Physical Review Fluids

Subscribe to Physical Review Fluids feed
Recent articles in Physical Review Fluids
Updated: 1 day 23 hours ago

Simulation and stability analysis of oblique shock-wave/boundary-layer interactions at Mach 5.92

Fri, 01/26/2018 - 10:00

Author(s): Nathaniel Hildebrand, Anubhav Dwivedi, Joseph W. Nichols, Mihailo R. Jovanović, and Graham V. Candler

Above a critical angle, an oblique shock impinging on a Mach 5.92 boundary layer causes the resulting separated flow to become unstable. Direct numerical simulation and global stability analysis reveal the physical mechanism that drives this three-dimensional instability.

[Phys. Rev. Fluids 3, 013906] Published Fri Jan 26, 2018

Steady displacement of long gas bubbles in channels and tubes filled by a Bingham fluid

Thu, 01/25/2018 - 10:00

Author(s): Parsa Zamankhan, Shuichi Takayama, and James B. Grotberg

Creeping motion of a long bubble in 2D planar channels and axisymmetric tubes filled by a Bingham fluid is studied numerically. Bingham and capillary number effects on bubble shape, flow field, yield surfaces, and the wall shear stress profile are discussed and applied to human respiratory airways.

[Phys. Rev. Fluids 3, 013302] Published Thu Jan 25, 2018

Dynamics of jets produced by bursting bubbles

Thu, 01/25/2018 - 10:00

Author(s): Luc Deike, Elisabeth Ghabache, Gérard Liger-Belair, Arup K. Das, Stéphane Zaleski, Stéphane Popinet, and Thomas Séon

Bubble bursting is a ubiquitous phenomenon, impacting the climate by producing sea spray aerosols above the ocean, while also controlling the fineness of the effervescence of sparkling wine. Numerical and laboratory experiments are used to rationalize the velocity of jets formed by bubble bursting.

[Phys. Rev. Fluids 3, 013603] Published Thu Jan 25, 2018

Bursting and critical layer frequencies in minimal turbulent dynamics and connections to exact coherent states

Thu, 01/25/2018 - 10:00

Author(s): Jae Sung Park, Ashwin Shekar, and Michael D. Graham

A new investigation identifies frequencies in minimal channel flow relevant to critical layer dynamics displayed by exact coherent states and shows their predominance over bursting frequencies away from the wall. It is also shown that strong bursts are related to the instability of coherent states.

[Phys. Rev. Fluids 3, 014611] Published Thu Jan 25, 2018

Locomotion of a bioinspired flyer powered by one pair of pitching foils

Wed, 01/24/2018 - 10:00

Author(s): Xiang Zhang, Guowei He, Shizhao Wang, and Xing Zhang

In a numerical investigation of the flight dynamics and aerodynamics of a two-dimensional jellyfish-like ornithopter, three locomotion states are identified with the variation of control parameters. The responses of the ornithopter to physical and numerical perturbations are also examined.

[Phys. Rev. Fluids 3, 013102] Published Wed Jan 24, 2018

Key vortical structure causing laminar-turbulent transition in a boundary layer disturbed by a short-duration jet

Tue, 01/23/2018 - 10:00

Author(s): Joe Yoshikawa, Yu Nishio, Seiichiro Izawa, and Yu Fukunishi

Numerical simulations show that while a short-duration jet ejected into a Blasius boundary layer directly generates hairpin vortices with narrow legs, they themselves do not lead to turbulent transition. Generation, by vortex reconnection, of a hairpin vortex with widespread legs is key in the transition to turbulence.

[Phys. Rev. Fluids 3, 013904] Published Tue Jan 23, 2018

Experimental investigation of the wake behind a rotating sphere

Tue, 01/23/2018 - 10:00

Author(s): M. Skarysz, J. Rokicki, S. Goujon-Durand, and J. E. Wesfreid

Evolution of the flow regimes in the wake behind a streamwise rotating sphere was experimentally studied focusing on the Reynolds number versus rotation rate parameter plane. Four different regimes were observed in the wake and were investigated using modal decomposition and frequency analysis.

[Phys. Rev. Fluids 3, 013905] Published Tue Jan 23, 2018

Effective viscosity of a random mixture of fluids

Tue, 01/23/2018 - 10:00

Author(s): Benoît Noetinger, Laurène Hume, Robin Chatelin, and Philippe Poncet

The effective viscosity of mixtures is of interest for many applications. A model is proposed that relates this effective viscosity to minimal information regarding the microstructure of the mixture. This model is validated by means of direct numerical simulations of flows of these mixtures.

[Phys. Rev. Fluids 3, 014103] Published Tue Jan 23, 2018

Transitional region of a round synthetic jet

Mon, 01/22/2018 - 10:00

Author(s): Xi Xia and Kamran Mohseni

Experimental observations suggest the existence of an extended transitional region, as far as 30–50 diameter from a synthetic jet exit, where the spreading and decay rates are significantly enhanced over a continuous jet.

[Phys. Rev. Fluids 3, 011901(R)] Published Mon Jan 22, 2018

Rheology of suspensions of viscoelastic spheres: Deformability as an effective volume fraction

Mon, 01/22/2018 - 10:00

Author(s): Marco E. Rosti, Luca Brandt, and Dhrubaditya Mitra

Simulations show that a suspension of deformable incompressible spheres in a Newtonian fluid displays shear-thinning and that this can be understood in terms of a reduction of the effective volume fraction occupied by the suspended spheres due to their deformation.

