# Latest papers in fluid mechanics

### Renormalization of viscosity in wavelet-based model of turbulence

Author(s): M. V. Altaisky, M. Hnatich, and N. E. Kaputkina

Statistical theory of turbulence in viscid incompressible fluid, described by the Navier-Stokes equation driven by random force, is reformulated in terms of scale-dependent fields ua(x), defined as wavelet-coefficients of the velocity field u taken at point x with the resolution a. Applying quantum ...

[Phys. Rev. E 98, 033116] Published Mon Sep 24, 2018

### Direct numerical simulation of particle sedimentation in a Bingham fluid

Author(s): A. R. Koblitz, S. Lovett, and N. Nikiforakis

Two-dimensional numerical simulations of a suspension of sedimenting particles in a Bingham fluid find three possible regimes: all, a fraction, and none of the particles sedimenting.

[Phys. Rev. Fluids 3, 093302] Published Mon Sep 24, 2018

### Viscous fingering of a draining suspension

Author(s): Yun Chen, Frank Malambri, and Sungyon Lee

Viscous fingering arises as air invades a draining viscous suspension. Experiments show that suspended particles delay the onset of fingering but also accelerate its growth rate. In addition, particles of select sizes are observed to coat the channel surfaces and not drain.

[Phys. Rev. Fluids 3, 094001] Published Mon Sep 24, 2018

### Confinement effects on gravity-capillary wave turbulence

Author(s): Roumaissa Hassaini and Nicolas Mordant

The effect of confinement in a high-aspect-ratio channel on the statistical properties of weak turbulence of gravity-capillary waves at the surface of water is investigated. Discreteness due to confinement coexists with an almost one-dimensional kinetic sort of wave turbulence.

[Phys. Rev. Fluids 3, 094805] Published Mon Sep 24, 2018

### Rolling and slipping of droplets on superhydrophobic surfaces

Author(s): A. F. W. Smith, K. Mahelona, and S. C. Hendy

The leaves of many plants are superhydrophobic, a property that may have evolved to clean the leaves by encouraging water droplets to bead up and roll off. Superhydrophobic surfaces can also exhibit reduced friction, and liquids flowing over such surfaces have been found to slip in apparent violatio...

[Phys. Rev. E 98, 033113] Published Fri Sep 21, 2018

### Membrane filtration with complex branching pore morphology

Author(s): Pejman Sanaei and Linda J. Cummings

An idealized first-principles model describing filtration of a feed solution containing small particles in a microstructured porous membrane is presented. Optimal configurations for the pore microstructure are identified in terms of maximizing throughput of filtered fluid and filter lifetime.

[Phys. Rev. Fluids 3, 094305] Published Fri Sep 21, 2018

### Inertioelastic Poiseuille flow over a wavy surface

Author(s): Simon J. Haward, Jacob Page, Tamer A. Zaki, and Amy Q. Shen

Experimental evidence is presented for the existence of critical layers in inertioelastic shear flows over wavy surfaces, where theory predicts amplification of the spanwise vorticity.

[Phys. Rev. Fluids 3, 091302(R)] Published Fri Sep 21, 2018

### Scaling laws of top jet drop size and speed from bubble bursting including gravity and inviscid limit

Author(s): Alfonso M. Gañán-Calvo

Scaling laws are proposed for the size and the velocity of the droplet which is ejected when a bubble rises to a free surface and bursts. These new scalings consistently incorporate the effect of gravity and the limit of negligible viscosity of the liquid.

[Phys. Rev. Fluids 3, 091601(R)] Published Thu Sep 20, 2018

### Onset of three-dimensionality in supersonic flow over a slender double wedge

Author(s): Sidharth GS, Anubhav Dwivedi, Graham V. Candler, and Joseph W. Nichols

An investigation shows that laminar supersonic flow on a 2D compression corner can destabilize to become 3D beyond a critical turn angle. This compressible instability resides in the recirculating flow, producing spiral wall flow patterns postseparation and wall temperature streaks downstream.

[Phys. Rev. Fluids 3, 093901] Published Wed Sep 19, 2018

### Large-eddy simulation of turbulent flow over spanwise-offset barchan dunes: Interdune vortex stretching drives asymmetric erosion

Author(s): Chao Wang and William Anderson

The coupling between turbulent flow physics and barchan dune geometry is important to dune migration, morphology of individual dunes, and the morphodynamics of merging and separating proximal dunes. Large-eddy simulation was used to model turbulent, inertial-dominated flow over a series of static ba...

[Phys. Rev. E 98, 033112] Published Tue Sep 18, 2018

### Turbulent/nonturbulent interfaces in high-resolution direct numerical simulation of temporally evolving compressible turbulent boundary layers

Author(s): Xinxian Zhang, Tomoaki Watanabe, and Koji Nagata

Turbulent-nonturbulent interfaces are studied in temporally evolving subsonic and supersonic turbulent boundary layers by comparing the results of direct numerical simulations with the entrainment model based on a single vortex and the theory for spatially evolving boundary layers.

