Latest papers in fluid mechanics
Author(s): Demosthenes Kivotides
A model of normal-fluid dynamics and its coupling with superfluid vortices is formulated. The role of axial flow instabilities of superfluid vortices in energy transfer from normal-fluid to superfluid turbulence is indicated.
[Phys. Rev. Fluids 3, 104701] Published Mon Oct 08, 2018
Author(s): P. Galatola
A liquid droplet spread on a solid substrate with nonuniform curvature, such as a conical surface, spontaneously moves. By assuming that the only source of dissipation is the contact line viscosity, we perturbatively determine the speed of the droplet and the total capillary force acting on it.
[Phys. Rev. Fluids 3, 103601] Published Fri Oct 05, 2018
Author(s): Ingrith Cuellar, Pablo D. Ravazzoli, Javier A. Diez, Alejandro G. González, Nicholas A. Roberts, Jason D. Fowlkes, Philip D. Rack, and Lou Kondic
We report experiments, modeling, and numerical simulations of the self–assembly of particle patterns obtained from a nanometric metallic square grid. Initially, nickel filaments of rectangular cross section are patterned on a SiO2 flat surface, and then they are melted by laser irradiation with ∼18-...
[Phys. Rev. E 98, 043101] Published Thu Oct 04, 2018
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): Jörg Schumacher, Ambrish Pandey, Victor Yakhot, and Katepalli R. Sreenivasan
If a fluid flow is driven by a weak Gaussian random force, the nonlinearity in the Navier-Stokes equations is negligibly small and the resulting velocity field obeys Gaussian statistics. Nonlinear effects become important as the driving becomes stronger and a transition occurs to turbulence with ano...
[Phys. Rev. E 98, 033120] Published Fri Sep 28, 2018
Author(s): Y. Ben-Ami and A. Manela
We study the response of a rarefied gas in a slab to the motion of its boundaries in the tangential direction. Different from previous investigations, we consider boundaries displacements at nonsmall Mach (Ma) numbers, coupling the dynamic and thermodynamic gas states, and deviating the system from ...
[Phys. Rev. E 98, 033121] Published Fri Sep 28, 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
Solutal convection in porous media: Comparison between boundary conditions of constant concentration and constant flux
Author(s): Mohammad Amin Amooie, Mohamad Reza Soltanian, and Joachim Moortgat
We numerically examine solutal convection in porous media, driven by the dissolution of carbon dioxide (CO2) into water—an effective mechanism for CO2 storage in saline aquifers. Dissolution is associated with slow diffusion of free-phase CO2 into the underlying aqueous phase followed by density-dri...
[Phys. Rev. E 98, 033118] Published Thu Sep 27, 2018
Author(s): J. J. J. Gillissen and H. J. Wilson
We develop a model for the microstructure and the stress, in dense suspensions of non-Brownian, perfectly smooth spheres at vanishing particle Reynolds number. These quantities are defined in terms of the second-order moment a of the distribution function of the orientation unit vector between hydro...
[Phys. Rev. E 98, 033119] Published Thu Sep 27, 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): Prateek Gupta and Carlo Scalo
We present a numerical and theoretical investigation of the nonlinear spectral energy cascade of decaying finite-amplitude planar acoustic waves in a single-component ideal gas at standard temperature and pressure. We analyze various one-dimensional canonical flow configurations: a propagating trave...
[Phys. Rev. E 98, 033117] Published Tue Sep 25, 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): Yoav Green
Permselective nanochannels can rectify the electric current transported through them similar to solid-state diodes. The rectification is due to symmetry breaking related to distribution of the nanochannels’ surface charge as well as the geometry. Thus far, most of the works related to the asymmetric...
[Phys. Rev. E 98, 033114] Published Mon Sep 24, 2018