Physical Review Fluids

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Heating-induced drag reduction in relative movement of parallel plates

Tue, 09/04/2018 - 11:00

Author(s): J. M. Floryan, S. Shadman, and M. Z. Hossain

A new analysis shows that the force required to maintain the relative movement of parallel plates is significantly reduced when these plates are heated in a spatially nonuniform manner.

[Phys. Rev. Fluids 3, 094101] Published Tue Sep 04, 2018

Inviscid simulations of expansion waves propagating into structured particle beds at low volume fractions

Tue, 09/04/2018 - 11:00

Author(s): Goran Marjanovic, Jason Hackl, Mrugesh Shringarpure, Subramanian Annamalai, Thomas L. Jackson, and S. Balachandar

We perform fully resolved simulations of expansion waves propagating into particle beds of varying volume fractions using the discontinuous Galerkin spectral element method. We validate state-of-the-art drag models and predict the final state of the particle bed using isentropic flow relations.

[Phys. Rev. Fluids 3, 094301] Published Tue Sep 04, 2018

Finite-size Lagrangian coherent structures in thermocapillary liquid bridges

Tue, 09/04/2018 - 11:00

Author(s): Francesco Romanò and Hendrik C. Kuhlmann

A numerical investigation shows that finite-size Lagrangian coherent structures result from bulk transport near Kolmogorov-Arnold-Moser tori and a dissipative effect that finite-size particles experience near the free surface.

[Phys. Rev. Fluids 3, 094302] Published Tue Sep 04, 2018

Intermittency enhancement in quantum turbulence in superfluid $^{4}\mathrm{He}$

Tue, 09/04/2018 - 11:00

Author(s): Emil Varga, Jian Gao, Wei Guo, and Ladislav Skrbek

Intermittency of quasiclassical quantum turbulence in superfluid 4He is experimentally found to be temperature dependent and enhanced for a range of temperatures compared to classical turbulence, in contrast with nearly flow-independent intermittency of turbulence in classical fluids.

[Phys. Rev. Fluids 3, 094601] Published Tue Sep 04, 2018

Theoretical framework to analyze the combined effect of surface tension and viscosity on the damping rate of sloshing waves

Tue, 09/04/2018 - 11:00

Author(s): Francesco Viola and François Gallaire

A dynamic meniscus affects viscous dissipation of oscillating contact lines. A theoretical proposal, marrying viscous sloshing dynamics and a realistic contact line model including contact angle hysteresis, finds that both the wave damping rate and frequency increase at small amplitude.

[Phys. Rev. Fluids 3, 094801] Published Tue Sep 04, 2018

Spectrum of shallow water gravity waves generated by confined two-dimensional turbulence

Tue, 09/04/2018 - 11:00

Author(s): Claudio Falcón and Edgar Knobloch

Two-dimensional turbulence can generate shallow water waves. These waves carry information about the structure of their turbulent source. A theoretical calculation of the wave spectrum is proposed, which may lead to an insightful way to characterize turbulence.

[Phys. Rev. Fluids 3, 094802] Published Tue Sep 04, 2018

Energy contributions by inner and outer motions in turbulent channel flows

Fri, 08/31/2018 - 11:00

Author(s): Ruifeng Hu and Xiaojing Zheng

In a new study, the critical Reynolds number for the emergence of outer motions in turbulent channel flows is determined to be Reτ≈110. The growing significance of outer motions is obtained by subtracting the inner contributions from the total at low to moderate Reynolds numbers.

[Phys. Rev. Fluids 3, 084607] Published Fri Aug 31, 2018

Rayleigh-Taylor instability under a spherical substrate

Thu, 08/30/2018 - 11:00

Author(s): Gioele Balestra, David Minh-Phuc Nguyen, and François Gallaire

The Rayleigh-Taylor instability of a thin viscous film coating the inside of a spherical substrate is studied. The instability properties are investigated by performing a linear optimal transient growth analysis. The pattern formation is further analyzed using nonlinear numerical simulations.

[Phys. Rev. Fluids 3, 084005] Published Thu Aug 30, 2018

Geometric state function for two-fluid flow in porous media

Thu, 08/30/2018 - 11:00

Author(s): James E. McClure, Ryan T. Armstrong, Mark A. Berrill, Steffen Schlüter, Steffen Berg, William G. Gray, and Cass T. Miller

It is shown that the geometric state of fluids within porous media can be expressed in terms of a relationship that links the fluid volume, surface area, mean curvature, and Euler characteristic. The relationship is able to accurately model complex changes in fluid connectivity and structure.

[Phys. Rev. Fluids 3, 084306] Published Thu Aug 30, 2018

Direct numerical simulations of multifluid flows in a vertical channel undergoing topology changes

Thu, 08/30/2018 - 11:00

Author(s): Jiacai Lu and Gretar Tryggvason

Multifluid flows with changes in the topology of the interface separating the different fluids, in a turbulent vertical channel, are examined using direct numerical simulations. The results show how different surface tension changes the evolution of the flow and the interface topology.

