Physical Review Fluids
Author(s): Kaitlyn Hood and Marcus Roper
In microfluidic devices, inertia drives particles to focus on a streamline and form one-dimensional microfluidic crystals. Asymptotic theory for the pairwise particle interactions shows that particles assemble into stable equilibria, and the dynamics are analogous to the motion of a damped spring.
[Phys. Rev. Fluids 3, 094201] Published Wed Sep 05, 2018
Author(s): Gerardo Ruiz Chavarria, Patrice Le Gal, and Michael Le Bars
In an experimental investigation, water surface waves are focused at the Huygens’ cusp of a parabolic wave maker. Small amplitude waves behave linearly and similarly to light waves, following the diffraction laws. Large amplitude nonlinear waves are distorted by a large scale flow and focus before the expected cusp.
[Phys. Rev. Fluids 3, 094803] Published Wed Sep 05, 2018
Author(s): Yiran Zhang, Hadi Mohammadigoushki, Margaret Y. Hwang, and Susan J. Muller
Flow transitions in wormlike micelle solutions flowing around a microfluidic 90° bend are studied. Shear-banding properties of the solution correlate with the form of secondary flow, while the micelle morphology (linear vs branched) has little effect on the flow behavior.
[Phys. Rev. Fluids 3, 093301] Published Tue Sep 04, 2018
Author(s): Paola Leon Plata, Ying Liu, and Ludwig C. Nitsche
During sedimentation in a miscible, viscous liquid, polymeric drops self-assemble into a toroidal-spiral structure, which can be solidified by photoinitiated cross-linking. With a suitable arrangement three drops can be encapsulated, possibly enabling controlled release of a therapeutic drug cocktail.
[Phys. Rev. Fluids 3, 093601] Published Tue Sep 04, 2018
Author(s): Binod Sreenivasan and Subhajit Kar
To understand why the magnetic fields of many planets are axial dipoles, the evolution in time of a seed magnetic field is studied using a dynamo model. The field is shown to excite helical convection, and the timescale for the growth in convection matches that for dipole formation.
[Phys. Rev. Fluids 3, 093801] Published Tue Sep 04, 2018
Author(s): J. M. Floryan, S. Shadman, and M. Z. Hossain
A new analysis shows that the force required to maintain the relative movement of parallel plates is significantly reduced when these plates are heated in a spatially nonuniform manner.
[Phys. Rev. Fluids 3, 094101] Published Tue Sep 04, 2018
Inviscid simulations of expansion waves propagating into structured particle beds at low volume fractions
Author(s): Goran Marjanovic, Jason Hackl, Mrugesh Shringarpure, Subramanian Annamalai, Thomas L. Jackson, and S. Balachandar
We perform fully resolved simulations of expansion waves propagating into particle beds of varying volume fractions using the discontinuous Galerkin spectral element method. We validate state-of-the-art drag models and predict the final state of the particle bed using isentropic flow relations.
[Phys. Rev. Fluids 3, 094301] Published Tue Sep 04, 2018
Author(s): Francesco Romanò and Hendrik C. Kuhlmann
A numerical investigation shows that finite-size Lagrangian coherent structures result from bulk transport near Kolmogorov-Arnold-Moser tori and a dissipative effect that finite-size particles experience near the free surface.
[Phys. Rev. Fluids 3, 094302] Published Tue Sep 04, 2018
Author(s): Emil Varga, Jian Gao, Wei Guo, and Ladislav Skrbek
Intermittency of quasiclassical quantum turbulence in superfluid 4He is experimentally found to be temperature dependent and enhanced for a range of temperatures compared to classical turbulence, in contrast with nearly flow-independent intermittency of turbulence in classical fluids.
[Phys. Rev. Fluids 3, 094601] Published Tue Sep 04, 2018
Theoretical framework to analyze the combined effect of surface tension and viscosity on the damping rate of sloshing waves
Author(s): Francesco Viola and François Gallaire
A dynamic meniscus affects viscous dissipation of oscillating contact lines. A theoretical proposal, marrying viscous sloshing dynamics and a realistic contact line model including contact angle hysteresis, finds that both the wave damping rate and frequency increase at small amplitude.
