Physical Review Fluids
Erratum: Linearized propulsion theory of flapping airfoils revisited [Phys. Rev. Fluids <b>1</b>, 084502 (2016)]
Author(s): R. Fernandez-Feria
[Phys. Rev. Fluids 2, 119901] Published Tue Nov 21, 2017
Combined influence of inertia, gravity, and surface tension on the linear stability of Newtonian fiber spinning
Author(s): M. Bechert and B. Scheid
A study on the draw resonance instability in Newtonian fiber spinning and the influence of inertia, gravity, and surface tension is presented. The results are evaluated using stability maps of highly practical relevance and various dynamical regimes are revealed and discussed.
[Phys. Rev. Fluids 2, 113905] Published Mon Nov 20, 2017
Author(s): J. C. Salevan, Abram H. Clark, Mark D. Shattuck, Corey S. O'Hern, and Nicholas T. Ouellette
Analyzing grain motion statistics shows that, in the presence of turbulence, it is not possible to unambiguously distinguish between mobile and static grains near the onset of sediment transport. Instead we treat these grains together and fit their statistics with a two-phase mixture model.
[Phys. Rev. Fluids 2, 114302] Published Mon Nov 20, 2017
Author(s): Mac Panah, François Blanchette, and Shilpa Khatri
The time it takes porous particles, like marine snow, to reach the ocean floor depends on the density of the water they encounter. The density of a particle’s inner fluid changes on a diffusive time scale, which can slow its progress to a crawl. A new study quantifies the resulting delays numerically.
[Phys. Rev. Fluids 2, 114303] Published Mon Nov 20, 2017
Author(s): Julian Kappler, Shamit Shrivastava, Matthias F. Schneider, and Roland R. Netz
A nonlinear fractional wave equation for 2D sound waves at interfaces is derived from first principles. Numerical solutions of the equation reproduce experimental key features, namely an abrupt increase in range accompanied by a slight increase in wave velocity at a threshold excitation amplitude.
[Phys. Rev. Fluids 2, 114804] Published Mon Nov 20, 2017
Asymptotic far-field behavior of macroscopic quantities in a problem of slow uniform rarefied gas flow past a sphere
Author(s): Satoshi Taguchi and Toshihiro Suzuki
The asymptotic far-field behavior of macroscopic quantities in a problem of slow uniform rarefied gas flow past a sphere is investigated for the purpose of acquiring a function occurring in the second-order drag. The thermal force in the problem of thermophoresis of a sphere is also discussed.
[Phys. Rev. Fluids 2, 113401] Published Fri Nov 17, 2017
Effect of Marangoni stress on the bulk rheology of a dilute emulsion of surfactant-laden deformable droplets in linear flows
Author(s): Shubhadeep Mandal, Sayan Das, and Suman Chakraborty
The impact of surfactant redistribution along a droplet surface on the deformation and suspension rheology of a dilute droplet emulsion suspended in a linear flow field is analyzed. The study find that an increase in surfactant convection augments droplet deformation and emulsion effective viscosity.
[Phys. Rev. Fluids 2, 113604] Published Fri Nov 17, 2017
Author(s): Léopold Shaabani-Ardali, Denis Sipp, and Lutz Lesshafft
A numerical method for the computation of unstable limit-cycle flows is presented. This technique, straightforward to implement, filters nonperiodic components with a time-delayed feedback. It is shown for the examples of an axisymmetric forced jet subject to pairing and a 3D lid-driven cavity.
[Phys. Rev. Fluids 2, 113904] Published Fri Nov 17, 2017
Author(s): Quentin Aubourg, Antoine Campagne, Charles Peureux, Fabrice Ardhuin, Joel Sommeria, Samuel Viboud, and Nicolas Mordant
Water surface deformation is reconstructed by stereoscopic imaging to develop a high-order statistical analysis of randomly forced turbulent gravity waves. Resonant wave coupling is investigated and laboratory data compared to field measurements in the Black Sea.
[Phys. Rev. Fluids 2, 114802] Published Fri Nov 17, 2017
Author(s): C. Brouzet, I. N. Sibgatullin, E. V. Ermanyuk, S. Joubaud, and T. Dauxois
Physical effects scale differently with size. As a necessary preliminary step toward geophysically significant extrapolations, an experimental and numerical study of the scale effects in internal wave attractors in linear and nonlinear regimes is made, showing two different scalings for the beam width.
