusive transport in a smectite clay: Cationic control of normal versus anomalous diffusion
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
Announcement: PRFluids Publishes Invited Perspective on Modeling Imbalances in the Atmosphere and Ocean
[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
Fully resolved array of simulations investigating the influence of the magnetic Prandtl number on magnetohydrodynamic turbulence
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
Miscible density-driven flows in heterogeneous porous media: Influences of correlation length and distribution of permeability
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
Fingering instability transition in radially tapered Hele-Shaw cells: Insights at the onset of nonlinear effects
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
Modification of turbulence and stratification of stably stratified turbulent channel flows by finite-size particles
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
Author(s): Mahmoud Sadek and Hussein Aluie
Can you gain “insight” by relinquishing some of your sight? Indeed, we show how to quantify the energy content of various structures in a flow by observing it through “eyeglasses” of varying strength. We also introduce a new class of “lenses” with a simple design which yield more accurate results.
[Phys. Rev. Fluids 3, 124610] Published Fri Dec 28, 2018
Author(s): Christian R. Scullard and Bruce A. Buffett
One of the most intriguing features of Earth's axial magnetic dipole field, well known from the geological record, is its occasional and unpredictable reversal of polarity. Understanding the phenomenon is rendered very difficult by the highly nonlinear nature of the underlying magnetohydrodynamic pr...
[Phys. Rev. E 98, 063112] Published Thu Dec 27, 2018