[Phys. Rev. Fluids 3, 094801] Published Tue Sep 04, 2018
Author(s): Claudio Falcón and Edgar Knobloch
Two-dimensional turbulence can generate shallow water waves. These waves carry information about the structure of their turbulent source. A theoretical calculation of the wave spectrum is proposed, which may lead to an insightful way to characterize turbulence.
[Phys. Rev. Fluids 3, 094802] Published Tue Sep 04, 2018
Author(s): Ruifeng Hu and Xiaojing Zheng
In a new study, the critical Reynolds number for the emergence of outer motions in turbulent channel flows is determined to be Reτ≈110. The growing significance of outer motions is obtained by subtracting the inner contributions from the total at low to moderate Reynolds numbers.
[Phys. Rev. Fluids 3, 084607] Published Fri Aug 31, 2018
Author(s): Gioele Balestra, David Minh-Phuc Nguyen, and François Gallaire
The Rayleigh-Taylor instability of a thin viscous film coating the inside of a spherical substrate is studied. The instability properties are investigated by performing a linear optimal transient growth analysis. The pattern formation is further analyzed using nonlinear numerical simulations.
[Phys. Rev. Fluids 3, 084005] Published Thu Aug 30, 2018
Author(s): James E. McClure, Ryan T. Armstrong, Mark A. Berrill, Steffen Schlüter, Steffen Berg, William G. Gray, and Cass T. Miller
It is shown that the geometric state of fluids within porous media can be expressed in terms of a relationship that links the fluid volume, surface area, mean curvature, and Euler characteristic. The relationship is able to accurately model complex changes in fluid connectivity and structure.
[Phys. Rev. Fluids 3, 084306] Published Thu Aug 30, 2018
Author(s): Jiacai Lu and Gretar Tryggvason
Multifluid flows with changes in the topology of the interface separating the different fluids, in a turbulent vertical channel, are examined using direct numerical simulations. The results show how different surface tension changes the evolution of the flow and the interface topology.
[Phys. Rev. Fluids 3, 084401] Published Thu Aug 30, 2018
Author(s): Jiajia Zhou and Masao Doi
Exponential thinning of a viscoelastic filament is analyzed using the Onsager variational principle.
[Phys. Rev. Fluids 3, 084004] Published Wed Aug 29, 2018
Author(s): Maxime Bassenne, Parviz Moin, and Javier Urzay
The preferential concentration of inertial particles in isotropic turbulence is studied using wavelets, enabling the joint scale-space analysis of the flow field of the carrier phase, the concentration field of the dispersed phase, and interphase conditioned statistics.
[Phys. Rev. Fluids 3, 084304] Published Wed Aug 29, 2018
Author(s): Yayun Wang and Andrea Prosperetti
Resolved simulations of turbulent flow past a fixed planar array of cold particles show the fundamental differences between velocity and temperature fields, cast light on the limitations of the point particle model and illustrate the mechanism by which turbulence disrupts the thermal wakes.
[Phys. Rev. Fluids 3, 084305] Published Wed Aug 29, 2018
Derivation of a realistic forcing term to reproduce the turbulent characteristics of round jets on the centerline
Author(s): Kyupaeck Jeff Rah, Chandru Dhandapani, and Guillaume Blanquart
Turbulence forcing techniques are often required in the numerical simulation of turbulent flows. A novel forcing technique, based on physics, is devised to reproduce the centerline turbulent characteristics of round jets in a triply periodic box.
[Phys. Rev. Fluids 3, 084606] Published Wed Aug 29, 2018
Author(s): JiaCheng Hu and Sean D. Peterson
An investigation of the interaction of a vortex ring colliding with a coaxially aligned aperture, which extends the classical problem of a vortex ring impacting a solid wall, examines the behaviors of near-wall vortices in the proximity of a structural discontinuity (aperture tip).
[Phys. Rev. Fluids 3, 084701] Published Wed Aug 29, 2018