Latest papers in fluid mechanics
Author(s): Gerald J. Wang, Angelo Damone, Francesco Benfenati, Pietro Poesio, Gian Paolo Beretta, and Nicolas G. Hadjiconstantinou
At the nanoscale, and in particular in the presence of slip, hydrodynamic bending of interfaces between immiscible liquids becomes negligible. The dynamic contact angle is then governed by the Molecular Kinetic Theory (MKT) of Blake and collaborators.
[Phys. Rev. Fluids 4, 124203] Published Wed Dec 11, 2019
Author(s): Ehud Yariv
Asymptotic methods and conformal mappings are used to study mass or heat transport from a particle that is subject to a weak flow.
[Phys. Rev. Fluids 4, 124503] Published Wed Dec 11, 2019
Author(s): P. Salgado Sánchez, J. Fernández, I. Tinao, and J. Porter
Experiments on vibrated fluids confined in cylindrical and cuboidal containers were performed under the reduced gravity conditions of a parabolic flight. The results constitute a systematic quantitative investigation of the vibroequilibria effect, which refers to the reorientation of vibrated fluids...
[Phys. Rev. E 100, 063103] Published Tue Dec 10, 2019
Author(s): Franziska Henrich, Dorota Linke, Hans Martin Sauer, Edgar Dörsam, Steffen Hardt, Hans-Jürgen Butt, and Günter K. Auernhammer
The interaction of pinning and surfactant-induced changes of dynamic contact angles on receding contact lines is studied. With increasing surfactant concentration the surfactant-induced effects dominate over pinning effects. This behavior is correlated to the emptying of the surface structures.
[Phys. Rev. Fluids 4, 124202] Published Mon Dec 09, 2019
Role of large-scale advection and small-scale turbulence on vertical migration of gyrotactic swimmers
Author(s): C. Marchioli, H. Bhatia, G. Sardina, L. Brandt, and A. Soldati
The role of large-scale motions and small-scale turbulence on rising of small bottom-heavy swimmers is examined via high Reynolds number direct numerical simulation of turbulent free-surface flow. The swimmers’ rising efficiency is quantified via a new timescale that combines the stability number and the Kolmogorov timescale.
[Phys. Rev. Fluids 4, 124304] Published Mon Dec 09, 2019
Potential-core closing of temporally developing jets at Mach numbers between 0.3 and 2: Scaling and conditional averaging of flow and sound fields
Author(s): Christophe Bogey and Pierre Pineau
Using direct numerical simulation, the potential-core closing of temporally developing round jets at Mach numbers between 0.3 and 2 is shown to radiate strong axisymmetric acoustic waves in the downstream direction. The Mach number dependence and the generation mechanism of these waves are revealed.
[Phys. Rev. Fluids 4, 124601] Published Mon Dec 09, 2019
Author(s): Shancong Tao and Yi Zhou
A numerical study confirms that by using multiscale structures, turbulence with a wider range of scales can be generated. However, the multiscale-generated turbulence may not have a long-lasting memory and can eventually forget its multiscale initial conditions.
[Phys. Rev. Fluids 4, 124602] Published Mon Dec 09, 2019
Absolute instability of impinging leading edge vortices in a submodel of a bileaflet mechanical heart valve
Author(s): Hadi Zolfaghari and Dominik Obrist
Mechanical heart valves have been linked to the production of unphysiological turbulent blood flow. As a first step toward a model for laminar-turbulent transition in this flow, an absolute instability in the impinging leading-edge vortices that develop between the valve leaflets is identified.
[Phys. Rev. Fluids 4, 123901] Published Fri Dec 06, 2019
Author(s): Giovanni Lacagnina, Paruchuri Chaitanya, Tim Berk, Jung-Hoon Kim, Phillip Joseph, Bharathram Ganapathisubramani, Seyed Mohammad Hasheminejad, Tze Pei Chong, Oksana Stalnov, Kwing-So Choi, Muhammad Farrukh Shahab, Mohammad Omidyeganeh, and Alfredo Pinelli
A study of mechanisms of noise radiation from airfoils at high angles of attack (partial to full separation) identifies four different noise generation flow regimes. The relationship between noise, surface pressure, and shear layer turbulence is explored.
[Phys. Rev. Fluids 4, 123902] Published Fri Dec 06, 2019
Mitigation of turbophoresis in particle-laden turbulent channel flows by using incident electric fields
Author(s): M. Di Renzo, P. L. Johnson, M. Bassenne, L. Villafañe, and J. Urzay
The influence of electric forces on inertial particles in turbulent channel flows is explored using direct numerical simulations. It is found that the near-wall buildup of particle concentration due to turbophoresis can be reduced up to 2 orders of magnitude by imposing an ac electric field.
