Physical Review Fluids
Predicting transition ranges to fully turbulent viscous boundary layers in low Prandtl number convection flows
Author(s): Janet D. Scheel and Jörg Schumacher
Characteristic properties of turbulent Rayleigh-Bénard convection in the bulk and the boundary layers are summarized for a wide range of Rayleigh and Prandtl numbers, with a specific emphasis on low-Prandtl-number convection.
[Phys. Rev. Fluids 2, 123501] Published Wed Dec 06, 2017
Effect of shear thinning on superhydrophobic slip: Perturbative corrections to the effective slip length
Author(s): Darren Crowdy
We find expressions for the change in hydrodynamic slip length when a weakly shear-thinning fluid flows longitudinally, or transversely, over a periodic array of flat, unidirectional no-shear slots from a modified reciprocal theorem of Stokes flow and exact solutions for a Newtonian fluid.
[Phys. Rev. Fluids 2, 124201] Published Wed Dec 06, 2017
Author(s): Bardia Hejazi, Bernhard Mehlig, and Greg A. Voth
When fibers are advected in a fluid flow, they organize into patterns dominated by scar lines across which the fiber orientation rotates by π. An exploration of the topology of the fiber orientation field in a 2D chaotic flow shows that scar lines form by a process of fluid stretching reversal.
[Phys. Rev. Fluids 2, 124501] Published Wed Dec 06, 2017
Giant deviation of a relaxation time from generalized Newtonian theory in discontinuous shear thickening suspensions
Author(s): Rijan Maharjan and Eric Brown
Experimental study on discontinuous shear thickening fluids reveals that the relaxation times agree with a generalized Newtonian model for lower weight fractions. At high weight fractions, however, the relaxation times disagree by up to 4 orders of magnitude.
[Phys. Rev. Fluids 2, 123301] Published Tue Dec 05, 2017
Author(s): Joram Wasserfall, Patric Figueiredo, Reinhold Kneer, Wilko Rohlfs, and Philipp Pischke
Superhydrophobic surfaces are designated by a low wettability that gives rise to self-cleaning. This study analyses the fluid dynamics of self-propelled droplet jumping upon binary unequal sized droplet coalescence with three-dimensional simulations.
[Phys. Rev. Fluids 2, 123601] Published Mon Dec 04, 2017
Author(s): David E. S. Breakey, Peter Jordan, André V. G. Cavalieri, Petrônio A. Nogueira, Olivier Léon, Tim Colonius, and Daniel Rodríguez
Pressure fluctuations in unforced subsonic jets indicate the presence of linear wave packets in the near field. An interpretation in the resolvent framework shows that these signatures represent higher order near-field behavior that must be captured to obtain accurate far-field acoustic predictions.
[Phys. Rev. Fluids 2, 124601] Published Fri Dec 01, 2017
Author(s): Daniel P. Willen, Adam J. Sierakowski, Gedi Zhou, and Andrea Prosperetti
A method to coarse-grain the results of resolved simulations is described and used to demonstrate the presence of continuity waves in the simulations of 500–2000 particles suspended in an upward fluid flow. The results agree very well with the standard continuum theory of kinematic waves.
[Phys. Rev. Fluids 2, 114305] Published Thu Nov 30, 2017
Author(s): Nabil Abderrahaman-Elena and Ricardo García-Mayoral
Anisotropic permeable surfaces are proposed to reduce turbulent skin friction. The apparent streamwise slip induced reduces drag, while the spanwise one increases it. Transpiration can trigger the appearance of Kelvin-Helmholtz-like rollers, which limit the performance of the surface.
[Phys. Rev. Fluids 2, 114609] Published Thu Nov 30, 2017
Point force singularities outside a drop covered with an incompressible surfactant: Image systems and their applications
Author(s): Vaseem A. Shaik and Arezoo M. Ardekani
Image systems for Stokes flow singularities outside a drop covered with an incompressible surfactant are derived. They are used in finding the mobility matrix for two surfactant-laden drops of arbitrary sizes and the velocity of a microorganism outside a surfactant-covered drop.
