Physical Review Fluids
Author(s): Rémy Herbaut, Philippe Brunet, Laurent Limat, and Laurent Royon
Spreading of liquid on a cold substrate with freezing is investigated. Experimental investigation of the criterion for a solidification-induced pinning of the liquid near the triple line finds that below a temperature-dependent velocity, spreading shows stick-slip dynamics.
[Phys. Rev. Fluids 4, 033603] Published Wed Mar 27, 2019
Author(s): Xingjun Fang, Bing-Chen Wang, and Donald J. Bergstrom
A generalized framework of incorporating vortex identifiers into subgrid-scale models for large-eddy simulation is presented. The proposed models can automatically identify the under-resolved vortex stretching process and drain energy from the inertial subrange.
[Phys. Rev. Fluids 4, 034606] Published Tue Mar 26, 2019
Author(s): Semyon Churilov and Yury Stepanyants
Wave scattering on a bathtub vortex in shallow water is studied in the linear approximation. The results obtained are relevant to the interpretation of laboratory experiments and can be considered the hydrodynamic model of wave scattering by a rotating black hole in general relativity.
[Phys. Rev. Fluids 4, 034704] Published Tue Mar 26, 2019
Author(s): John LaGrone, Ricardo Cortez, and Lisa Fauci
We examine the swimming of an elastic helix rotated by a torque at its base, both in free-space and confined to a tube. The image depicts the envelope of an excursion of a filament centerline over one rotation; the blue is the surface of the finite-radius helical filament at one snapshot in time.
[Phys. Rev. Fluids 4, 033102] Published Mon Mar 25, 2019
Author(s): Rémi Menaut, Yoann Corre, Ludovic Huguet, Thomas Le Reun, Thierry Alboussière, Michael Bergman, Renaud Deguen, Stéphane Labrosse, and Marc Moulin
Compressible thermal convection is experimentally studied. In the large apparent gravity of a rotor centrifuge, using xenon gas, an adiabatic temperature difference of 14 °C over a height equal to 4 cm is obtained. Large Coriolis forces impose a quasigeostrophic regime.
[Phys. Rev. Fluids 4, 033502] Published Mon Mar 25, 2019
Author(s): Thomas E. Videbæk and Sidney R. Nagel
Diffusion between miscible fluids in the viscous-fingering instability produces an unexpected transition into a novel pattern. Usually thought of as a two-dimensional phenomena, this works shows the importance of three-dimensional structure to the patterns that form.
[Phys. Rev. Fluids 4, 033902] Published Mon Mar 25, 2019
Author(s): F. Charru and P. Luchini
Potential flow analysis is used to find the elevation profile of traveling dunes of given volume and locate the brink point where the flow separates without singularity.
[Phys. Rev. Fluids 4, 034304] Published Mon Mar 25, 2019
Author(s): A. Rubbert, M. Albers, and W. Schröder
Streamline segment statistics are collected from tomographic particle image velocimetry and direct numerical simulation data of a turbulent wavy channel flow. The model equation for such statistics is adapted for inhomogeneous turbulence. The novel formulation is applied to explain the observations and identify the locally acting mechanisms.
[Phys. Rev. Fluids 4, 034605] Published Mon Mar 25, 2019
Author(s): Jason R. Picardo, Lokahith Agasthya, Rama Govindarajan, and Samriddhi Sankar Ray
Direct numerical simulations find that rapid head-on collisions of particles mostly occur in regions of straining compared to vortical regions, and that intense vortex tubes conspire with enveloping straining sheets, in the form of vortex-strain worm-rolls, to generate violent collisions.
[Phys. Rev. Fluids 4, 032601(R)] Published Thu Mar 21, 2019
Author(s): Jacob Hale and Jacob Boudreau
A meniscus formed around a vertical cylinder looks and behaves like a repulsive central potential, deflecting noncoalescent droplets analogous to Rutherford scattering. The scattering behavior is used to probe the potential of the cylindrical meniscus, confirming theoretical models for its shape.