[Phys. Rev. Fluids 3, 094605] Published Tue Sep 18, 2018

### Wake behind a concave curved cylinder

Author(s): Fengjian Jiang, Bjørnar Pettersen, Helge I. Andersson, Jongmin Kim, and Sungtae Kim

The wake behind a concave, curved cylinder configuration is investigated at different Reynolds numbers. Distinctly different wake flow regimes were observed in the computed flow field, including oblique vortex shedding and dislocations. The crucial influence of a straight vertical extension is explored.

[Phys. Rev. Fluids 3, 094804] Published Tue Sep 18, 2018

### Enstrophy spectrum in freely decaying two-dimensional self-similar turbulent flow

Author(s): Igor Vigdorovich

We consider freely decaying two-dimensional homogeneous and isotropic turbulent motion in a self-similar limit that is achieved at large Reynolds numbers based on time and the mean kinetic energy of the flow provided that initial average enstrophy tends to infinity as fluid viscosity tens to zero. I...

[Phys. Rev. E 98, 033110] Published Mon Sep 17, 2018

### Large-eddy simulation and Reynolds-averaged Navier-Stokes modeling of a reacting Rayleigh-Taylor mixing layer in a spherical geometry

Author(s): Brandon E. Morgan, Britton J. Olson, Wolfgang J. Black, and Jacob A. McFarland

Tenth-order compact difference code *Miranda* is used to perform large-eddy simulation (LES) of a hydrogen gas–plastic mixing layer in a spherical geometry. Once the mixing layer has achieved self-similar growth, it is heated to 1 keV, and the second-order arbitrary Lagrangian-Eulerian (ALE) code *Ares*...

[Phys. Rev. E 98, 033111] Published Mon Sep 17, 2018

### Inertia-driven jetting regimes in microfluidic coflows

Author(s): Fan Zhang, Arnaud Erriguible, Théo Gavoille, Michaël T. Timko, and Samuel Marre

Inertial breakup modes are identified at microscale for co-flowing jets using a high-pressure mixer.

[Phys. Rev. Fluids 3, 092201(R)] Published Mon Sep 17, 2018

### Normal shocks with high upstream pressure

Author(s): William A. Sirignano

A normal compressive shock with upstream pressure from 10 to 500 bar is analyzed for density, enthalpy, entropy, and velocity with nitrogen, oxygen, argon, and carbon dioxide. New descriptions for sound speed, Prandtl’s relation, the Rankine-Hugoniot relation, and Riemann invariants are presented.

[Phys. Rev. Fluids 3, 093401] Published Mon Sep 17, 2018

### Visualization and analysis of magnetothermal convection of paramagnetic liquid in the Rayleigh-Benard model

Author(s): Syou Maki, Noriyuki Hirota, and Masayuki Hagiwara

We examined the heat transfer of magnetothermal convection in a Rayleigh-Benard model (height 9.2 mm, vessel diameter 20 mm, aspect ratio 2.17). The working fluid was an aqueous gadolinium nitrate solution of 0.15 mol/kg (pH=4.52 at 305.5 K, paramagnetic substance). Not only the magnetic body force ...

[Phys. Rev. E 98, 033109] Published Wed Sep 12, 2018

### Rayleigh-Taylor turbulence with singular nonuniform initial conditions

Author(s): L. Biferale, G. Boffetta, A. A. Mailybaev, and A. Scagliarini

Three-dimensional direct numerical simulations of Rayleigh-Taylor turbulence with various initial unstable temperature distributions finds a modified self-similar mixing in the long term.

[Phys. Rev. Fluids 3, 092601(R)] Published Wed Sep 12, 2018

### Collisions of drops with an immiscible liquid jet

Author(s): Carole Planchette, Sylvain Petit, Hannes Hinterbichler, and Günter Brenn

The collisions of a drop stream with an immiscible jet are experimentally studied revealing the formation of several complex structures classified in four main regimes. When neither the drops nor the jet fragment,“drops in jet” are observed that could be hardened to produce advanced fibers.

[Phys. Rev. Fluids 3, 093603] Published Wed Sep 12, 2018

### Thermophoresis of Janus particles at large Knudsen numbers

Author(s): Tobias Baier, Sudarshan Tiwari, Samir Shrestha, Axel Klar, and Steffen Hardt

At large Knudsen numbers a Janus particle in a thermal gradient shows a preferred orientation. The interplay between rotational diffusion and thermophoretic motion is investigated.

[Phys. Rev. Fluids 3, 094202] Published Wed Sep 12, 2018