Latest papers in fluid mechanics
Author(s): Endao Han, Matthieu Wyart, Ivo R. Peters, and Heinrich M. Jaeger
Snapshot of a propagating shear front that transforms a dense suspension from a fluid into a jammed, solid-like state. A comprehensive description of this transformation is developed, which links the transient dynamics to parameters obtainable from steady-state rheology.
[Phys. Rev. Fluids 3, 073301] Published Wed Jul 11, 2018
Resolvent analysis of separated and attached flows around an airfoil at transitional Reynolds number
Author(s): Nikitas Thomareis and George Papadakis
Cross-stream component of the optimal response at the natural shear layer frequency (solid black line: displacement thickness of the boundary layer, solid brown line: zero-streamwise mean velocity contour).
[Phys. Rev. Fluids 3, 073901] Published Wed Jul 11, 2018
Author(s): C. Frederik Brasz, Casey T. Bartlett, Peter L. L. Walls, Elena G. Flynn, Yingxian Estella Yu, and James C. Bird
High-speed imaging experiments and numerical simulations show that the minimum size of drops ejected after bubble bursting is determined by an interplay of viscous and inertial-capillary forces both prior and subsequent to jet formation. Implications for sea spray aerosol generation are discussed.
[Phys. Rev. Fluids 3, 074001] Published Wed Jul 11, 2018
Author(s): R. Jäger, M. Mendoza, and H. J. Herrmann
Using a coupled lattice Boltzmann method/discrete element method model, the clogging of a pore with particles at microscopic scale is studied. We show that erosive bursts occur when the hydraulic pressure exceeds a critical point, which depends on the adhesive forces and the pores’ geometry.
[Phys. Rev. Fluids 3, 074302] Published Wed Jul 11, 2018
Author(s): Yaomin Zhao, Shiying Xiong, Yue Yang, and Shiyi Chen
There is a continued debate about the generation mechanism of turbulent spots in boundary-layer transition. We use the vortex-surface field to show that the sinuous distortion of vortex surfaces plays an important role in the rapid lateral growth of turbulent spots.
[Phys. Rev. Fluids 3, 074701] Published Wed Jul 11, 2018
Author(s): Samriddhi Sankar Ray
Simulations of Lagrangian turbulence with Fourier components removed (decimation) show no effect on the level of chaos but an emergent time reversality as indicated by the ratio of Lyapunov exponents shown in the figure.
[Phys. Rev. Fluids 3, 072601(R)] Published Tue Jul 10, 2018
External intermittency compensation of dissipation scale distributions in a turbulent boundary layer
Author(s): Sabah F. H. Alhamdi and Sean C. C. Bailey
We investigate the effect of external intermittency on dissipation scales in turbulent boundary layer flow at Reτ≈1000 using a single hot wire probe for one point longitudinal velocity measurements. We find improved scaling universality by accounting for external intermittency throughout the flow.
[Phys. Rev. Fluids 3, 074601] Published Tue Jul 10, 2018
Physics-informed machine learning approach for augmenting turbulence models: A comprehensive framework
Author(s): Jin-Long Wu, Heng Xiao, and Eric Paterson
We present a comprehensive framework for augmenting turbulence models with physics-informed machine learning, illustrating a complete workflow from identification of input/output to prediction of mean velocities. The learned model has Galilean invariance and coordinate rotational invariance.
[Phys. Rev. Fluids 3, 074602] Published Tue Jul 10, 2018
Author(s): Hussein N. Dalgamoni and Xin Yong
Droplet-solid interaction is a ubiquitous fluid phenomenon that underpins a wide range of applications. To further the understanding of this important problem, we use an axisymmetric lattice Boltzmann method (LBM) to model the droplet impact on a solid surface with different wettability. The method ...
[Phys. Rev. E 98, 013102] Published Mon Jul 09, 2018
Electrohydrodynamic interaction, deformation, and coalescence of suspended drop pairs at varied angle of incidence
Author(s): Qingming Dong and Amalendu Sau
For a pair of suspended leaky drops, the computed drop velocity (u) with varied permittivity-ratio (εin/εout) and two ‘outflow’ outer vortex pairs drive prolate and oblate deformation mechanisms. Two drops diverge for positive ‘u’ and move closer together and coalesce for negative ‘u’.
