Physical Review Fluids
Author(s): Tiras Y. Lin and Eric S. G. Shaqfeh
A solute flowing in a pressure-driven channel flow experiences an enhanced effective axial dispersion coefficient due to the transverse velocity gradients. An investigation shows how this phenomenon, known as Taylor dispersion, is affected by cross flow and mass transfer at the wall.
[Phys. Rev. Fluids 4, 034501] Published Fri Mar 01, 2019
Author(s): Amihai Horesh, Daniel Khaikin, Mackenzie Karnilaw, Anna Zigelman, and Ofer Manor
In experiments a surface acoustic wave at 20 Mhz propagating down a vertical surface induces a liquid film to climb up the surface against gravity.
[Phys. Rev. Fluids 4, 022001(R)] Published Thu Feb 28, 2019
Numerical investigation of the collapse of a static bubble at the free surface in the presence of neighbors
Author(s): Digvijay Singh and Arup Kumar Das
Formation of a liquid jet and drop as a consequence of the bursting of a bubble in symmetric and asymmetric neighborhoods is modeled numerically. We find that unbalanced interaction of neighbors forces the jet and drop to bend towards the absent bubbles.
[Phys. Rev. Fluids 4, 023602] Published Thu Feb 28, 2019
Author(s): Cees Haringa, Conrad de Jong, Duong A. Hoang, Luis M. Portela, Chris R. Kleijn, Michiel T. Kreutzer, and Volkert van Steijn
Long droplets entering a microfluidic T-junction get trapped below, and break beyond, a critical capillary number, which is determined theoretically and experimentally in this work.
[Phys. Rev. Fluids 4, 024203] Published Thu Feb 28, 2019
Author(s): Di Shen and Kang Ping Chen
The compressible Navier-Stokes equations already include the self-diffusion effect. Comparisons with 35 experiments show that the self-diffusion effect is too small to account for the mass flow rate enhancement in steady compressible gas flow through a microconduit in the slip flow regime.
[Phys. Rev. Fluids 4, 024202] Published Wed Feb 27, 2019
Low-dimensional representations and anisotropy of model rotor versus porous disk wind turbine arrays
Author(s): Elizabeth H. Camp and Raúl Bayoán Cal
We experimentally compare wakes within three-bladed rotor and porous disk wind turbine arrays using PIV measurements and proper orthogonal decomposition. Disparities between rotors and disks with important implications for wind turbine simulations is found.
[Phys. Rev. Fluids 4, 024610] Published Wed Feb 27, 2019
Author(s): Katsunori Yoshimatsu and Yukio Kaneda
A certain homogeneous fully developed turbulence, which was initially reflection asymmetric at large scales, is studied theoretically and numerically. It is shown that the turbulence does not relax to any reflection symmetric state, even in the energy containing range.
[Phys. Rev. Fluids 4, 024611] Published Wed Feb 27, 2019
Author(s): Marco De Paoli, Francesco Zonta, and Alfredo Soldati
RT instability and convection in confined porous media is examined via DNS. Interactions between gravity and diffusion produce efficient fluid mixing, and a superlinear asymptotic growth of the mixing rate is observed and modeled for the first time. Potential geophysical applications are envisioned.
[Phys. Rev. Fluids 4, 023502] Published Tue Feb 26, 2019
Author(s): Sheng Chen, Shuiqing Li, and Jeffrey S. Marshall
Agglomeration of adhesive particles in turbulence is investigated. The size distribution of early-stage agglomerates follows a unified exponential scaling. A new agglomeration kernel containing information about the fractal structure of agglomerates and the sticking probability is constructed.
[Phys. Rev. Fluids 4, 024304] Published Tue Feb 26, 2019
Author(s): Zenghao Zhu, Sheldon Weinbaum, and Qianhong Wu
Lessons learned from the motion of red cells in capillaries are applied to a novel experimental study of soft porous lubrication, which conclusively demonstrates a dramatic decrease of friction coefficient with tremendously enhanced pore pressure as a planar board glides over a soft porous layer.
