Physical Review Fluids

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Updated: 14 hours 53 min ago

Liquid spreading on cold surfaces: Solidification-induced stick-slip dynamics

Wed, 03/27/2019 - 10:00

Author(s): Rémy Herbaut, Philippe Brunet, Laurent Limat, and Laurent Royon

Spreading of liquid on a cold substrate with freezing is investigated. Experimental investigation of the criterion for a solidification-induced pinning of the liquid near the triple line finds that below a temperature-dependent velocity, spreading shows stick-slip dynamics.

[Phys. Rev. Fluids 4, 033603] Published Wed Mar 27, 2019

Using vortex identifiers to build eddy-viscosity subgrid-scale models for large-eddy simulation

Tue, 03/26/2019 - 10:00

Author(s): Xingjun Fang, Bing-Chen Wang, and Donald J. Bergstrom

A generalized framework of incorporating vortex identifiers into subgrid-scale models for large-eddy simulation is presented. The proposed models can automatically identify the under-resolved vortex stretching process and drain energy from the inertial subrange.

[Phys. Rev. Fluids 4, 034606] Published Tue Mar 26, 2019

Scattering of surface shallow water waves on a draining bathtub vortex

Tue, 03/26/2019 - 10:00

Author(s): Semyon Churilov and Yury Stepanyants

Wave scattering on a bathtub vortex in shallow water is studied in the linear approximation. The results obtained are relevant to the interpretation of laboratory experiments and can be considered the hydrodynamic model of wave scattering by a rotating black hole in general relativity.

[Phys. Rev. Fluids 4, 034704] Published Tue Mar 26, 2019

Elastohydrodynamics of swimming helices: Effects of flexibility and confinement

Mon, 03/25/2019 - 10:00

Author(s): John LaGrone, Ricardo Cortez, and Lisa Fauci

We examine the swimming of an elastic helix rotated by a torque at its base, both in free-space and confined to a tube. The image depicts the envelope of an excursion of a filament centerline over one rotation; the blue is the surface of the finite-radius helical filament at one snapshot in time.

[Phys. Rev. Fluids 4, 033102] Published Mon Mar 25, 2019

Experimental study of convection in the compressible regime

Mon, 03/25/2019 - 10:00

Author(s): Rémi Menaut, Yoann Corre, Ludovic Huguet, Thomas Le Reun, Thierry Alboussière, Michael Bergman, Renaud Deguen, Stéphane Labrosse, and Marc Moulin

Compressible thermal convection is experimentally studied. In the large apparent gravity of a rotor centrifuge, using xenon gas, an adiabatic temperature difference of 14 °C over a height equal to 4 cm is obtained. Large Coriolis forces impose a quasigeostrophic regime.

[Phys. Rev. Fluids 4, 033502] Published Mon Mar 25, 2019

Diffusion-driven transition between two regimes of viscous fingering

Mon, 03/25/2019 - 10:00

Author(s): Thomas E. Videbæk and Sidney R. Nagel

Diffusion between miscible fluids in the viscous-fingering instability produces an unexpected transition into a novel pattern. Usually thought of as a two-dimensional phenomena, this works shows the importance of three-dimensional structure to the patterns that form.

[Phys. Rev. Fluids 4, 033902] Published Mon Mar 25, 2019

Inviscid flow separation at the crest of an erodible dune

Mon, 03/25/2019 - 10:00

Author(s): F. Charru and P. Luchini

Potential flow analysis is used to find the elevation profile of traveling dunes of given volume and locate the brink point where the flow separates without singularity.

[Phys. Rev. Fluids 4, 034304] Published Mon Mar 25, 2019

Streamline segment statistics propagation in inhomogeneous turbulence

Mon, 03/25/2019 - 10:00

Author(s): A. Rubbert, M. Albers, and W. Schröder

Streamline segment statistics are collected from tomographic particle image velocimetry and direct numerical simulation data of a turbulent wavy channel flow. The model equation for such statistics is adapted for inhomogeneous turbulence. The novel formulation is applied to explain the observations and identify the locally acting mechanisms.

[Phys. Rev. Fluids 4, 034605] Published Mon Mar 25, 2019

Flow structures govern particle collisions in turbulence

Thu, 03/21/2019 - 10:00

Author(s): Jason R. Picardo, Lokahith Agasthya, Rama Govindarajan, and Samriddhi Sankar Ray

Direct numerical simulations find that rapid head-on collisions of particles mostly occur in regions of straining compared to vortical regions, and that intense vortex tubes conspire with enveloping straining sheets, in the form of vortex-strain worm-rolls, to generate violent collisions.

[Phys. Rev. Fluids 4, 032601(R)] Published Thu Mar 21, 2019

Scattering of liquid droplets from axisymmetric targets

Thu, 03/21/2019 - 10:00

Author(s): Jacob Hale and Jacob Boudreau

A meniscus formed around a vertical cylinder looks and behaves like a repulsive central potential, deflecting noncoalescent droplets analogous to Rutherford scattering. The scattering behavior is used to probe the potential of the cylindrical meniscus, confirming theoretical models for its shape.