[Phys. Rev. Fluids 2, 114803] Published Fri Nov 17, 2017
Author(s): Timothée Mouterde, Thanh-Vinh Nguyen, Hidetoshi Takahashi, Christophe Clanet, Isao Shimoyama, and David Quéré
In an investigation of how drops merging on a nonwetting surface jump off the surface, the takeoff velocity is measured and modeled.
[Phys. Rev. Fluids 2, 112001(R)] Published Thu Nov 16, 2017
Author(s): Andrew K. Balin, Andreas Zöttl, Julia M. Yeomans, and Tyler N. Shendruk
A rotating helical pump actively stretches nearby polymers and draws them inwards as demonstrated in Stokesian dynamics simulations. The effect of such an interaction hinders the helix, increasing the amount of work required to maintain constant rotation.
[Phys. Rev. Fluids 2, 113102] Published Thu Nov 16, 2017
Author(s): Prakash Mohan, Nicholas Fitzsimmons, and Robert D. Moser
New work characterizes the chaotic nature of isotropic turbulence using Lyapunov exponents and determines how they scale with Reynolds number. The scaling results suggest that instabilities could act on sub-Kolmogorov scales at sufficiently high Reynolds numbers.
[Phys. Rev. Fluids 2, 114606] Published Thu Nov 16, 2017
Author(s): B. H. Burgess, D. G. Dritschel, and R. K. Scott
Numerical simulations of the decay of two-dimensional turbulence find new scalings for the distribution of the sizes of vortices and their strength, such that the time for vortices to cross the intervortex separation is independent of their size.
[Phys. Rev. Fluids 2, 114702] Published Thu Nov 16, 2017
Author(s): Olga Shishkina, Susanne Horn, Mohammad S. Emran, and Emily S. C. Ching
A thermal boundary layer equation that includes fluctuations is solved using a relation between the eddy thermal diffusivity and the stream function, and a closed-form expression for the mean temperature profiles in turbulent Rayleigh-Bénard convection is obtained for fluids with a general Prandtl number .
[Phys. Rev. Fluids 2, 113502] Published Wed Nov 15, 2017
Author(s): Neha Gawande, Y. S. Mayya, and Rochish Thaokar
A spherical drop charged beyond its Rayleigh limit ejects a significant fraction of its charge as a jet. Coupled hydrodynamics and electrostatics are used to find the charge loss in the low Re limit. Simulations show this is 39% of the initial charge, within the known experimental range of 20–50%.
[Phys. Rev. Fluids 2, 113603] Published Wed Nov 15, 2017
Author(s): Enrico Rinaldi, Ashish Patel, Philipp Schlatter, and Rene Pecnik
A linear stability analysis of the mean flow of turbulent channels with temperature-dependent density and viscosity predicts modified energy growth rate and threshold for secondary instability of streaks consistent with direct numerical simulation observations. Semilocal scaling parametrizes the effect of properties.
[Phys. Rev. Fluids 2, 113903] Published Wed Nov 15, 2017
Author(s): Kristin M. Kurianski, Anand U. Oza, and John W. M. Bush
We present the results of a numerical investigation of droplets walking in a harmonic potential. Particular attention is given to delineating the parameter regimes in which periodic and chaotic trajectories arise, and double quantization in energy and angular momentum emerges.
[Phys. Rev. Fluids 2, 113602] Published Tue Nov 14, 2017
Author(s): E. N. Kalaydin, N. Yu. Ganchenko, G. S. Ganchenko, N. V. Nikitin, and E. A. Demekhin
In an electrolyte solution near ion-selective surfaces in an external electric field we theoretically find a thermoelectrokinetic instability and study it numerically. The instability comes from nonuniformity of the electric current and conductivity in long channels with good thermal insulation.
[Phys. Rev. Fluids 2, 114201] Published Tue Nov 14, 2017
Author(s): Kazuhiro Inagaki, Nobumitsu Yokoi, and Fujihiro Hamba
Numerical simulations have revealed that mean flow directed to the rotation axis is generated against the turbulent diffusion only in the case of both inhomogeneous helical forcing and system rotation. The origin of the phenomenon is examined in terms of the Reynolds-stress transport equation.
[Phys. Rev. Fluids 2, 114605] Published Tue Nov 14, 2017