[Phys. Rev. Fluids 4, 033602] Published Thu Mar 21, 2019
Modal analysis with proper orthogonal decomposition of hypersonic separated flows over a double wedge
Author(s): Ozgur Tumuklu, Deborah A. Levin, and Vassilis Theofilis
A study combining direct simulation Monte Carlo simulations with window proper orthogonal decomposition investigates the temporal characteristics of unsteady, laminar shock boundary-layer interactions for different gas mixtures for an Edney type-IV flow.
[Phys. Rev. Fluids 4, 033403] Published Tue Mar 19, 2019
Author(s): Truong Pham and Satish Kumar
Colloidal particles inside an evaporated droplet on a solid substrate are often preferentially deposited at the droplet contact line, a phenomenon known as the coffee-ring effect. A study shows how this phenomenon is affected by the permeability of the substrate.
[Phys. Rev. Fluids 4, 034004] Published Tue Mar 19, 2019
Author(s): Ruiying Li, Jacques Borée, Bernd R. Noack, Laurent Cordier, and Fabien Harambat
We propose a windward bi-frequency control strategy to manipulate experimentally the wake past a yawed car model using pulsed jets. By varying the low frequency value in the actuation, we can provide a complete authority for the manipulation of the mean wake orientation and reduce drag.
[Phys. Rev. Fluids 4, 034604] Published Tue Mar 19, 2019
Author(s): Matthew Butler, Finn Box, Thomas Robert, and Dominic Vella
Inspired by the droplet-mediated adhesion of insects, the adhesion between soft and rigid surfaces mediated by a droplet is studied. Deformability allows for enhanced adhesion as well as new routes for “unsticking,” but the dynamics of adhesion also plays a role.
[Phys. Rev. Fluids 4, 033601] Published Mon Mar 18, 2019
Author(s): C. M. Boyce, A. Penn, A. Padash, M. Lehnert, K. P. Pruessmann, and C. R. Müller
Rapid magnetic resonance imaging shows how bubbles collapse in fluidized beds as a result of gas channeling to neighboring bubbles.
[Phys. Rev. Fluids 4, 034303] Published Mon Mar 18, 2019
Importance of small-scale anisotropy in the turbulent/nonturbulent interface region of turbulent free shear flows
Author(s): O. R. H. Buxton, M. Breda, and K. Dhall
Turbulent flows are often bounded by nonturbulent fluid with a sharp interface between the two flow states. Drawing a parallel between this interface and the wall in a wall-bounded flow and similarly, to wall-bounded turbulence, shows the importance of the anisotropy very close to the interface.
[Phys. Rev. Fluids 4, 034603] Published Mon Mar 18, 2019
Author(s): X. I. A. Yang, S. Zafar, J.-X. Wang, and H. Xiao
A study shows that when trained using channel flow data at just one Reynolds number and informed with known flow physics, the neural network works robustly as a wall model in large-eddy simulation (LES) of channel flow at any Reynolds number. It also outperforms the equilibrium wall model in LES of a 3D boundary layer flow.
[Phys. Rev. Fluids 4, 034602] Published Fri Mar 15, 2019
Orientation dependent elastic stress concentration at tips of slender objects translating in viscoelastic fluids
Author(s): Chuanbin Li, Becca Thomases, and Robert D. Guy
The elastic stress generated moving in a purely viscous flow around a slender cylinder is found to be large near the tips, and larger when the flow is parallel to the axis.
[Phys. Rev. Fluids 4, 031301(R)] Published Thu Mar 14, 2019
Author(s): Y. Ben-Ami and A. Manela
The effect of heat-flux conditions on the Rayleigh-Bénard convection in a rarefied gas is investigated, extending instability to higher rarefaction rates compared with the isothermal walls case. The deviation from the Boussinesq limit with increasing compressibility is analyzed.
[Phys. Rev. Fluids 4, 033402] Published Thu Mar 14, 2019
Author(s): Allison Lee and Julie Crockett
Evanescent regions exist in numerous areas of the deep ocean where the stratification also varies with depth. Using theoretical predictions and experiments, the kinetic energy density in propagating internal waves generated from these evanescent regions is explored.
[Phys. Rev. Fluids 4, 034803] Published Thu Mar 14, 2019