Latest papers in fluid mechanics

Stability boundaries for the Rayleigh-Taylor instability in accelerated elastic-plastic solid slabs

Physical Review E - Thu, 12/12/2019 - 10:00

Author(s): A. R. Piriz, S. A. Piriz, and N. A. Tahir

The linear theory of the incompressible Rayleigh-Taylor instability in elastic-plastic solid slabs is developed on the basis of the simplest constitutive model consisting in a linear elastic (Hookean) initial stage followed by a rigid-plastic phase. The slab is under the action of a constant acceler...

[Phys. Rev. E 100, 063104] Published Thu Dec 12, 2019

Gravity induced formation of spinners and polar order of spherical microswimmers on a surface

Physical Review Fluids - Thu, 12/12/2019 - 10:00

Author(s): Zaiyi Shen and Juho S. Lintuvuori

When squirmer type swimmers sediment on a flat surface, the near field hydrodynamic interactions lead to the formation of small spinners at low concentrations. Higher surface coverage results in a polar order of the swimmers and a particle vortex is observed when confined by a circular wall.

[Phys. Rev. Fluids 4, 123101] Published Thu Dec 12, 2019

Role of extensional rheology on droplet bouncing

Physical Review Fluids - Thu, 12/12/2019 - 10:00

Author(s): Min Y. Pack, Angela Yang, Antonio Perazzo, Boyang Qin, and Howard A. Stone

Experiments show that the addition of polymers in droplets enhances the droplet rebound effect when bouncing on a thin film of air.

[Phys. Rev. Fluids 4, 123603] Published Thu Dec 12, 2019

Hydrodynamic response of a surfactant-laden interface to a radial flow

Physical Review Fluids - Thu, 12/12/2019 - 10:00

Author(s): T. Bickel, J.-C. Loudet, G. Koleski, and B. Pouligny

The Stokes flow of a submerged jet directed toward a free interface is investigated theoretically. The presence of a minute amount of surface-active agents drastically modifies the hydrodynamic response of the interface.

[Phys. Rev. Fluids 4, 124002] Published Thu Dec 12, 2019

Rotor boundary layer development in a two-stage compressor

Physics of Fluids - Thu, 12/12/2019 - 02:39
Physics of Fluids, Volume ISPF2020, Issue 1, March 2020.
This experimental study provides striking examples of the complex flow and turbulence structures resulting from blade–wake and wake–wake interactions in a multistage turbomachine. Particle image velocimetry measurements were performed within the second-stage rotors of a two-stage compressor. The first-stage stator wake is distorted and produces a kink structure in the second-stage rotor blades passage. This kink, also called a turbulent hot spot, with concentrated vorticity, high turbulence levels, and high turbulence kinetic energy, is caused by the interaction between the first-stage rotor wake and the stator wake. A high-speed region and a low-speed region are observed around the turbulent hot spot. The perturbation velocity is counterclockwise around the turbulent hot spot, with a magnitude much larger than that in the wake. The turbulent hot spot is more unstable and active than the wake and, thus, might play a pivotal role in the passage flow. The high turbulence and the negative jet behavior of the wake dominate the interaction between the unsteady wake and the separated boundary layer on the suction surface of the blade. When the upstream wake impinges on the blade, the boundary layer thickness first increases owing to the presence of the negative jet, and a thickened boundary layer region in the form of a turbulent spot is formed because of the high turbulence intensity in the wake. Then, the boundary layer gradually becomes thinner because of the presence of a calmed region that follows the thickened boundary layer region. Finally, the boundary layer gradually thickens again and recovers to separation. Thus, the boundary layer thickness is periodic in a wake passing cycle.

Physics of nanoscale immiscible fluid displacement

Physical Review Fluids - Wed, 12/11/2019 - 10:00

Author(s): Gerald J. Wang, Angelo Damone, Francesco Benfenati, Pietro Poesio, Gian Paolo Beretta, and Nicolas G. Hadjiconstantinou

At the nanoscale, and in particular in the presence of slip, hydrodynamic bending of interfaces between immiscible liquids becomes negligible. The dynamic contact angle is then governed by the Molecular Kinetic Theory (MKT) of Blake and collaborators.

[Phys. Rev. Fluids 4, 124203] Published Wed Dec 11, 2019

Mass transfer from a cylindrical body in a linear ambient velocity distribution

Physical Review Fluids - Wed, 12/11/2019 - 10:00

Author(s): Ehud Yariv

Asymptotic methods and conformal mappings are used to study mass or heat transport from a particle that is subject to a weak flow.

[Phys. Rev. Fluids 4, 124503] Published Wed Dec 11, 2019


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