Physical Review Fluids
Author(s): Nimish Pujara, Theresa B. Oehmke, Ankur D. Bordoloi, and Evan A. Variano
Rotations of large, neutrally buoyant, anisotropic particles in isotropic turbulence are studied. The rotation rate probability density function and its moments are found to be simple functions of particle shape and size. These are compared with structure functions in the flow to understand the effects of finite particle size.
[Phys. Rev. Fluids 3, 054605] Published Wed May 16, 2018
Author(s): Anaïs Gauthier, Ambre Bouillant, Christophe Clanet, and David Quéré
Impacting drops can be reflected by moving solid plates, provided the surface moves fast enough. The threshold speed of bouncing is described and modeled, along with the dynamics of liquid removal. Viscous or low surface tension liquids, usually impossible to repel, are thus efficiently swept away.
[Phys. Rev. Fluids 3, 054002] Published Tue May 15, 2018
Author(s): Guillaume Michel, Benoît Semin, Annette Cazaubiel, Florence Haudin, Thomas Humbert, Simon Lepot, Félicien Bonnefoy, Michaël Berhanu, and Éric Falcon
Experiments are performed in a large basin to investigate nonlinear gravity waves generated by a periodic or a slowly modulated forcing. High-frequency self-similar spectra ascribed to bound waves are reported, which share similarities with the ones observed in previous experiments of wave turbulence.
[Phys. Rev. Fluids 3, 054801] Published Tue May 15, 2018
Dynamic heterogeneity and conditional statistics of non-Gaussian temperature fluctuations in turbulent thermal convection
Author(s): Xiaozhou He, Yin Wang, and Penger Tong
We present a theoretical model with no free parameters to describe a class of turbulent fluctuations with an exponential tail in the probability density function. For turbulent thermal convection the model (solid line) is compared with measured temperature distributions (symbols), and agrees well.
[Phys. Rev. Fluids 3, 052401(R)] Published Mon May 14, 2018
Author(s): Xinan Liu, An Wang, Shuang Wang, and Dejun Dai
The cavity and central jet produced by the impact of a water drop on a water surface in a wind field are experimentally studied. Results show that the dynamics of the central jet are controlled by two mechanisms: the oblique impact caused by the wind and the wind drag directly acting on the jet.
[Phys. Rev. Fluids 3, 053602] Published Mon May 14, 2018
Author(s): A. Frezzotti, L. Gibelli, D. A. Lockerby, and J. E. Sprittles
Evaporation of a binary liquid into vacuum is studied through a mean-field kinetic theory approach. It is found that evaporated atoms are distributed according to anisotropic Maxwellians, and evaporation coefficients are only mildly dependent on the liquid-vapor interface composition and temperature.
[Phys. Rev. Fluids 3, 054001] Published Mon May 14, 2018
Author(s): E. Calzavarini, Y. X. Huang, F. G. Schmitt, and L. P. Wang
The statistical properties of the measurements performed by tiny self-propelled probes drifting in a turbulent flow are studied by means of a numerical model system. Their nontrivial combination of Lagrangian and Eulerian features are highlighted both in fluid velocity and scalar field time-series.
[Phys. Rev. Fluids 3, 054604] Published Fri May 11, 2018
Role of medium heterogeneity and viscosity contrast in miscible flow regimes and mixing zone growth: A computational pore-scale approach
Author(s): Saied Afshari, S. Hossein Hejazi, and Apostolos Kantzas
The mixing length growth in the miscible displacement through granular porous media is evaluated. Scaling laws are proposed to quantify the role of medium heterogeneity, viscosity contrast, and injection rate on the solution mixing.
[Phys. Rev. Fluids 3, 054501] Published Tue May 08, 2018
Author(s): Cristóbal Arratia, Saviz Mowlavi, and François Gallaire
Mixing layers can grow in time or space by vortex pairings that succeed each other in a nearly self-similar way. We use a point vortex model to study how confinement eventually limits this growth process, leading us to propose a wavelength selection mechanism for free shear layers with counterflow.
[Phys. Rev. Fluids 3, 053901] Published Mon May 07, 2018
Author(s): I. Langella, N. A. K. Doan, N. Swaminathan, and S. B. Pope
The accuracy of subgrid scale velocity kinetic energy models for reacting and nonreacting flows is studied using direct numerical simulation data. The analysis shows the dissipation of momentum, not taken into account in existing models, to be the key factor. A new model, localized diffusion-dissipation, is proposed on the basis of this result.
