Physical Review Fluids
Author(s): A. R. Koblitz, S. Lovett, and N. Nikiforakis
Two-dimensional numerical simulations of a suspension of sedimenting particles in a Bingham fluid find three possible regimes: all, a fraction, and none of the particles sedimenting.
[Phys. Rev. Fluids 3, 093302] Published Mon Sep 24, 2018
Author(s): Yun Chen, Frank Malambri, and Sungyon Lee
Viscous fingering arises as air invades a draining viscous suspension. Experiments show that suspended particles delay the onset of fingering but also accelerate its growth rate. In addition, particles of select sizes are observed to coat the channel surfaces and not drain.
[Phys. Rev. Fluids 3, 094001] Published Mon Sep 24, 2018
Author(s): Roumaissa Hassaini and Nicolas Mordant
The effect of confinement in a high-aspect-ratio channel on the statistical properties of weak turbulence of gravity-capillary waves at the surface of water is investigated. Discreteness due to confinement coexists with an almost one-dimensional kinetic sort of wave turbulence.
[Phys. Rev. Fluids 3, 094805] Published Mon Sep 24, 2018
Author(s): Pejman Sanaei and Linda J. Cummings
An idealized first-principles model describing filtration of a feed solution containing small particles in a microstructured porous membrane is presented. Optimal configurations for the pore microstructure are identified in terms of maximizing throughput of filtered fluid and filter lifetime.
[Phys. Rev. Fluids 3, 094305] Published Fri Sep 21, 2018
Author(s): Simon J. Haward, Jacob Page, Tamer A. Zaki, and Amy Q. Shen
Experimental evidence is presented for the existence of critical layers in inertioelastic shear flows over wavy surfaces, where theory predicts amplification of the spanwise vorticity.
[Phys. Rev. Fluids 3, 091302(R)] Published Fri Sep 21, 2018
Scaling laws of top jet drop size and speed from bubble bursting including gravity and inviscid limit
Author(s): Alfonso M. Gañán-Calvo
Scaling laws are proposed for the size and the velocity of the droplet which is ejected when a bubble rises to a free surface and bursts. These new scalings consistently incorporate the effect of gravity and the limit of negligible viscosity of the liquid.
[Phys. Rev. Fluids 3, 091601(R)] Published Thu Sep 20, 2018
Author(s): Sidharth GS, Anubhav Dwivedi, Graham V. Candler, and Joseph W. Nichols
An investigation shows that laminar supersonic flow on a 2D compression corner can destabilize to become 3D beyond a critical turn angle. This compressible instability resides in the recirculating flow, producing spiral wall flow patterns postseparation and wall temperature streaks downstream.
[Phys. Rev. Fluids 3, 093901] Published Wed Sep 19, 2018
Turbulent/nonturbulent interfaces in high-resolution direct numerical simulation of temporally evolving compressible turbulent boundary layers
Author(s): Xinxian Zhang, Tomoaki Watanabe, and Koji Nagata
Turbulent-nonturbulent interfaces are studied in temporally evolving subsonic and supersonic turbulent boundary layers by comparing the results of direct numerical simulations with the entrainment model based on a single vortex and the theory for spatially evolving boundary layers.
[Phys. Rev. Fluids 3, 094605] Published Tue Sep 18, 2018
Author(s): Fengjian Jiang, Bjørnar Pettersen, Helge I. Andersson, Jongmin Kim, and Sungtae Kim
The wake behind a concave, curved cylinder configuration is investigated at different Reynolds numbers. Distinctly different wake flow regimes were observed in the computed flow field, including oblique vortex shedding and dislocations. The crucial influence of a straight vertical extension is explored.
[Phys. Rev. Fluids 3, 094804] Published Tue Sep 18, 2018
Author(s): Fan Zhang, Arnaud Erriguible, Théo Gavoille, Michaël T. Timko, and Samuel Marre
Inertial breakup modes are identified at microscale for co-flowing jets using a high-pressure mixer.