[Phys. Rev. Fluids 3, 073701] Published Mon Jul 09, 2018
Controlling wetting with electrolytic solutions: Phase-field simulations of a droplet-conductor system
Author(s): Gaute Linga, Asger Bolet, and Joachim Mathiesen
The wetting properties of immiscible two-phase systems are crucial in applications ranging from laboratory-on-a-chip devices to field-scale oil recovery. It has long been known that effective wetting properties can be altered by the application of an electric field; a phenomenon coined as electrowet...
[Phys. Rev. E 98, 013101] Published Thu Jul 05, 2018
Author(s): Petter Johansson and Berk Hess
Molecular processes of contact line advancement in dynamic wetting is investigated for no-slip systems using computer simulations. The energy dissipation at the contact line is measured and shown to be large for mesoscopic systems. A model for the dissipation term is proposed.
[Phys. Rev. Fluids 3, 074201] Published Thu Jul 05, 2018
Author(s): Di Li and Xiangchun Xuan
Particles migrate towards the center or walls of a rectangular microchannel if they lead or lag a viscoelastic fluid flow due to positive and negative electrophoresis, respectively. This is opposite to a Newtonian fluid. We attribute this to the shear-induced extra lift in a viscoelastic fluid.
[Phys. Rev. Fluids 3, 074202] Published Thu Jul 05, 2018
Author(s): M. Lebon, J. Sebilleau, and C. Colin
Experiments on air bubbles nucleated on an inclined plate show the importance of the bubble foot shape. A new expression for the capillary force is proposed to predict the bubble detachment diameter.
[Phys. Rev. Fluids 3, 073602] Published Tue Jul 03, 2018
Author(s): R. C. Hidalgo, B. Szabó, K. Gillemot, T. Börzsönyi, and T. Weinhart
Our discrete element simulations and laboratory experiments revealed that density and friction are well-defined functions of the effective inertial number, which fully captures the effect of grain elongation.
[Phys. Rev. Fluids 3, 074301] Published Tue Jul 03, 2018
Author(s): Hannah M. Kittel, Ilia V. Roisman, and Cameron Tropea
Experiments on single drop impacts on thin films of another liquid are analyzed theoretically over 8 orders of magnitude in viscosity ratio νf/νd. Away from νf≊νd we find that the K-numbers determine the splashing threshold and in that region a modified K-number, which we introduce, is needed.
[Phys. Rev. Fluids 3, 073601] Published Mon Jul 02, 2018
Author(s): Christopher Nilsen
We study the thermoviscous fingering instability problem that develops when an injected fluid is displacing a fluid with different temperature and viscosity in a Hele-Shaw cell or porous medium. Using linear stability theory, we show how the thermal front caused by the different temperature of the i...
[Phys. Rev. E 97, 063112] Published Fri Jun 29, 2018
Author(s): Masoud Mohammadi-Arzanagh, Saeed Mahdisoltani, Rudolf Podgornik, and Ali Naji
Driving a planar thin film of a compressible viscous fluid using random surface forcing leads to remarkable fluctuation-induced stresses on the bounding surfaces of the film, exhibiting power-law, or even non-decaying, behaviors as a function of the film thickness.
[Phys. Rev. Fluids 3, 064201] Published Fri Jun 29, 2018
Author(s): Hsiang-Ying Chen, Chun-Yu Liu, and Lin I
Experiments find that rogue wave events for Faraday waves tend to be preceded one period before by a surrounding waveform of high angular average and small variation of wave height.
[Phys. Rev. Fluids 3, 064401] Published Thu Jun 28, 2018
Preferential concentration of noninertial buoyant particles in the ocean mixed layer under free convection
Author(s): Tomás Chor, Di Yang, Charles Meneveau, and Marcelo Chamecki
A large eddy simulation is used to study the surface patterns of noninertial passive buoyant particles in the ocean mixed layer. A mechanism for preferential concentration that is independent of inertial effects is then identified and quantified as a function of the terminal rise velocity.
[Phys. Rev. Fluids 3, 064501] Published Thu Jun 28, 2018