[Phys. Rev. Fluids 3, 054602] Published Fri May 04, 2018
Author(s): Dongxiao Zhao and Hussein Aluie
Length scale in a flow depends on the decryption key used to decipher length scales and the communications between them. Analysis shows that some of the decryption keys widely used can, in fact, obfuscate the physics, whereas one of them allows us to unravel the correct multiscale dynamics.
[Phys. Rev. Fluids 3, 054603] Published Fri May 04, 2018
Author(s): D. Fiscaletti and B. Ganapathisubramani
In turbulent boundary layers, the wall-normal gradient of the Reynolds shear stress identifies momentum sources and sinks. The spacetime evolution of these small-scale motions is experimentally investigated in a turbulent boundary layer with time-resolved particle image velocimetry.
[Phys. Rev. Fluids 3, 054601] Published Thu May 03, 2018
Author(s): Michiel A. J. van Limbeek, Paul B. J. Hoefnagels, Minori Shirota, Chao Sun, and Detlef Lohse
Reduction of the ambient pressure changes the boiling behavior of impacting ethanol drops on a heated substrate as observed by contact area measurements (insets). With decreasing ambient pressure, we find a widening of the transition boiling regime, while TLeidenfrost stays roughly constant.
[Phys. Rev. Fluids 3, 053601] Published Wed May 02, 2018
Author(s): Saúl Piedra, Joel Román, Aldo Figueroa, and Sergio Cuevas
In an experimental and numerical study, a magnet floating in a thin electrolyte layer is dragged and accelerated by a vortex dipole generated by a Lorentz force. Vortex shedding appears when a sufficiently high electric current is applied, promoting a zigzag magnet motion.
[Phys. Rev. Fluids 3, 043702] Published Mon Apr 30, 2018
Author(s): Galina E. Pavlovskaya, Thomas Meersmann, Chunyu Jin, and Sean P. Rigby
Magnetic resonance imaging is used to map out velocity fields during fluid flow in a clear channel coupled to a permeable wall. The maps are compared to lattice Boltzmann modeling to demonstrate that the velocity fields can be simulated without analytical expression of the boundary velocities.
[Phys. Rev. Fluids 3, 044102] Published Mon Apr 30, 2018
Hybrid finite-difference/lattice Boltzmann simulations of microchannel and nanochannel acoustic streaming driven by surface acoustic waves
Author(s): Ming K. Tan and Leslie Y. Yeo
The acoustic streaming flow in microchannels and nanochannels caused by complex fluid-structural coupling due to surface acoustic waves is studied using a hybrid continuum and mesoscale numerical model.
[Phys. Rev. Fluids 3, 044202] Published Mon Apr 30, 2018
Propulsion and maneuvering of an artificial microswimmer by two closely spaced waving elastic filaments
Author(s): Roei Elfasi, Yossef Elimelech, and Amir D. Gat
Hydrodynamic interaction between two adjacent waving elastic filaments is examined analytically and experimentally. Results show that antiphase beating is optimal for propulsion, hydrodynamic interaction modifies the optimal Sperm number, and phase difference between the filaments enables maneuvering.
[Phys. Rev. Fluids 3, 044203] Published Mon Apr 30, 2018
Author(s): Alexander Yelkhovsky and W. Val Pinczewski
Fluid inertia is usually ignored in network models used to predict flow in porous media. A model based on an averaged Navier-Stokes equation, validated for displacements in straight capillaries, is shown to capture the effects of inertia. Results suggest it can form the basis for more realistic network models.
[Phys. Rev. Fluids 3, 044003] Published Fri Apr 27, 2018
Author(s): Megan S. Davies Wykes, Jinzi Mac Huang, George A. Hajjar, and Leif Ristroph
Using candy “landforms” carved and reshaped by flowing water, laboratory experiments show how it is that some shapes keep a memory of earlier conditions as they develop while others forget the past, a fact that is important in geological dating and understanding how landscapes form.
[Phys. Rev. Fluids 3, 043801] Published Thu Apr 26, 2018
Author(s): Babak Nasouri and Gwynn J. Elfring
The effects of higher-order force moments of active particles on the flow field induced by their motion are investigated. Using the reciprocal theorem, explicit expressions for the stresslet dipole, rotlet dipole, and potential dipole of an arbitrarily shaped active particle are provided.
[Phys. Rev. Fluids 3, 044101] Published Wed Apr 25, 2018