[Phys. Rev. Fluids 4, 033602] Published Thu Mar 21, 2019

Modal analysis with proper orthogonal decomposition of hypersonic separated flows over a double wedge

Tue, 03/19/2019 - 10:00

Author(s): Ozgur Tumuklu, Deborah A. Levin, and Vassilis Theofilis

A study combining direct simulation Monte Carlo simulations with window proper orthogonal decomposition investigates the temporal characteristics of unsteady, laminar shock boundary-layer interactions for different gas mixtures for an Edney type-IV flow.

[Phys. Rev. Fluids 4, 033403] Published Tue Mar 19, 2019

Imbibition and evaporation of droplets of colloidal suspensions on permeable substrates

Tue, 03/19/2019 - 10:00

Author(s): Truong Pham and Satish Kumar

Colloidal particles inside an evaporated droplet on a solid substrate are often preferentially deposited at the droplet contact line, a phenomenon known as the coffee-ring effect. A study shows how this phenomenon is affected by the permeability of the substrate.

[Phys. Rev. Fluids 4, 034004] Published Tue Mar 19, 2019

Drag reduction mechanisms of a car model at moderate yaw by bi-frequency forcing

Tue, 03/19/2019 - 10:00

Author(s): Ruiying Li, Jacques Borée, Bernd R. Noack, Laurent Cordier, and Fabien Harambat

We propose a windward bi-frequency control strategy to manipulate experimentally the wake past a yawed car model using pulsed jets. By varying the low frequency value in the actuation, we can provide a complete authority for the manipulation of the mean wake orientation and reduce drag.

[Phys. Rev. Fluids 4, 034604] Published Tue Mar 19, 2019

Elasto-capillary adhesion: Effect of deformability on adhesion strength and detachment

Mon, 03/18/2019 - 10:00

Author(s): Matthew Butler, Finn Box, Thomas Robert, and Dominic Vella

Inspired by the droplet-mediated adhesion of insects, the adhesion between soft and rigid surfaces mediated by a droplet is studied. Deformability allows for enhanced adhesion as well as new routes for “unsticking,” but the dynamics of adhesion also plays a role.

[Phys. Rev. Fluids 4, 033601] Published Mon Mar 18, 2019

Anomalous collapse of interacting bubbles in a fluidized bed: A magnetic resonance imaging study

Mon, 03/18/2019 - 10:00

Author(s): C. M. Boyce, A. Penn, A. Padash, M. Lehnert, K. P. Pruessmann, and C. R. Müller

Rapid magnetic resonance imaging shows how bubbles collapse in fluidized beds as a result of gas channeling to neighboring bubbles.

[Phys. Rev. Fluids 4, 034303] Published Mon Mar 18, 2019

Importance of small-scale anisotropy in the turbulent/nonturbulent interface region of turbulent free shear flows

Mon, 03/18/2019 - 10:00

Author(s): O. R. H. Buxton, M. Breda, and K. Dhall

Turbulent flows are often bounded by nonturbulent fluid with a sharp interface between the two flow states. Drawing a parallel between this interface and the wall in a wall-bounded flow and similarly, to wall-bounded turbulence, shows the importance of the anisotropy very close to the interface.

[Phys. Rev. Fluids 4, 034603] Published Mon Mar 18, 2019

Predictive large-eddy-simulation wall modeling via physics-informed neural networks

Fri, 03/15/2019 - 10:00

Author(s): X. I. A. Yang, S. Zafar, J.-X. Wang, and H. Xiao

A study shows that when trained using channel flow data at just one Reynolds number and informed with known flow physics, the neural network works robustly as a wall model in large-eddy simulation (LES) of channel flow at any Reynolds number. It also outperforms the equilibrium wall model in LES of a 3D boundary layer flow.

[Phys. Rev. Fluids 4, 034602] Published Fri Mar 15, 2019

Orientation dependent elastic stress concentration at tips of slender objects translating in viscoelastic fluids

Thu, 03/14/2019 - 10:00

Author(s): Chuanbin Li, Becca Thomases, and Robert D. Guy

The elastic stress generated moving in a purely viscous flow around a slender cylinder is found to be large near the tips, and larger when the flow is parallel to the axis.

[Phys. Rev. Fluids 4, 031301(R)] Published Thu Mar 14, 2019

Effect of heat-flux boundary conditions on the Rayleigh-Bénard instability in a rarefied gas

Thu, 03/14/2019 - 10:00

Author(s): Y. Ben-Ami and A. Manela

The effect of heat-flux conditions on the Rayleigh-Bénard convection in a rarefied gas is investigated, extending instability to higher rarefaction rates compared with the isothermal walls case. The deviation from the Boussinesq limit with increasing compressibility is analyzed.

[Phys. Rev. Fluids 4, 033402] Published Thu Mar 14, 2019

Turning depths: Evanescent to propagating wave kinetic energy density

Thu, 03/14/2019 - 10:00

Author(s): Allison Lee and Julie Crockett

Evanescent regions exist in numerous areas of the deep ocean where the stratification also varies with depth. Using theoretical predictions and experiments, the kinetic energy density in propagating internal waves generated from these evanescent regions is explored.

[Phys. Rev. Fluids 4, 034803] Published Thu Mar 14, 2019