Physical Review Fluids
Author(s): S. Lejeune, T. Gilet, and L. Bourouiba
Liquid sheet fragmentation is ubiquitous in nature and may shape phenomena such as the rain-induced propagation of foliar diseases. An experimental study investigates the formation and fragmentation of an asymmetric liquid sheet upon impact of a drop close to the edge of a solid substrate.
[Phys. Rev. Fluids 3, 083601] Published Tue Aug 07, 2018
Evolution of anisotropy in direct numerical simulations of MHD turbulence in a strong magnetic field on elongated periodic domains
Author(s): X. M. Zhai and P. K. Yeung
Time development (from top to bottom) of vortical structures (in red) in background of low vorticity (blue) in planar cross-sections of turbulence subjected to magnetic field on an elongated domain of aspect ratio 8, at 16384×20482 grid resolution.
[Phys. Rev. Fluids 3, 084602] Published Tue Aug 07, 2018
Author(s): Kosuke Osawa and Javier Jiménez
The effects of the ambiguity in the definition of the Reynolds stresses to the coherent structures in wall turbulence are studied. It is confirmed that sweeps, ejections, and rollers are robust features of the flow.
[Phys. Rev. Fluids 3, 084603] Published Tue Aug 07, 2018
Author(s): F. H. H. Al Mukahal, B. R. Duffy, and S. K. Wilson
The general parametric solution for the steady unidirectional flow of a thin rivulet of a generalized Newtonian fluid is obtained and illustrated for Carreau and Ellis fluids. In particular, the solution is used to describe the behavior of a rivulet of a strongly shear-thinning Ellis fluid.
[Phys. Rev. Fluids 3, 083302] Published Mon Aug 06, 2018
Turbulent magnetohydrodynamic flow in a square duct: Comparison of zero and finite magnetic Reynolds number cases
Author(s): Vinodh Bandaru, Thomas Boeck, and Jörg Schumacher
The effect of finite magnetic Reynolds numbers (Rm∼102) on MHD flow in a square duct was studied using direct numerical simulations. The structure of the secondary mean flow is modified significantly and the streamwise anisotropy is strongly enhanced away from the boundary layers.
[Phys. Rev. Fluids 3, 083701] Published Mon Aug 06, 2018
Numerical study of the effects of chemical dispersant on oil transport from an idealized underwater blowout
Author(s): Bicheng Chen, Di Yang, Charles Meneveau, and Marcelo Chamecki
To investigate how chemical dispersant impacts the transport of oil slicks such as the one from the Deepwater Horizon, a multiscale large-eddy simulation approach is used to show that the breakup of the oil slick into small droplets changes the mean transport direction and horizontal spread of the oil plume.
[Phys. Rev. Fluids 3, 083801] Published Mon Aug 06, 2018
Author(s): Simona Colabrese, Kristian Gustavsson, Antonio Celani, and Luca Biferale
A reinforcement learning algorithm is applied to find quasi-optimal policies for buoyancy control of inertial probes/particles in order to avoid trapping and to reach specific regions when navigating in complex two- and three-dimensional flows.
[Phys. Rev. Fluids 3, 084301] Published Mon Aug 06, 2018
Author(s): N. A. K. Doan, N. Swaminathan, P. A. Davidson, and M. Tanahashi
Scale locality of the energy cascade is demonstrated using direct numerical simulations data of homogeneous isotropic turbulence with Taylor microscale Reynolds numbers ranging from 37 to 1131. The range of influential scales for this scale locality is found to be independent of Reynolds number.
[Phys. Rev. Fluids 3, 084601] Published Mon Aug 06, 2018
Author(s): Juan L. Aragones, Shahrzad Yazdi, and Alfredo Alexander-Katz
An investigation of the behavior of self-propelled particles in complex media finds a transition from thermal diffusion to collision-driven diffusion as the particle area fraction is increased. Collisions with passive particles increases the rotational diffusion of the self-propelled particles, leading to their “self-trapping.”
[Phys. Rev. Fluids 3, 083301] Published Thu Aug 02, 2018
Author(s): Xiaoliang He, Sourabh Apte, Kai Schneider, and Benjamin Kadoch
The physics of turbulent flow in porous media is explored in the Lagrangian frame. The evolution of curvature angles along the fluid trajectories reveals the multiscale nature of turbulence. The asymptotic value of the curvature angle quantifies the effect of geometric confinement on turbulence.