[Phys. Rev. Fluids 4, 124303] Published Fri Dec 06, 2019
Author(s): Antoine Renaud and Jacques Vanneste
The dispersion and reaction of a scalar patch by a random flow is investigated. A comparison of single realizations to the ensemble average shows explicitly that the two concentrations have very different tails, leading to different reaction front velocities in the fast-reacting problem.
[Phys. Rev. Fluids 4, 124502] Published Fri Dec 06, 2019
Author(s): Ming Yu, Chun-Xiao Xu, and Sergio Pirozzoli
Finite dilatational effects in wall-bounded compressible turbulence are investigated. We find that finite correlation between the solenoidal and the dilatational parts of the velocity field account for a nonnegligible fraction of the turbulent shear stress near walls.
[Phys. Rev. Fluids 4, 123402] Published Thu Dec 05, 2019
Author(s): Pei-Yi Zou, Yu-Hsiang Lai, and Jing-Tang Yang
In this work we studied the differences in flight kinematics and aerodynamics that could relate to differences in wing morphologies of a dragonfly and a damselfly. The damselflies and dragonflies normally fly with the fore wing or hind wing in the lead, respectively. The wing of the damselfly is pet...
[Phys. Rev. E 100, 063102] Published Wed Dec 04, 2019
Author(s): Evgenia Shabalina, Antoine Bérut, Mathilde Cavelier, Arnaud Saint-Jalmes, and Isabelle Cantat
A foam film is prepared in a controlled way, so that the top part of the film is much thicker than the bottom part. This situation is unstable under gravity and Rayleigh-Taylor-like fingers grow.The wavelength and the growth rate depend on the effective gravity and on the thick-film width.
[Phys. Rev. Fluids 4, 124001] Published Wed Dec 04, 2019
Author(s): Kunyun He, Francisco Campo-Cortés, Martyna Goral, Teresa López-León, and José Manuel Gordillo
The smallest compound droplets reported up to date, with outer diameters comparable with a red blood cell, are produced in a continuous way at frequencies exceeding 10 kHz from the capillary breakup of the coaxial cylindrical jets issued from the tip of the conical drops formed using an outer coflow.
[Phys. Rev. Fluids 4, 124201] Published Wed Dec 04, 2019
Systematic direct simulation Monte Carlo approach to characterize the effects of surface roughness on accommodation coefficients
Author(s): Kishore K. Kammara, Rakesh Kumar, Amit K. Singh, and Arun K. Chinnappan
The effects of surface roughness on accommodation coefficients are studied using the direct simulation Monte-Carlo (DSMC) approach. DSMC simulations are carried out by varying the roughness parameters. An empirical relationship between surface roughness and accommodation coefficients is established.
[Phys. Rev. Fluids 4, 123401] Published Tue Dec 03, 2019
Author(s): Pejman Sanaei and Linda J. Cummings
A simplified mathematical model, which characterizes membrane internal pore structure accounts for multiple simultaneous membrane fouling mechanisms (adsorption, blocking, and cake formation) and is able to predict the optimum permeability.
[Phys. Rev. Fluids 4, 124301] Published Tue Dec 03, 2019
Author(s): Shivakumar Athani and Pierre Rognon
We find evidence that the granular drag force on an object moving through a granular material is strongly enhanced when the object is accelerating. This effect can be explained by showing that the accelerating object accelerates the grains nearby, inducing an inertial resistance.
[Phys. Rev. Fluids 4, 124302] Published Tue Dec 03, 2019
Generation of a large-scale vorticity in a fast-rotating density-stratified turbulence or turbulent convection
Author(s): Igor Rogachevskii and Nathan Kleeorin
We find an instability resulting in generation of large-scale vorticity in a fast-rotating small-scale turbulence or turbulent convection with inhomogeneous fluid density along the rotational axis in anelastic approximation. The large-scale instability causes excitation of two modes: (i) the mode wi...
[Phys. Rev. E 100, 063101] Published Mon Dec 02, 2019
Author(s): Wassim Dhaouadi and John M. Kolinski
Direct observation of the liquid film binding buoyant Bretherton bubbles reveals a van-der-Waals-stabilized thickness.
[Phys. Rev. Fluids 4, 123601] Published Mon Dec 02, 2019