Physical Review Fluids

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Inertial forces for particle manipulation near oscillating interfaces

Thu, 10/04/2018 - 11:00

Author(s): Siddhansh Agarwal, Bhargav Rallabandi, and Sascha Hilgenfeldt

Oscillating microscale interfaces give rise not only to steady flows, but also steady inertial forces on particles. Our efficient theoretical description of these forces, which can be attractive or repulsive, provides a toolbox for separating and sorting microscale objects like biological cells.


[Phys. Rev. Fluids 3, 104201] Published Thu Oct 04, 2018

Large-scale structure of velocity and passive scalar fields in freely decaying homogeneous anisotropic turbulence

Thu, 10/04/2018 - 11:00

Author(s): Katsunori Yoshimatsu and Yukio Kaneda

It is shown that there are an infinite number of invariants characterizing the large-scale structure in certain kinds of freely-decaying homogeneous turbulent velocity and passive scalar fields. A self-similarity assumption suggests that the large-scale anisotropy of the fields is persistent.


[Phys. Rev. Fluids 3, 104601] Published Thu Oct 04, 2018

Numerical investigation of breaking internal solitary waves

Thu, 10/04/2018 - 11:00

Author(s): Giovanni la Forgia, Talia Tokyay, Claudia Adduce, and George Constantinescu

With high-resolution 3D large Eddy Simulations we study internal solitary waves differently breaking over a sloping boundary. The entrainment parameter and mixing efficiency pry apart two effects of turbulent instabilities occurring in stratified fluid in terms of changes in bulk density profile.


[Phys. Rev. Fluids 3, 104801] Published Thu Oct 04, 2018

Generalization of Taylor's formula to particles of arbitrary inertia

Tue, 10/02/2018 - 11:00

Author(s): S. Boi, A. Mazzino, P. Muratore-Ginanneschi, and S. Olivieri

In the early 1920s Sir G. I. Taylor derived a formula that can be fairly considered one of the cornerstones of large-scale tracer transport. Here, we extend Taylor’s formula to particles of any inertia including Basset and Faxèn corrections, plus other forces in the particle dynamics.


[Phys. Rev. Fluids 3, 104501] Published Tue Oct 02, 2018

Growth of clogs in parallel microchannels

Mon, 10/01/2018 - 11:00

Author(s): Alban Sauret, Katarzyna Somszor, Emmanuel Villermaux, and Emilie Dressaire

When suspensions flow in microchannels or porous media, particles can get trapped and form clogs. A new model predicts the clogging dynamics and flow rate in simple porous media. The results are relevant to describe the aging of water filters and the influence of proppants on flow through rocks.


[Phys. Rev. Fluids 3, 104301] Published Mon Oct 01, 2018

Reynolds number effects in pipe flow turbulence of generalized Newtonian fluids

Fri, 09/28/2018 - 11:00

Author(s): J. Singh, M. Rudman, and H. M. Blackburn

Direct numerical simulations of turbulent pipe flow of power-law fluids show that the effect of shear thinning on turbulence statistics in the inner-wall region does not disappear as Re is increased. A log-law mean viscosity profile is also predicted that is self-similar in the inner region.


[Phys. Rev. Fluids 3, 094607] Published Fri Sep 28, 2018

Multiscaling analysis of the mean thermal energy balance equation in fully developed turbulent channel flow

Fri, 09/28/2018 - 11:00

Author(s): Tie Wei

Properly accounting for the intricate Prandtl number dependence in different layers of turbulent channel flows, a multiscaling analysis is developed for the mean thermal energy balance (MHB) equations. A formal analogy is established between the MHB equation and the mean momentum balance equation.


[Phys. Rev. Fluids 3, 094608] Published Fri Sep 28, 2018

Dynamics of a simple model microswimmer in an anisotropic fluid: Implications for alignment behavior and active transport in a nematic liquid crystal

Thu, 09/27/2018 - 11:00

Author(s): Abdallah Daddi-Moussa-Ider and Andreas M. Menzel

Simple model microswimmers in an oriented uniaxially anisotropic fluid, such as a nematic liquid crystal, can show rich alignment behavior due to purely hydrodynamic effects. The type of propulsion mechanism and the relative magnitudes of the different involved viscosities play a crucial role.


[Phys. Rev. Fluids 3, 094102] Published Thu Sep 27, 2018

Mean kinetic energy replenishment mechanisms in vertical-axis wind turbine farms

Wed, 09/26/2018 - 11:00

Author(s): Seyed Hossein Hezaveh and Elie Bou-Zeid

We study mean kinetic energy replenishment in a clustered farm of vertical axis wind turbines using an actuator line model in a large eddy simulation. We find that clustered designs are benefical for improving overall performance but suggest that irregular designs may have even more promise.


[Phys. Rev. Fluids 3, 094606] Published Wed Sep 26, 2018

Formation number of confined vortex rings

Wed, 09/26/2018 - 11:00

Author(s): I. Danaila, F. Luddens, F. Kaplanski, A. Papoutsakis, and S. S. Sazhin

The formation number of confined vortex rings is studied using direct numerical simulations. The structure of the vortex ring at pinch-off depends on the injection program and the confinement ratio. The value of the formation time is predicted using a model for the viscous confined vortex ring.


