Latest papers in fluid mechanics
Author(s): Vaseem A. Shaik and Arezoo M. Ardekani
In this work we analyze the velocity of a swimming sheet near a plane surfactant-laden interface by assuming the Reynolds number and the sheet's deformation to be small. We observe a nonmonotonic dependence of the sheet's velocity on the Marangoni number (Ma) and the surface Péclet number (Pes). For...
[Phys. Rev. E 99, 033101] Published Fri Mar 01, 2019
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
This paper determines analytically the velocity field induced by a configuration of linked vortices, with the aim of finding the translational velocity of such a configuration. The linked-vortex configuration consists of two vortices; the vortices are thin tubes of circular cross section lying on the surface of an immaterial torus of small aspect ratio [math] (where r1 is the cross section radius of a torus and r0 is its centerline radius). The induced velocity field has been found based on the vector potential associated with the Biot-Savart law by using a multipolar expansion; the comparison of this field with the material condition on the surface of the vortices allows one to calculate the translational velocity. The solution obtained retains effects to first order at the multipolar expansion, which corresponds to the effects the vortex curvature has at the vorticity distribution on its cross section. This solution agrees with the numerical results in the range of 2%. The method presented is generalized to the case of n linked vortices.
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): R. M. Velasco and F. J. Uribe
In this work we present a phenomenological model to look for a better understanding of the shock-wave structure in dilute monatomic gases. The model is based on the principles of linear irreversible thermodynamics, where we have been aware of the flow anisotropy caused by the shock-wave propagation....
[Phys. Rev. E 99, 023114] Published Wed Feb 27, 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): Isabel Mercader, Oriol Batiste, Arantxa Alonso, and Edgar Knobloch
We analyze the effect of a small inclination on the well-studied problem of two-dimensional binary fluid convection in a horizontally extended closed rectangular box with a negative separation ratio, heated from below. The horizontal component of gravity generates a shear flow that replaces the moti...
[Phys. Rev. E 99, 023113] Published Tue Feb 26, 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
Exact, approximate, and hybrid treatments of viscous Rayleigh-Taylor and Richtmyer-Meshkov instabilities
Author(s): Karnig O. Mikaelian
We consider Rayleigh-Taylor and Richtmyer-Meshkov instabilities at the interface between two fluids, one or both of which may be viscous. We derive exact analytic expressions for the amplitude η(t) in the linear regime when only one of the fluids is viscous. The more general case is solved numerical...
[Phys. Rev. E 99, 023112] Published Mon Feb 25, 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