Physical Review Fluids

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Recent articles in Physical Review Fluids
Updated: 18 hours 14 min ago

Turbulence dissipation and the role of coherent structures in the near wake of a square prism

Wed, 12/26/2018 - 10:00

Author(s): F. Alves Portela, G. Papadakis, and J. C. Vassilicos

An analysis shows that on the centerline of a planar wake, turbulent dissipation obeys the nonequilibrium scaling, provided that the large-scale contribution of the coherent motions is disregarded. In that same region, the dissipations associated with coherent and incoherent motions vary together.

[Phys. Rev. Fluids 3, 124609] Published Wed Dec 26, 2018

Self-sustaining process in Taylor-Couette flow

Fri, 12/21/2018 - 10:00

Author(s): Tommy Dessup, Laurette S. Tuckerman, José Eduardo Wesfreid, Dwight Barkley, and Ashley P. Willis

The Self-Sustaining Process (SSP) proposed in the 1990s by Waleffe is a widely-accepted building block of transition to turbulence in shear flows such as plane Couette flow. Although inspired by the rolls and waves of Taylor-Couette flow, the SSP had not been investigated for this flow until now.

[Phys. Rev. Fluids 3, 123902] Published Fri Dec 21, 2018

Drying and percolation in correlated porous media

Fri, 12/21/2018 - 10:00

Author(s): Soumyajyoti Biswas, Paolo Fantinel, Oshri Borgman, Ran Holtzman, and Lucas Goehring

We show that local structure, in an otherwise random medium, can change the nature of invasion percolation phenomena, including multiphase fluid flows. By combining microfluidic drying experiments with simple models we explain how local correlations in pore sizes lead to more extreme dynamics.

[Phys. Rev. Fluids 3, 124307] Published Fri Dec 21, 2018

Large-scale intermittency and rare events boosted at dimensional crossover in anisotropic turbulence

Fri, 12/21/2018 - 10:00

Author(s): Keiko Takahashi, Koji Goto, Ryo Onishi, and Masatoshi Imada

Our numerical simulation finds that flattened three dimensional turbulence generates strong intermittency at the crossover scale between two and three dimensions. This provides a mechanism for disaster causing extreme events below the synoptic scale in the atmosphere such as tropical cyclones.

[Phys. Rev. Fluids 3, 124607] Published Fri Dec 21, 2018

Effects of disturbance on detonation initiation in ${\mathrm{H}}_{2}/{\mathrm{O}}_{2}/{\mathrm{N}}_{2}$ mixture

Thu, 12/20/2018 - 10:00

Author(s): Yuan Wang, Wang Han, Ralf Deiterding, and Zheng Chen

Two-dimensional simulations are conducted to assess the effects of disturbance on detonation initiation. A disturbance can induce a complex shock wave interaction which induces a local explosion. Disturbances can thus be used to promote detonation initiation.

[Phys. Rev. Fluids 3, 123201] Published Thu Dec 20, 2018

Multifractality of fine bubbles in turbulence due to lift

Thu, 12/20/2018 - 10:00

Author(s): Itzhak Fouxon, Gihun Shim, Seulgi Lee, and Changhoon Lee

An equation of motion is derived for isolated bubbles in turbulence, an equation similar to that governing phytoplankton. Simulations show the clustering of bubbles in vertical columns.

[Phys. Rev. Fluids 3, 124305] Published Thu Dec 20, 2018

Morphodynamics of a sediment bed in a fluid-filled cylinder during spin-down: An experimental study

Thu, 12/20/2018 - 10:00

Author(s): A. S. González-Vera, M. Duran-Matute, and G. J. F. van Heijst

Laboratory experiments on the evolution of a sediment bed under a spin-down flow show the emergence of diverse types of patterns. The net radially inward sediment transport is quantified and explained through an analytical derivation of the total radial force exerted on the bed.

[Phys. Rev. Fluids 3, 124306] Published Thu Dec 20, 2018

Magnetic structure, dipole reversals, and $1/f$ noise in resistive MHD spherical dynamos

Wed, 12/19/2018 - 10:00

Author(s): M. Fontana, P. D. Mininni, and P. Dmitruk

A parametric study of dynamos in a rotating sphere shows a rich space of dynamic solutions, with stationary, aperiodic, and small-scale dynamo regimes controlled by Ekman and Reynolds numbers. Magnetic reversals are observed, displaying 1/f noise and statistics reminiscent of geodynamo observations.

[Phys. Rev. Fluids 3, 123702] Published Wed Dec 19, 2018

Film coating on a small sphere crossing an oil-water interface

Wed, 12/19/2018 - 10:00

Author(s): Haosheng Chen (陈皓生), Qinda Xu (徐勤达), Shuaishuai Liang (梁帅帅), and Jiang Li (李疆)

Experiments show that small spheres can pass through an oil-water interface and be coated with a predictable oil film when the Bond number is between 1.5 and 7.5. The film thickness is approximately proportional to the Bond number, which makes it a convenient method to coat particles with a designed film thickness.

[Phys. Rev. Fluids 3, 124003] Published Wed Dec 19, 2018

Influence of particle dynamics on the instability for pattern formation in shallow pulsed beds

Wed, 12/19/2018 - 10:00

Author(s): Lilian de Martín

Standing wave patterns can occur both in vibrated granular layers and pulsed fluidized beds. Although the different type of excitation results in a different definition of the driving parameters and instability curve, a theoretical study shows that the instability criterion in both systems is similar.