[Phys. Rev. Fluids 3, 084401] Published Thu Aug 30, 2018

Dynamics of viscoelastic filaments based on Onsager principle

Wed, 08/29/2018 - 11:00

Author(s): Jiajia Zhou and Masao Doi

Exponential thinning of a viscoelastic filament is analyzed using the Onsager variational principle.

[Phys. Rev. Fluids 3, 084004] Published Wed Aug 29, 2018

Wavelet multiresolution analysis of particle-laden turbulence

Wed, 08/29/2018 - 11:00

Author(s): Maxime Bassenne, Parviz Moin, and Javier Urzay

The preferential concentration of inertial particles in isotropic turbulence is studied using wavelets, enabling the joint scale-space analysis of the flow field of the carrier phase, the concentration field of the dispersed phase, and interphase conditioned statistics.

[Phys. Rev. Fluids 3, 084304] Published Wed Aug 29, 2018

Heat transfer from an array of resolved particles in turbulent flow

Wed, 08/29/2018 - 11:00

Author(s): Yayun Wang and Andrea Prosperetti

Resolved simulations of turbulent flow past a fixed planar array of cold particles show the fundamental differences between velocity and temperature fields, cast light on the limitations of the point particle model and illustrate the mechanism by which turbulence disrupts the thermal wakes.

[Phys. Rev. Fluids 3, 084305] Published Wed Aug 29, 2018

Derivation of a realistic forcing term to reproduce the turbulent characteristics of round jets on the centerline

Wed, 08/29/2018 - 11:00

Author(s): Kyupaeck Jeff Rah, Chandru Dhandapani, and Guillaume Blanquart

Turbulence forcing techniques are often required in the numerical simulation of turbulent flows. A novel forcing technique, based on physics, is devised to reproduce the centerline turbulent characteristics of round jets in a triply periodic box.

[Phys. Rev. Fluids 3, 084606] Published Wed Aug 29, 2018

Vortex ring impingement on a wall with a coaxial aperture

Wed, 08/29/2018 - 11:00

Author(s): JiaCheng Hu and Sean D. Peterson

An investigation of the interaction of a vortex ring colliding with a coaxially aligned aperture, which extends the classical problem of a vortex ring impacting a solid wall, examines the behaviors of near-wall vortices in the proximity of a structural discontinuity (aperture tip).

[Phys. Rev. Fluids 3, 084701] Published Wed Aug 29, 2018

Droplet fragmentation using a mesh

Tue, 08/28/2018 - 11:00

Author(s): Dan Soto, Henri-Louis Girard, Antoine Le Helloco, Thomas Binder, David Quéré, and Kripa K. Varanasi

Factors governing atomization of droplets impacting a mesh, starting with the elementary unit of a single hole, are investigated. It is shown how this process can be used to generate finely controlled sprays with micrometric droplet sizes and low kinetic energy, as is critical for agricultural applications.

[Phys. Rev. Fluids 3, 083602] Published Tue Aug 28, 2018

Wetting over pre-existing liquid films

Tue, 08/28/2018 - 11:00

Author(s): Hannu Teisala, Clarissa Schönecker, Anke Kaltbeitzel, Werner Steffen, Hans-Jürgen Butt, and Doris Vollmer

Wetting over liquid films governs important phenomena but is poorly understood. A water front moving over a micrometer-thick film of silicone oil on a solid surface is imaged. Capillary suction in the meniscus induces thinning of the oil film and a wavelike film profile with local backflows.

[Phys. Rev. Fluids 3, 084002] Published Tue Aug 28, 2018

Fragmentation of magnetic particle aggregates in turbulence

Fri, 08/24/2018 - 11:00

Author(s): H. M. De La Rosa Zambrano, G. Verhille, and P. Le Gal

Aggregation and fragmentation are frequently observed in industrial and natural systems. In an experimental study, an initially large aggregate of magnetic particles is broken by the turbulent fluctuations of a flow. The size of the resulting clusters is measured using three-dimensional reconstruction.

[Phys. Rev. Fluids 3, 084605] Published Fri Aug 24, 2018

Slippage effect on the dispersion coefficient of a passive solute in a pulsatile electro-osmotic flow in a microcapillary

Thu, 08/23/2018 - 11:00

Author(s): J. Muñoz, J. Arcos, O. Bautista, and F. Méndez

The dispersion coefficient of a passive solute into a pulsatile electroosmotic flow with slippage at the microcapillary wall is derived. We found that the slip condition can enhance the dispersion coefficient by up to two orders of magnitude over the no-slip condition.

[Phys. Rev. Fluids 3, 084503] Published Thu Aug 23, 2018

Publisher's Note: Hot particles attract in a cold bath [Phys. Rev. Fluids 2, 043103 (2017)]

Thu, 08/23/2018 - 11:00

Author(s): Hidenori Tanaka, Alpha A. Lee, and Michael P. Brenner

[Phys. Rev. Fluids 3, 089901] Published Thu Aug 23, 2018