[Phys. Rev. Fluids 3, 094701] Published Wed Sep 26, 2018

Diffuse interface model to simulate the rise of a fluid droplet across a cloud of particles

Tue, 09/25/2018 - 11:00

Author(s): Gregory Lecrivain, Yuki Kotani, Ryoichi Yamamoto, Uwe Hampel, and Takashi Taniguchi

We simulate a fluid droplet with suspended particles rising in another fluid with a diffuse interface model in which phase boundaries are replaced with smooth spreading interfaces. We find that at low Reynolds number the droplet terminal velocity decreases exponentially with particle concentration.


[Phys. Rev. Fluids 3, 094002] Published Tue Sep 25, 2018

Direct numerical simulation of particle sedimentation in a Bingham fluid

Mon, 09/24/2018 - 11:00

Author(s): A. R. Koblitz, S. Lovett, and N. Nikiforakis

Two-dimensional numerical simulations of a suspension of sedimenting particles in a Bingham fluid find three possible regimes: all, a fraction, and none of the particles sedimenting.


[Phys. Rev. Fluids 3, 093302] Published Mon Sep 24, 2018

Viscous fingering of a draining suspension

Mon, 09/24/2018 - 11:00

Author(s): Yun Chen, Frank Malambri, and Sungyon Lee

Viscous fingering arises as air invades a draining viscous suspension. Experiments show that suspended particles delay the onset of fingering but also accelerate its growth rate. In addition, particles of select sizes are observed to coat the channel surfaces and not drain.


[Phys. Rev. Fluids 3, 094001] Published Mon Sep 24, 2018

Confinement effects on gravity-capillary wave turbulence

Mon, 09/24/2018 - 11:00

Author(s): Roumaissa Hassaini and Nicolas Mordant

The effect of confinement in a high-aspect-ratio channel on the statistical properties of weak turbulence of gravity-capillary waves at the surface of water is investigated. Discreteness due to confinement coexists with an almost one-dimensional kinetic sort of wave turbulence.


[Phys. Rev. Fluids 3, 094805] Published Mon Sep 24, 2018

Membrane filtration with complex branching pore morphology

Fri, 09/21/2018 - 11:00

Author(s): Pejman Sanaei and Linda J. Cummings

An idealized first-principles model describing filtration of a feed solution containing small particles in a microstructured porous membrane is presented. Optimal configurations for the pore microstructure are identified in terms of maximizing throughput of filtered fluid and filter lifetime.


[Phys. Rev. Fluids 3, 094305] Published Fri Sep 21, 2018

Inertioelastic Poiseuille flow over a wavy surface

Fri, 09/21/2018 - 11:00

Author(s): Simon J. Haward, Jacob Page, Tamer A. Zaki, and Amy Q. Shen

Experimental evidence is presented for the existence of critical layers in inertioelastic shear flows over wavy surfaces, where theory predicts amplification of the spanwise vorticity.


[Phys. Rev. Fluids 3, 091302(R)] Published Fri Sep 21, 2018

Scaling laws of top jet drop size and speed from bubble bursting including gravity and inviscid limit

Thu, 09/20/2018 - 11:00

Author(s): Alfonso M. Gañán-Calvo

Scaling laws are proposed for the size and the velocity of the droplet which is ejected when a bubble rises to a free surface and bursts. These new scalings consistently incorporate the effect of gravity and the limit of negligible viscosity of the liquid.


[Phys. Rev. Fluids 3, 091601(R)] Published Thu Sep 20, 2018

Onset of three-dimensionality in supersonic flow over a slender double wedge

Wed, 09/19/2018 - 11:00

Author(s): Sidharth GS, Anubhav Dwivedi, Graham V. Candler, and Joseph W. Nichols

An investigation shows that laminar supersonic flow on a 2D compression corner can destabilize to become 3D beyond a critical turn angle. This compressible instability resides in the recirculating flow, producing spiral wall flow patterns postseparation and wall temperature streaks downstream.


[Phys. Rev. Fluids 3, 093901] Published Wed Sep 19, 2018

Turbulent/nonturbulent interfaces in high-resolution direct numerical simulation of temporally evolving compressible turbulent boundary layers

Tue, 09/18/2018 - 11:00

Author(s): Xinxian Zhang, Tomoaki Watanabe, and Koji Nagata

Turbulent-nonturbulent interfaces are studied in temporally evolving subsonic and supersonic turbulent boundary layers by comparing the results of direct numerical simulations with the entrainment model based on a single vortex and the theory for spatially evolving boundary layers.


[Phys. Rev. Fluids 3, 094605] Published Tue Sep 18, 2018

Wake behind a concave curved cylinder

Tue, 09/18/2018 - 11:00

Author(s): Fengjian Jiang, Bjørnar Pettersen, Helge I. Andersson, Jongmin Kim, and Sungtae Kim

The wake behind a concave, curved cylinder configuration is investigated at different Reynolds numbers. Distinctly different wake flow regimes were observed in the computed flow field, including oblique vortex shedding and dislocations. The crucial influence of a straight vertical extension is explored.


[Phys. Rev. Fluids 3, 094804] Published Tue Sep 18, 2018

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