[Phys. Rev. Fluids 3, 124304] Published Wed Dec 19, 2018

Drag on pairs of square section obstacles in free-surface flows

Tue, 12/18/2018 - 10:00

Author(s): Francis H. Robertson and Gregory F. Lane-Serff

The effect of one obstacle on the drag on a second obstacle is measured for square obstacles in subcritical open channel flow. The lowest drag occurs when one obstacle is shielded directly behind another, and the largest drag occurs on a slightly upstream obstacle in near side-by-side arrangements.

[Phys. Rev. Fluids 3, 123802] Published Tue Dec 18, 2018

Post-pinch-off relaxation of two-dimensional droplets in a Hele-Shaw cell

Tue, 12/18/2018 - 10:00

Author(s): Dhirendra Tiwari, Lionel Mercury, Marcel Dijkstra, Himanshu Chaudhary, and José Federico Hernández-Sánchez

The relaxation of a liquid drop in a Hele-Shaw cell is observed experimentally and then modeled successfully.

[Phys. Rev. Fluids 3, 124202] Published Tue Dec 18, 2018

Unsteady motion of a long bubble or droplet in a self-rewetting system

Mon, 12/17/2018 - 10:00

Author(s): B. R. Duffy, S. K. Wilson, J. J. A. Conn, and K. Sefiane

The evolution of the shape (but not the position) of a long bubble or droplet in a self-rewetting system in a nonuniformly heated tube is shown to be driven entirely by Marangoni effects: a wide droplet widens (and ultimately fills the cross section of the tube), whereas a narrow droplet narrows.

[Phys. Rev. Fluids 3, 123603] Published Mon Dec 17, 2018

Hierarchical random additive model for the spanwise and wall-normal velocities in wall-bounded flows at high Reynolds numbers

Mon, 12/17/2018 - 10:00

Author(s): X. I. A. Yang, R. Baidya, Yu Lv, and I. Marusic

Both the spanwise and the vertical velocity components in high-Reynolds-number wall-bounded flows may be modeled via a random additive process. Evidence shows that a hierarchical, treelike structure exists for the spanwise velocity component.

[Phys. Rev. Fluids 3, 124606] Published Mon Dec 17, 2018

Cascade leading to the emergence of small structures in vortex ring collisions

Mon, 12/17/2018 - 10:00

Author(s): Ryan McKeown, Rodolfo Ostilla-Mónico, Alain Pumir, Michael P. Brenner, and Shmuel M. Rubinstein

A novel breakdown mechanism is observed during the head-on collision of two vortex rings. The interacting cores locally flatten into extremely thin vortex sheets and split into smaller daughter filaments iteratively over two generations, leading to the rapid emergence of fine-scale vortices.

[Phys. Rev. Fluids 3, 124702] Published Mon Dec 17, 2018

Viscous damping of gravity-capillary waves: Dispersion relations and nonlinear corrections

Mon, 12/17/2018 - 10:00

Author(s): Andrea Armaroli, Debbie Eeltink, Maura Brunetti, and Jérôme Kasparian

An envelope equation to model the propagation of surface waves in deep viscous fluids is proposed. The dispersion relation comprising viscosity and surface tension is expressed as an operator and used to generalize the universal nonlinear Schrödinger equation and quantify nonlinear damping.

[Phys. Rev. Fluids 3, 124803] Published Mon Dec 17, 2018

Apparent slip and drag reduction for the flow over superhydrophobic and lubricant-impregnated surfaces

Thu, 12/13/2018 - 10:00

Author(s): Edoardo Alinovi and Alessandro Bottaro

The flow within microscopic indentations filled with a lubricant fluid is studied by varying viscosity ratio, surface tension, and lubricant-to-working-fluid volume fraction. This yields protrusion heights that readily quantify the drag reduction of a lubricant-impregnated microstructured surface.

[Phys. Rev. Fluids 3, 124002] Published Thu Dec 13, 2018

Data-assimilated low-order vortex modeling of separated flows

Thu, 12/13/2018 - 10:00

Author(s): Darwin Darakananda, André Fernando de Castro da Silva, Tim Colonius, and Jeff D. Eldredge

This works shows for the first time that an inexpensive ensemble of low-order vortex models can accurately capture the aerodynamics of a low Reynolds number separated flow, even when disturbed by gusts, when it assimilates measured surface pressures.

[Phys. Rev. Fluids 3, 124701] Published Thu Dec 13, 2018

An amplitude equation for surface gravity wave-topography interactions

Thu, 12/13/2018 - 10:00

Author(s): Jim Thomas and Ray Yamada

A new amplitude equation that captures the effect of arbitrary topography on surface waves is presented. It can be integrated more quickly than the fully nonlinear equations, while accurately capturing the wave dynamics.

[Phys. Rev. Fluids 3, 124802] Published Thu Dec 13, 2018

Childhood of turbulent spots in a shear flow

Wed, 12/12/2018 - 10:00

Author(s): M. Couliou and R. Monchaux

We numerically investigate temporal aspects of turbulent spot spreading in plane Couette flow for transitional Reynolds numbers, focusing on streamwise spreading. From the topology of turbulent spots and associated large-scale flows, we propose a decomposition of the streamwise growth rate.

[Phys. Rev. Fluids 3, 123901] Published Wed Dec 12, 2018