Physical Review Fluids

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Recent articles in Physical Review Fluids
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Role of medium heterogeneity and viscosity contrast in miscible flow regimes and mixing zone growth: A computational pore-scale approach

Tue, 05/08/2018 - 11:00

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

Absolute/convective secondary instabilities and the role of confinement in free shear layers

Mon, 05/07/2018 - 11:00

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

Study of subgrid-scale velocity models for reacting and nonreacting flows

Fri, 05/04/2018 - 11:00

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

Inviscid criterion for decomposing scales

Fri, 05/04/2018 - 11:00

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

Characteristics of sources and sinks of momentum in a turbulent boundary layer

Thu, 05/03/2018 - 11:00

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

Boiling regimes of impacting drops on a heated substrate under reduced pressure

Wed, 05/02/2018 - 11:00

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

Flow produced by a free-moving floating magnet driven electromagnetically

Mon, 04/30/2018 - 11:00

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

Fluid flow in a porous medium with transverse permeability discontinuity

Mon, 04/30/2018 - 11:00

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

Mon, 04/30/2018 - 11:00

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

Mon, 04/30/2018 - 11:00

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