Physical Review Fluids
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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