[Phys. Rev. Fluids 3, 012301(R)] Published Mon Jan 22, 2018

Secondary flow vortical structures in a ${180}^{∘}$ elastic curved vessel with torsion under steady and pulsatile inflow conditions

Mon, 01/22/2018 - 10:00

Author(s): Mohammad Reza Najjari and Michael W. Plesniak

Multiple vortex-pair morphologies were studied using particle image velocimetry in steady and pulsatile flows through elastic curved vessels. Torsion effects were more profound than local vessel compliance (elasticity) effects. Torsion induces asymmetry in the vortical structures and causes like-signed vortices to merge.

[Phys. Rev. Fluids 3, 013101] Published Mon Jan 22, 2018

Aeroelastic deformation of a perforated strip

Mon, 01/22/2018 - 10:00

Author(s): M. Guttag, H. H. Karimi, C. Falcón, and P. M. Reis

The aerodynamic drag and consequent deformation of a perforated flexible strip are studied with a combination of wind-tunnel experiments and numerical simulations. Increasing the porosity of the strips causes a reduction in the local drag coefficient similar to that seen in rigid perforated plates.

[Phys. Rev. Fluids 3, 014003] Published Mon Jan 22, 2018

Hamiltonian bifurcation perspective on two interacting vortex pairs: From symmetric to asymmetric leapfrogging, period doubling, and chaos

Mon, 01/22/2018 - 10:00

Author(s): Brandon Whitchurch, Panayotis G. Kevrekidis, and Vassilis Koukouloyannis

Leapfrogging occurs, for example, in smoke or bubble rings. We model it in two dimensions with two interacting vortex pairs. Varying the vortices initial positions, we observe instabilities and bifurcations of leapfrogging along with other features including walkabout, braiding and chaotic motions.

[Phys. Rev. Fluids 3, 014401] Published Mon Jan 22, 2018

Turbulence intensities in large-eddy simulation of wall-bounded flows

Mon, 01/22/2018 - 10:00

Author(s): H. J. Bae, A. Lozano-Durán, S. T. Bose, and P. Moin

We study the effect of wall boundary conditions on turbulence intensities in the context of wall-modeled large-eddy simulations. It is shown that the use of a slip boundary condition at the wall alleviates the well known turbulence intensity over-/under-prediction in coarse large-eddy simulations.

[Phys. Rev. Fluids 3, 014610] Published Mon Jan 22, 2018

Publisher's Note: Poiseuille flow over a wavy surface [Phys. Rev. Fluids <b>2</b>, 124102 (2017)]

Mon, 01/22/2018 - 10:00

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

[Phys. Rev. Fluids 3, 019901] Published Mon Jan 22, 2018

Evolution of nonconformal Landau-Levich-Bretherton films of partially wetting liquids

Fri, 01/19/2018 - 10:00

Author(s): Michiel T. Kreutzer, Maulik S. Shah, Pravien Parthiban, and Saif A. Khan

Partially wetting thin films that are connected to plateau borders are described. The lifetimes of such films are found by matching the regimes of early capillary thinning and later collapse due to intermolecular forces.

[Phys. Rev. Fluids 3, 014203] Published Fri Jan 19, 2018

Structure of high and low shear-stress events in a turbulent boundary layer

Fri, 01/19/2018 - 10:00

Author(s): G. Gomit, R. de Kat, and B. Ganapathisubramani

The structure of high and low shear-stress events in a turbulent boundary layer is investigated by means of simultaneous wide-field particle image velocimetry and wall-shear stress measurements. Contributions of the small and large scales are discussed based on a scale decomposition of the velocity field.

[Phys. Rev. Fluids 3, 014609] Published Fri Jan 19, 2018

Impact of state-specific flowfield modeling on atomic nitrogen radiation

Thu, 01/18/2018 - 10:00

Author(s): Christopher O. Johnston and Marco Panesi

Removing typically-applied approximations (quasi-steady-state electronic levels and local escape factors) noticeably impacts the predicted shock-layer radiative heating to the afterbody region of Earth entry vehicles.

[Phys. Rev. Fluids 3, 013402] Published Thu Jan 18, 2018

Cascades of energy and helicity in axisymmetric turbulence

Thu, 01/18/2018 - 10:00

Author(s): Bo Qu, Aurore Naso, and Wouter J. T. Bos

Axisymmetric turbulence shares features with both two- and three-dimensional flows. A spectral analysis shows the presence of a dual energy-helicity cascade, with energy transferred to the large scales and helicity to the small ones.

[Phys. Rev. Fluids 3, 014607] Published Thu Jan 18, 2018

Secondary flows in turbulent boundary layers over longitudinal surface roughness

Thu, 01/18/2018 - 10:00

Author(s): Hyeon Gyu Hwang and Jae Hwa Lee

Inspection of spatial features of secondary flows in a turbulent boundary layer over longitudinal surface roughness shows that secondary flow size is mostly determined by the valley width and the rotational sense of secondary flows is affected by the turbulent transport term in the energy budget.

[Phys. Rev. Fluids 3, 014608] Published Thu Jan 18, 2018