Latest papers in fluid mechanics

Spontaneous instability in internal solitary-like waves

Physical Review Fluids - Thu, 01/17/2019 - 10:00

Author(s): Chengzhu Xu, Marek Stastna, and David Deepwell

The onset and growth of shear instability in internal solitary waves is studied. It is found that there are cases in which the instability occurs spontaneously, cases in which its onset is Reynolds-number dependent, and cases in which it must be triggered by externally imposed noise.


[Phys. Rev. Fluids 4, 014805] Published Thu Jan 17, 2019

Effect of motility on the transport of bacteria populations through a porous medium

Physical Review Fluids - Wed, 01/16/2019 - 10:00

Author(s): Adama Creppy, Eric Clément, Carine Douarche, Maria Veronica D'Angelo, and Harold Auradou

An experimental study of the effects of bacterial motility on its transport in a porous medium is presented. For flow velocity that can exceed 10 times the swimming velocity, the transport is found to be strongly retarded by the particle-grain hydrodynamic interaction. This is not observed in nonmotile bacteria.


[Phys. Rev. Fluids 4, 013102] Published Wed Jan 16, 2019

Impact of turbulence on flying insects in tethered and free flight: High-resolution numerical experiments

Physical Review Fluids - Wed, 01/16/2019 - 10:00

Author(s): Thomas Engels, Dmitry Kolomenskiy, Kai Schneider, Marie Farge, Fritz-Olaf Lehmann, and Jörn Sesterhenn

We perform high resolution numerical simulations of a bumblebee interacting with a turbulent inflow for both tethered and free flight. We find that average aerodynamical forces, moments, and power do not vary with turbulent intensity, but their fluctuations grow as turbulent intensity increases.


[Phys. Rev. Fluids 4, 013103] Published Wed Jan 16, 2019

Effect of Mach number and volume fraction in air-shock interacting with a bed of randomly distributed spherical particles

Physical Review Fluids - Tue, 01/15/2019 - 10:00

Author(s): Y. Mehta, K. Salari, T. L. Jackson, and S. Balachandar

Shock interaction with a bed of randomly distributed particles leads to large variation in the drag forces, highlighting the impact of neighboring particles, and indicating a need for point-particle force models that account for this drag variation.


[Phys. Rev. Fluids 4, 014303] Published Tue Jan 15, 2019

Damping of surface waves by floating particles

Physical Review Fluids - Tue, 01/15/2019 - 10:00

Author(s): Bruce R. Sutherland and Neil J. Balmforth

Surface waves in the presence of floating particles are shown to arrest in finite-time as a consequence of dissipation associated with flow between the particles; implications for wave damping by sea ice are discussed.


[Phys. Rev. Fluids 4, 014804] Published Tue Jan 15, 2019

Microscopic determination of macroscopic boundary conditions in Newtonian liquids

Physical Review E - Mon, 01/14/2019 - 10:00

Author(s): Hiroyoshi Nakano and Shin-ichi Sasa

We study boundary conditions applied to the macroscopic dynamics of Newtonian liquids from the view of microscopic particle systems. We assume the existence of microscopic boundary conditions that are uniquely determined from a microscopic description of the fluid and the wall. By using molecular dy...


[Phys. Rev. E 99, 013106] Published Mon Jan 14, 2019

Time evolution equation for advective heat transport as a constraint for optimal bounds in Rayleigh-Bénard convection

Physical Review Fluids - Mon, 01/14/2019 - 10:00

Author(s): A. Tilgner

Upper bounds on quantities of interest in Rayleigh-Bénard convection are derived by including a constraint derived from the time evolution equation for advective heat transport. This additional constraint leads to improved bounds on the toroidal dissipation.


[Phys. Rev. Fluids 4, 014601] Published Mon Jan 14, 2019

Influence of spanwise rotation and scalar boundary conditions on passive scalar transport in turbulent channel flow

Physical Review Fluids - Mon, 01/14/2019 - 10:00

Author(s): Geert Brethouwer

Direct numerical simulations of passive scalar transport in turbulent channel flow subject to spanwise rotation are performed with two different scalar boundary conditions. A key finding is that rotation strongly reduces the turbulent Prandtl number, irrespective of the scalar boundary conditions.


[Phys. Rev. Fluids 4, 014602] Published Mon Jan 14, 2019

Numerical simulations of the shear instability and subsequent degeneration of basin scale internal standing waves

Physical Review Fluids - Mon, 01/14/2019 - 10:00

Author(s): Andrew Grace, Marek Stastna, and Francis J. Poulin

High resolution numerical simulations of the evolution and subsequent degeneration of large amplitude internal standing waves are presented. Emphasized are examples of large amplitude wave train formation coexisting with shear instability.