[Phys. Rev. Fluids 4, 024305] Published Tue Feb 26, 2019
Author(s): T. R. Kirkpatrick and J. K. Bhattacherjee
A new hydrodynamic instability in driven active matter is discussed. It is similar to the convective instability that occurs in passive fluids, but differs in several important ways. In particular, the transition to turbulence in the active matter system is expected to be novel.
[Phys. Rev. Fluids 4, 024306] Published Tue Feb 26, 2019
Author(s): Nan Xue, Sepideh Khodaparast, and Howard A. Stone
Pouring a liquid down into a container of a denser liquid creates a fountain. We measure the penetration depth of such fountains and characterize the mixing based on the Reynolds (Re) and Froude (Fr) numbers.
[Phys. Rev. Fluids 4, 024501] Published Tue Feb 26, 2019
Author(s): Aurore Naso
Homogeneous rotating turbulence structure is investigated by analyzing instantaneous statistics of the scale-dependent perceived velocity gradient tensor. Rotation is shown to suppress some alignment properties of isotropic turbulence, decreasing enstrophy production and strain production rates.
[Phys. Rev. Fluids 4, 024609] Published Mon Feb 25, 2019
Author(s): Axel Brandenburg, Tina Kahniashvili, Sayan Mandal, Alberto Roper Pol, Alexander G. Tevzadze, and Tanmay Vachaspati
It is shown that decaying helical turbulence amplifies a weak magnetic field, which then itself becomes helical. However, it displays a transient behavior different from any other helical or nonhelical magnetic decaying field in a parametric representation between the temporal scaling exponents p(t) and q(t).
[Phys. Rev. Fluids 4, 024608] Published Fri Feb 22, 2019
Author(s): Paul A. Jarvis, Heidy M. Mader, Herbert E. Huppert, Katharine V. Cashman, and Jon D. Blundy
Experiments on the low-Reynolds number settling of a sphere through a fluid interface focus on the effect of the viscosity ratio and Bond number on the shape of the sphere position curve as a function of time, whether sinking occurs through a tailing or film drainage mode and the sinking timescale.
[Phys. Rev. Fluids 4, 024003] Published Wed Feb 20, 2019
Author(s): M. Rubio, A. Ponce-Torres, E. J. Vega, M. A. Herrada, and J. M. Montanero
High speed observations are made of the pinching off of a pendant drop.
[Phys. Rev. Fluids 4, 021602(R)] Published Tue Feb 19, 2019
Author(s): S. Musacchio and G. Boffetta
Three-dimensional numerical simulations of forced turbulence in a thin layer show the transfer from the forcing to larger scales is by two-dimensional modes, and to smaller scales by three-dimensional modes, the latter providing a viscosity-independent dissipation.
[Phys. Rev. Fluids 4, 022602(R)] Published Tue Feb 19, 2019
Author(s): Sparsh Sharma and Ennes Sarradj
A genetic algorithm is used to optimally populate a random flow with two-dimensional Gaussian-shaped vortices subject to certain constraints.
[Phys. Rev. Fluids 4, 022701(R)] Published Tue Feb 19, 2019
Author(s): Shunlin Tang, Robert A. Antonia, Lyazid Djenidi, and Yu Zhou
Analytical considerations, based on the Navier-Stokes equations, which take into account the finite Reynolds number effect, together with all available experimental laboratory data, confirm a tendency towards the universal predictions of K41 as the Reynolds number continues to increase.
[Phys. Rev. Fluids 4, 024607] Published Tue Feb 19, 2019
Assessment of two vortex formulations for computing forces of a flapping foil at high Reynolds numbers
Author(s): A. Martín-Alcántara and R. Fernandez-Feria
Impulse-based vortex formulas are found appropriate for computing propulsion forces from experiments only when the vortices remain close to the moving foil, as in starting motions or in hovering flight, but are inaccurate in forward flight or swimming, where projection methods perform much better.
[Phys. Rev. Fluids 4, 024702] Published Tue Feb 19, 2019