[Phys. Rev. Fluids 3, 084501] Published Thu Aug 02, 2018
Author(s): Elise Alméras, Frédéric Risso, Véronique Roig, Cécile Plais, and Frédéric Augier
A large-scale model for transport by secondary open wakes is proposed to describe the spatiotemporal evolution of the concentration field in a homogeneous bidimensional bubble swarm rising at high Reynolds number.
[Phys. Rev. Fluids 3, 074307] Published Tue Jul 31, 2018
Author(s): Andrea Montessori, Marco Lauricella, Sauro Succi, Elad Stolovicki, and David Weitz
Three-dimensional Lattice Boltzmann simulations contrast backflow from an external reservoir into a confined microchannel in a dripping mode where the drop breaks off towards the end of the microchannel with a jetting mode at higher flows with drop break off further downstream inside the reservoir.
[Phys. Rev. Fluids 3, 072202(R)] Published Mon Jul 30, 2018
Author(s): M. A. Bruning, M. Costalonga, S. Karpitschka, and J. H. Snoeijer
The coalescence of surfactant solutions on a substrate is studied. By varying both the contact angle of the droplets and their difference in surface tension, various regimes with distinct timescales of noncoalescence are identified.
[Phys. Rev. Fluids 3, 073605] Published Mon Jul 30, 2018
Author(s): S. Lyu and S. M. Taghavi
There is considerable research to improve the displacement efficiency in buoyant two-fluid flow systems, e.g., when a heavy fluid is injected to displace a light one from a pipe. Experiments show that a pipe rotation helps to completely remove the displaced fluid.
[Phys. Rev. Fluids 3, 074003] Published Mon Jul 30, 2018
Author(s): Benjamin Allen and Arshad Kudrolli
Internal imaging shows that a granular bed consolidates and creeps under the action of fluid flow well below the bedload transport critical rate. The bed is shown to be armored with a systematic increase in erosion threshold depending on the duration and strength of applied subcritical shear.
[Phys. Rev. Fluids 3, 074305] Published Mon Jul 30, 2018
Self-similarity and coarsening rate of a convecting bicontinuous phase separating mixture: Effect of the viscosity contrast
Author(s): Hervé Henry and György Tegze
A computational study shows that the viscosity contrast between the two phases of a multiphase fluid induces noticeable morphological changes to the geometry of the two phases during self-similar coarsening. Quantitative measures are specified.
[Phys. Rev. Fluids 3, 074306] Published Mon Jul 30, 2018
Author(s): Jean-Philippe Boucher, Romain Labbé, Christophe Clanet, and Michael Benzaquen
We present a minimal approach to address the problem of ship hull optimization, and compare our theoretical results with existing data. We show that optimal hull aspect ratios result from a subtle balance between wave drag, pressure drag, and skin friction.
[Phys. Rev. Fluids 3, 074802] Published Mon Jul 30, 2018
Author(s): M. A. Gallis, J. R. Torczynski, N. P. Bitter, T. P. Koehler, S. J. Plimpton, and G. Papadakis
Simulations of a gas in a Minimal Couette unit at Re=500 using Direct Simulation Monte Carlo, a molecular method enforcing molecular chaos for gas-molecule collisions, reproduces the turbulence from DNS. Thus molecular chaos does not prevent development of long-range correlations in turbulence.
[Phys. Rev. Fluids 3, 071402(R)] Published Thu Jul 26, 2018
Author(s): Thomasina V. Ball and Jerome A. Neufeld
Transient spreading of a viscous fluid beneath an adhered elastic sheet is controlled by the tip dynamics. Spreading occurs in two dynamical regimes: viscosity dominant and adhesion dominant. Experiments with elastic sheets made of PDMS confirm these regimes and the emergence of a vapor tip.
[Phys. Rev. Fluids 3, 074101] Published Thu Jul 26, 2018
Oscillatory solutothermal convection-driven evaporation kinetics in colloidal nanoparticle-surfactant complex fluid pendant droplets
Author(s): A. R. Harikrishnan, Purbarun Dhar, Sateesh Gedupudi, and Sarit K. Das
Evaporation kinetics of surfactant-infused nanocolloidal droplets are studied using the pendant mode to understand the pure physics of evaporation in such complex fluids. Oscillatory solute-thermal convective currents are found to be responsible for evaporation rate enhancement in these complex fluids.
[Phys. Rev. Fluids 3, 073604] Published Wed Jul 25, 2018