[Phys. Rev. Fluids 4, 014802] Published Mon Jan 14, 2019

Internal gravity waves generated by an impulsive plume

Physical Review Fluids - Mon, 01/14/2019 - 10:00

Author(s): Alan Brandt and Kara R. Shipley

Laboratory experiments demonstrate the generation of internal waves by a short-duration impulsive plume. After the plume descends to a maximum depth, it rebounds to an equilibrium level where the ensuing oscillation results in the generation of a propagating internal wave field.


[Phys. Rev. Fluids 4, 014803] Published Mon Jan 14, 2019

Reduced-order modeling of fully turbulent buoyancy-driven flows using the Green's function method

Physical Review Fluids - Fri, 01/11/2019 - 10:00

Author(s): M. A. Khodkar, Pedram Hassanzadeh, Saleh Nabi, and Piyush Grover

A novel method for reduced-order modeling of turbulent flows is discussed in the context of fully turbulent Rayleigh-Bénard convection. The method can be used to control the turbulent mean profiles, to discern the spectral properties of turbulent flows, and to improve the data-driven techniques.


[Phys. Rev. Fluids 4, 013801] Published Fri Jan 11, 2019

Stability analysis for a thermodynamically consistent model of relativistic fluid dynamics

Physical Review E - Thu, 01/10/2019 - 10:00

Author(s): Laura Stricker and Hans Christian Öttinger

In relativistic fluid mechanics, positive entropy production is known to be insufficient for guaranteeing stability. Much stronger criteria for thermodynamic admissibility have become available in nonequilibrium thermodynamics. We here perform a linear stability analysis for a model of relativistic ...


[Phys. Rev. E 99, 013105] Published Thu Jan 10, 2019

Breakup of a particulate suspension jet

Physical Review Fluids - Thu, 01/10/2019 - 10:00

Author(s): J. Château and H. Lhuissier

A falling jet of a concentrated suspension is found to break abruptly where its diameter becomes a few particles thick. A simple model explains the jet breakup length observed experimentally.


[Phys. Rev. Fluids 4, 012001(R)] Published Thu Jan 10, 2019

Stall of airfoils with blunt noses at low to moderately high Reynolds numbers

Physical Review Fluids - Thu, 01/10/2019 - 10:00

Author(s): Matthew G. Kraljic and Zvi Rusak

The onset of leading-edge stall on stationary, smooth, thin, two-dimensional airfoils with blunter than classical nose shapes at low to moderately high Reynolds number flows is studied. Global stall is delayed to higher angles of attack as nose bluntness is increased.


[Phys. Rev. Fluids 4, 014101] Published Thu Jan 10, 2019

Influence of inlet flow profiles on swirling flow dynamics in a finite-length pipe

Physical Review Fluids - Thu, 01/10/2019 - 10:00

Author(s): Yuxin Zhang, Zvi Rusak, and Shixiao Wang

The influence of various inlet swirling flow profiles on the manifold of steady axisymmetric states of flows, their domain of attraction, and on flow dynamics in a straight, long circular pipe is investigated.


[Phys. Rev. Fluids 4, 014701] Published Thu Jan 10, 2019

Modeling of Rayleigh-Taylor mixing using single-fluid models

Physical Review E - Wed, 01/09/2019 - 10:00

Author(s): Ioannis W. Kokkinakis, Dimitris Drikakis, and David L. Youngs

Turbulence mixing models of different degree of complexity are investigated for Rayleigh-Taylor mixing flows with reference to high-resolution implicit large eddy simulations. The models considered, in order of increasing complexity, comprise the (i) two-equation K-L, (ii) three-equation K-L-a, (iii...


[Phys. Rev. E 99, 013104] Published Wed Jan 09, 2019

Explosive Leidenfrost droplets

Physical Review Fluids - Wed, 01/09/2019 - 10:00

Author(s): Florian Moreau, Pierre Colinet, and Stéphane Dorbolo

Experiments show that Leidenfrost droplets made of water and surfactant undergo a violent explosion. This unexpected behavior is triggered by the formation of a shell during the evaporation. Shortly afterwards, the temperature increases above the boiling point, leading to bubble growth, shell stretching, and explosion.


[Phys. Rev. Fluids 4, 013602] Published Wed Jan 09, 2019

Quantifying hydrodynamic collective states of magnetic colloidal spinners and rollers

Physical Review Fluids - Wed, 01/09/2019 - 10:00

Author(s): Y. Wang, S. Canic, G. Kokot, A. Snezhko, and I. S. Aranson

This work expands the scope of modern computational tools for predictive modeling of microscopic active systems, and provides insight into the intricate role of hydrodynamic interaction on the onset of collective behavior of living and synthetic active matter.


[Phys. Rev. Fluids 4, 013701] Published Wed Jan 09, 2019

Frictional force on sliding drops

Physical Review Fluids - Wed, 01/09/2019 - 10:00

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

Atwood number effects on the instability of a uniform interface driven by a perturbed shock wave

Physical Review E - Tue, 01/08/2019 - 10:00

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

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