[Phys. Rev. Fluids 3, 092201(R)] Published Mon Sep 17, 2018
Author(s): William A. Sirignano
A normal compressive shock with upstream pressure from 10 to 500 bar is analyzed for density, enthalpy, entropy, and velocity with nitrogen, oxygen, argon, and carbon dioxide. New descriptions for sound speed, Prandtl’s relation, the Rankine-Hugoniot relation, and Riemann invariants are presented.
[Phys. Rev. Fluids 3, 093401] Published Mon Sep 17, 2018
Author(s): L. Biferale, G. Boffetta, A. A. Mailybaev, and A. Scagliarini
Three-dimensional direct numerical simulations of Rayleigh-Taylor turbulence with various initial unstable temperature distributions finds a modified self-similar mixing in the long term.
[Phys. Rev. Fluids 3, 092601(R)] Published Wed Sep 12, 2018
Author(s): Carole Planchette, Sylvain Petit, Hannes Hinterbichler, and Günter Brenn
The collisions of a drop stream with an immiscible jet are experimentally studied revealing the formation of several complex structures classified in four main regimes. When neither the drops nor the jet fragment,“drops in jet” are observed that could be hardened to produce advanced fibers.
[Phys. Rev. Fluids 3, 093603] Published Wed Sep 12, 2018
Author(s): Tobias Baier, Sudarshan Tiwari, Samir Shrestha, Axel Klar, and Steffen Hardt
At large Knudsen numbers a Janus particle in a thermal gradient shows a preferred orientation. The interplay between rotational diffusion and thermophoretic motion is investigated.
[Phys. Rev. Fluids 3, 094202] Published Wed Sep 12, 2018
Author(s): Scott Strednak, Saif Shaikh, Jason E. Butler, and Élisabeth Guazzelli
Fibers in suspension migrate towards the center of the pipe where they are more aligned with the flow. The migration depends on the fraction of the volume of the suspension swept out by the rotating fibers.
[Phys. Rev. Fluids 3, 091301(R)] Published Mon Sep 10, 2018
Author(s): S. Boury, B. Thiria, R. Godoy-Diana, G. Artana, J. E. Wesfreid, and J. D'Adamo
The Stuart-Landau reduced order model is tested with experimental data from the wake of a cylinder wake forced by plasma actuators, finding an important role played by the changing mean flow.
[Phys. Rev. Fluids 3, 091901(R)] Published Mon Sep 10, 2018
Entrainment model for fully-developed wind farms: Effects of atmospheric stability and an ideal limit for wind farm performance
Author(s): Paolo Luzzatto-Fegiz and Colm-cille P. Caulfield
A new model of wind farm aerodynamics establishes an upper bound for power density, which is an order of magnitude larger than achieved by contemporary turbine arrays. The model also provides a one-equation prediction for the output of existing wind farms, and can include atmospheric stability.
[Phys. Rev. Fluids 3, 093802] Published Mon Sep 10, 2018
Author(s): Ryan P. Jones, Austin B. Isner, Hongyi Xiao, Julio M. Ottino, Paul B. Umbanhowar, and Richard M. Lueptow
Particles differing in size or density segregate in dense granular flows. In bidisperse mixtures, the sinking (small or heavy) species concentration that maximizes the segregation flux is <50% and decreases with increasing size or density ratio, matching a classic kinetic-sieving model.
[Phys. Rev. Fluids 3, 094304] Published Mon Sep 10, 2018
Extremes, intermittency, and time directionality of atmospheric turbulence at the crossover from production to inertial scales
Author(s): E. Zorzetto, A. D. Bragg, and G. Katul
A study of how the interplay between mechanical and buoyant production of turbulent kinetic energy affects fully developed atmospheric turbulent flows finds impacts both on the frequency of extreme scalar fluctuations and on the time-directional properties of scalar Eulerian measurements.
[Phys. Rev. Fluids 3, 094604] Published Mon Sep 10, 2018
Author(s): Diego Berzi and James T. Jenkins
We propose corrections to the kinetic theory for fluidity in granular flows near random close packing, in order to take account of anisotropy and increases in granular temperature.
[Phys. Rev. Fluids 3, 094303] Published Fri Sep 07, 2018