New Papers in Fluid Mechanics

Author(s): Gualtiero Badin and Anna M. Barry

Point-vortex models are presented for the generalized Euler equations, which are characterized by a fractional Laplacian relation between the active scalar and the stream function. Special focus is given to the case of the surface quasigeostrophic (SQG) equations, for which the existence of finite-t...

[Phys. Rev. E 98, 023110] Published Wed Aug 29, 2018

Author(s): Jiajia Zhou and Masao Doi

Exponential thinning of a viscoelastic filament is analyzed using the Onsager variational principle.

[Phys. Rev. Fluids 3, 084004] Published Wed Aug 29, 2018

Author(s): Maxime Bassenne, Parviz Moin, and Javier Urzay

The preferential concentration of inertial particles in isotropic turbulence is studied using wavelets, enabling the joint scale-space analysis of the flow field of the carrier phase, the concentration field of the dispersed phase, and interphase conditioned statistics.

[Phys. Rev. Fluids 3, 084304] Published Wed Aug 29, 2018

Author(s): Yayun Wang and Andrea Prosperetti

Resolved simulations of turbulent flow past a fixed planar array of cold particles show the fundamental differences between velocity and temperature fields, cast light on the limitations of the point particle model and illustrate the mechanism by which turbulence disrupts the thermal wakes.

[Phys. Rev. Fluids 3, 084305] Published Wed Aug 29, 2018

Author(s): Kyupaeck Jeff Rah, Chandru Dhandapani, and Guillaume Blanquart

Turbulence forcing techniques are often required in the numerical simulation of turbulent flows. A novel forcing technique, based on physics, is devised to reproduce the centerline turbulent characteristics of round jets in a triply periodic box.

[Phys. Rev. Fluids 3, 084606] Published Wed Aug 29, 2018

Author(s): JiaCheng Hu and Sean D. Peterson

An investigation of the interaction of a vortex ring colliding with a coaxially aligned aperture, which extends the classical problem of a vortex ring impacting a solid wall, examines the behaviors of near-wall vortices in the proximity of a structural discontinuity (aperture tip).

[Phys. Rev. Fluids 3, 084701] Published Wed Aug 29, 2018

Author(s): Dan Soto, Henri-Louis Girard, Antoine Le Helloco, Thomas Binder, David Quéré, and Kripa K. Varanasi

Factors governing atomization of droplets impacting a mesh, starting with the elementary unit of a single hole, are investigated. It is shown how this process can be used to generate finely controlled sprays with micrometric droplet sizes and low kinetic energy, as is critical for agricultural applications.

[Phys. Rev. Fluids 3, 083602] Published Tue Aug 28, 2018

Author(s): Hannu Teisala, Clarissa Schönecker, Anke Kaltbeitzel, Werner Steffen, Hans-Jürgen Butt, and Doris Vollmer

Wetting over liquid films governs important phenomena but is poorly understood. A water front moving over a micrometer-thick film of silicone oil on a solid surface is imaged. Capillary suction in the meniscus induces thinning of the oil film and a wavelike film profile with local backflows.

[Phys. Rev. Fluids 3, 084002] Published Tue Aug 28, 2018

Author(s): Takeru Morita, Toshihiro Omori, and Takuji Ishikawa

The artificial microswimmer is a cutting-edge technology with applications in drug delivery and micro-total-analysis systems. The flow field around a microswimmer can be regarded as Stokes flow, in which reciprocal body deformation cannot induce migration. In this study, we propose a microcapsule sw...

[Phys. Rev. E 98, 023108] Published Mon Aug 27, 2018

Author(s): Christophe Henry, Giorgio Krstulovic, and Jérémie Bec

This paper investigates the effect of inertia on the dynamics of elongated chains to go beyond the overdamped case that is often used to study such systems. For that purpose, numerical simulations are performed considering the motion of freely jointed bead-rod chains in an extensional flow in the pr...

[Phys. Rev. E 98, 023107] Published Fri Aug 24, 2018

Author(s): H. M. De La Rosa Zambrano, G. Verhille, and P. Le Gal

Aggregation and fragmentation are frequently observed in industrial and natural systems. In an experimental study, an initially large aggregate of magnetic particles is broken by the turbulent fluctuations of a flow. The size of the resulting clusters is measured using three-dimensional reconstruction.

[Phys. Rev. Fluids 3, 084605] Published Fri Aug 24, 2018

Author(s): J. Muñoz, J. Arcos, O. Bautista, and F. Méndez

The dispersion coefficient of a passive solute into a pulsatile electroosmotic flow with slippage at the microcapillary wall is derived. We found that the slip condition can enhance the dispersion coefficient by up to two orders of magnitude over the no-slip condition.

[Phys. Rev. Fluids 3, 084503] Published Thu Aug 23, 2018

Author(s): Hidenori Tanaka, Alpha A. Lee, and Michael P. Brenner

[Phys. Rev. Fluids 3, 089901] Published Thu Aug 23, 2018

Author(s): Pedro S. Volpiani, Matteo Bernardini, and Johan Larsson

The effects of wall thermal conditions on the canonical case of an impinging shock wave interacting with a turbulent boundary layer is an under-explored topic. Direct numerical simulations are used to study the flow properties of supersonic shock/boundary-layer interactions with distinct wall thermal conditions and shock angles.

[Phys. Rev. Fluids 3, 083401] Published Wed Aug 22, 2018

Author(s): Evan H. Anders, Benjamin P. Brown, and Jeffrey S. Oishi

A mechanism for rapidly achieving thermal relaxation in high-Pe convective simulations is studied in the context of Rayleigh-Bénard convection. It achieves statistically similar states to standard timestepping and saves up to an order of magnitude in computational time for the problems studied.

[Phys. Rev. Fluids 3, 083502] Published Tue Aug 21, 2018

Author(s): Seong Jin Kim, Seungho Kim, and Sunghwan Jung

When a dog accelerates its tongue to lap water, a water column is created and pinches off close to the tongue. Physical experiments and a theoretical model of accelerating a solid sphere from a liquid bath elucidate the mechanism of the liquid-column formation and pinch-off.

[Phys. Rev. Fluids 3, 084001] Published Tue Aug 21, 2018

Author(s): S. Başbuğ, G. Papadakis, and J. C. Vassilicos

Fractal impellers can lead to a considerably shorter mixing time compared to regular impellers. This is explained by the differences in characteristics of flow and scalar fields. Moreover, a mathematical model is proposed which can approximate the decay rate of the passive scalar fluctuations.

[Phys. Rev. Fluids 3, 084502] Published Tue Aug 21, 2018

Author(s): Nisat Nowroz Anika, Lyazid Djenidi, and Sedat Tardu

Implementation of a bypass laminar-to-turbulent transition is explored. We show that our method, by bypassing linear exponential growth, can induce high mixing capacity localized turbulence in a laminar channel flow at low Re. An on-demand mixing enhancement in laminar channel flow is proposed.

[Phys. Rev. Fluids 3, 084604] Published Tue Aug 21, 2018

Author(s): Rodica Borcia, Michael Bestehorn, Sebastian Uhlig, Matthieu Gaudet, and Harald Schenk

An original mathematical tool suitable for describing fluid dynamics in micropumps induced by transverse forced vibrations of an elastic beam is presented. The model could also be used in designing engineering software for micromachinery applications.

[Phys. Rev. Fluids 3, 084202] Published Mon Aug 20, 2018