[Phys. Rev. Fluids 2, 113606] Published Wed Nov 29, 2017
Author(s): Xi Xia, Chengming He, Dehai Yu, Jiaquan Zhao, and Peng Zhang
The formation of the mushroomlike jet emerging after droplet coalescence is deciphered by studying the growth and detachment of the main vortex ring. A Reynolds number calculated based on the main vortex ring is shown to provide a unified formation criterion for such internal jets.
[Phys. Rev. Fluids 2, 113607] Published Wed Nov 29, 2017
Author(s): Céline Guervilly and David W. Hughes
Large-scale features in rotating convection can take the form of either jets or coherent vortices. Numerical simulations of horizontally anisotropic planar rotating convection reveal the interaction between jets and vortices and show how these typically co-exist.
[Phys. Rev. Fluids 2, 113503] Published Tue Nov 28, 2017
Author(s): X. Lin, L. E. Johns, and R. Narayanan
We show that the critical point of a static pendent drop pinned at a curve under volume or pressure control is bounded independent of the curve symmetry. If the curve is symmetric and the base drop shape known, the critical points for symmetric or asymmetric instability are found.
[Phys. Rev. Fluids 2, 113605] Published Mon Nov 27, 2017
Author(s): Ian Grooms
Spatially localized stochastic forcing generates turbulent dynamics in a 2D fluid with a uniform background vorticity gradient, enabling a study of the turbulent transport of kinetic energy.
[Phys. Rev. Fluids 2, 113801] Published Mon Nov 27, 2017
Author(s): Mijail Febres and Dominique Legendre
Stokes flow solutions are studied in the corner made by a fluid-fluid interface. The existence of an infinite series of Moffatt vortices is examined.
[Phys. Rev. Fluids 2, 114002] Published Mon Nov 27, 2017
Author(s): Pawel Baj and Oliver R. H. Buxton
The near wake of a multiscale array of bars is studied in search of features of multiscale-generated turbulence. Additional velocity modes are found on top of the regular sheddings close to the various wakes’ intersections. The energy budget of the triple-decomposed velocity yields further insight.
[Phys. Rev. Fluids 2, 114607] Published Mon Nov 27, 2017
Author(s): P. Aillaud, L. Y. M. Gicquel, and F. Duchaine
Wall curvature effect for an impinging jet flow is investigated. The concave curvature is found to reduce the heat transfers at the wall. A detailed analysis of the mechanisms driving the heat transfers shows the impact of the stabilization effect present in the wall jet over the curved surface.
[Phys. Rev. Fluids 2, 114608] Published Mon Nov 27, 2017
Author(s): J. Mak, S. D. Griffiths, and D. W. Hughes
The interaction of vortices with a magnetic field is studied using both theoretical scaling arguments and numerical simulations. Even very weak background fields can be amplified to such a strength that the vortices are severely disrupted or even destroyed by the Lorentz force.
[Phys. Rev. Fluids 2, 113701] Published Wed Nov 22, 2017
Author(s): Jerome Duplat, Mathieu Grandemange, and Cedric Poulain
The local mass flux around a CO2 gas bubble dissolving against a wall are experimentally determined and an analytical model is presented. Rayleigh number is shown to be crucial in estimating the condensing or evaporating rates of bubbles or droplets deposited on a flat surface.
[Phys. Rev. Fluids 2, 114001] Published Wed Nov 22, 2017
Heterogeneous drying and nonmonotonic contact angle dynamics in concentrated film-forming latex drops
Author(s): Subhalakshmi Kumar, Joshua S. Katz, and Charles M. Schroeder
A nonmonotonic decay in contact angle was observed in drying suspensions of concentrated film-forming latexes. Heterogeneity in film topologies is associated with particle packing at the droplet edge. The process is quantitatively modeled by considering dilational stresses in a viscoelastic solid.
[Phys. Rev. Fluids 2, 114304] Published Wed Nov 22, 2017
Author(s): Avinash Vaidheeswaran, Franklin Shaffer, and Balaji Gopalan
Particle velocity fluctuations in a large-scale circulating fluidized bed are observed to be anisotropic and non-Maxwellian. Interfacial drag acting on high-density configurations lead to excursions resulting in Levy flight of particles.
[Phys. Rev. Fluids 2, 112301(R)] Published Tue Nov 21, 2017