# Latest papers in fluid mechanics

### Multiscaling analysis of the mean thermal energy balance equation in fully developed turbulent channel flow

Author(s): Tie Wei

Properly accounting for the intricate Prandtl number dependence in different layers of turbulent channel flows, a multiscaling analysis is developed for the mean thermal energy balance (MHB) equations. A formal analogy is established between the MHB equation and the mean momentum balance equation.

[Phys. Rev. Fluids 3, 094608] Published Fri Sep 28, 2018

### Solutal convection in porous media: Comparison between boundary conditions of constant concentration and constant flux

Author(s): Mohammad Amin Amooie, Mohamad Reza Soltanian, and Joachim Moortgat

We numerically examine solutal convection in porous media, driven by the dissolution of carbon dioxide (CO2) into water—an effective mechanism for CO2 storage in saline aquifers. Dissolution is associated with slow diffusion of free-phase CO2 into the underlying aqueous phase followed by density-dri...

[Phys. Rev. E 98, 033118] Published Thu Sep 27, 2018

### Modeling sphere suspension microstructure and stress

Author(s): J. J. J. Gillissen and H. J. Wilson

We develop a model for the microstructure and the stress, in dense suspensions of non-Brownian, perfectly smooth spheres at vanishing particle Reynolds number. These quantities are defined in terms of the second-order moment a of the distribution function of the orientation unit vector between hydro...

[Phys. Rev. E 98, 033119] Published Thu Sep 27, 2018

### Dynamics of a simple model microswimmer in an anisotropic fluid: Implications for alignment behavior and active transport in a nematic liquid crystal

Author(s): Abdallah Daddi-Moussa-Ider and Andreas M. Menzel

Simple model microswimmers in an oriented uniaxially anisotropic fluid, such as a nematic liquid crystal, can show rich alignment behavior due to purely hydrodynamic effects. The type of propulsion mechanism and the relative magnitudes of the different involved viscosities play a crucial role.

[Phys. Rev. Fluids 3, 094102] Published Thu Sep 27, 2018

### Mean kinetic energy replenishment mechanisms in vertical-axis wind turbine farms

Author(s): Seyed Hossein Hezaveh and Elie Bou-Zeid

We study mean kinetic energy replenishment in a clustered farm of vertical axis wind turbines using an actuator line model in a large eddy simulation. We find that clustered designs are benefical for improving overall performance but suggest that irregular designs may have even more promise.

[Phys. Rev. Fluids 3, 094606] Published Wed Sep 26, 2018

### Formation number of confined vortex rings

Author(s): I. Danaila, F. Luddens, F. Kaplanski, A. Papoutsakis, and S. S. Sazhin

The formation number of confined vortex rings is studied using direct numerical simulations. The structure of the vortex ring at pinch-off depends on the injection program and the confinement ratio. The value of the formation time is predicted using a model for the viscous confined vortex ring.

[Phys. Rev. Fluids 3, 094701] Published Wed Sep 26, 2018

### Spectral energy cascade and decay in nonlinear acoustic waves

Author(s): Prateek Gupta and Carlo Scalo

We present a numerical and theoretical investigation of the nonlinear spectral energy cascade of decaying finite-amplitude planar acoustic waves in a single-component ideal gas at standard temperature and pressure. We analyze various one-dimensional canonical flow configurations: a propagating trave...

[Phys. Rev. E 98, 033117] Published Tue Sep 25, 2018

### Diffuse interface model to simulate the rise of a fluid droplet across a cloud of particles

Author(s): Gregory Lecrivain, Yuki Kotani, Ryoichi Yamamoto, Uwe Hampel, and Takashi Taniguchi

We simulate a fluid droplet with suspended particles rising in another fluid with a diffuse interface model in which phase boundaries are replaced with smooth spreading interfaces. We find that at low Reynolds number the droplet terminal velocity decreases exponentially with particle concentration.

[Phys. Rev. Fluids 3, 094002] Published Tue Sep 25, 2018

### Current-voltage response for unipolar funnel-shaped nanochannel diodes

Author(s): Yoav Green

Permselective nanochannels can rectify the electric current transported through them similar to solid-state diodes. The rectification is due to symmetry breaking related to distribution of the nanochannels’ surface charge as well as the geometry. Thus far, most of the works related to the asymmetric...

[Phys. Rev. E 98, 033114] Published Mon Sep 24, 2018

### Surface modes with controlled axisymmetry triggered by bubble coalescence in a high-amplitude acoustic field

Author(s): Sarah Cleve, Matthieu Guédra, Claude Inserra, Cyril Mauger, and Philippe Blanc-Benon

When two bubbles encounter each other in a moderate ultrasound field they coalesce into a single bubble that shows purely spherical oscillations. For a sufficiently large acoustic field, this coalescence can lead to sustained nonspherical oscillations of the resulting bubble. We experimentally captu...

[Phys. Rev. E 98, 033115] Published Mon Sep 24, 2018

### 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