Latest papers in fluid mechanics
Author(s): Zhi-Rui Zhou, You-Sheng Zhang, and Bao-Lin Tian
Implicit large eddy simulations of two-dimensional Rayleigh-Taylor instability at different density ratios (i.e., Atwood number A=0.05, 0.5, and 0.9) are conducted to investigate the late-time dynamics of bubbles. To produce a flow field full of bounded, semibounded, and chaotic bubbles, three probl...
[Phys. Rev. E 97, 033108] Published Thu Mar 22, 2018
Author(s): Taketo Ariki, Kyo Yoshida, Keigo Matsuda, and Katsunori Yoshimatsu
Heavy particle clustering in turbulence is discussed from both phenomenological and analytical points of view, where the −4/3 power law of the pair-correlation function is obtained in the inertial range. A closure theory explains the power law in terms of the balance between turbulence mixing and pr...
[Phys. Rev. E 97, 033109] Published Thu Mar 22, 2018
Author(s): Hyungwon John Park, Kevin O'Keefe, and David H. Richter
Rayleigh-Bénard convection is simulated to study the effects of inertial, nonisothermal particles on buoyancy-driven turbulent fluid. Distinct particle characteristics, such as gravitational settling and specific heat, are isolated to infer which are dominant in affecting the fluid.
[Phys. Rev. Fluids 3, 034307] Published Thu Mar 22, 2018
Author(s): Ralph J. Volino and Michael P. Schultz
A method for determining the wall shear stress under arbitrary streamwise pressure gradients and wall roughness conditions using Reynolds shear stress and mean velocity profile data is presented. Data from very near the wall are not required. The method is tested with experimental and direct numerical simulation data.
[Phys. Rev. Fluids 3, 034606] Published Thu Mar 22, 2018
Author(s): J. C. Serrano-García, S. Mendez-Díaz, and R. Zenit
The average properties of a bidisperse bubbly flow are studied experimentally. We find that the induced liquid velocity fluctuations are smaller than those expected from adding the monodisperse values for each size species, which indicates a strong dissipative interaction between species.
[Phys. Rev. Fluids 3, 034306] Published Wed Mar 21, 2018
Author(s): Michele Buzzicotti, Hussein Aluie, Luca Biferale, and Moritz Linkmann
The formation of intense quasi-2D cyclones characterizes the large-scale dynamics of any turbulent flow under strong rotation. A numerical study shows how 2D and 3D (homochiral) interactions cooperate for the inverse energy cascade.
[Phys. Rev. Fluids 3, 034802] Published Wed Mar 21, 2018
Author(s): Arnold J. T. M. Mathijssen, Raphaël Jeanneret, and Marco Polin
Cell interactions from predation to infection depend on direct contact and its duration. Experiments, simulations, and modeling show that for microswimmers contact is regulated by a competition between advection and diffusion akin to a generalized Taylor-dispersion phenomenon.
[Phys. Rev. Fluids 3, 033103] Published Tue Mar 20, 2018
Author(s): Jarrod Schiffbauer and Tengfei Luo
We investigate the nature of vapor bubble formation near a nanoscale-curved convex liquid-solid interface using two models: an equilibrium Gibbs model for homogenous nucleation, and a nonequilibrium dynamic van der Waals–diffuse-interface model for phase change in an initially cool liquid. Vapor bub...
[Phys. Rev. E 97, 033106] Published Mon Mar 19, 2018
Enhancement of the water flow velocity through carbon nanotubes resulting from the radius dependence of the friction due to electron excitations
Author(s): J. B. Sokoloff
Secchi et al. [Nature (London) 537, 210 (2016)] observed a large enhancement of the permeability and slip length in carbon nanotubes when the tube radius is of the order of 15 nm, but not in boron nitride nanotubes. It will be pointed out that none of the parameters that appear in the usual molecula...
[Phys. Rev. E 97, 033107] Published Mon Mar 19, 2018
Author(s): Zhuoyu Zhou and Rajat Mittal
The Aplysia, also known as ’sea hare’, is a marine mollusc that swims via large-amplitude flapping. With flow simulations we find a unique pattern in its wake of three vortex ring-like structures which overcome body drag. Swimming performance, however, appears to lag behind that of related species.
[Phys. Rev. Fluids 3, 033102] Published Fri Mar 16, 2018
Author(s): James T. Jenkins and Alexandre Valance
A two-phase continuum theory is derived for grains that collide with and jump above a bed of sand while accelerated by a turbulent wind. The resulting system of equations and boundary conditions for unsteady, uniform and steady, nonuniform flows is solved to determine saturation times and lengths.
[Phys. Rev. Fluids 3, 034305] Published Fri Mar 16, 2018
Fluid particles only separate exponentially in the dissipation range of turbulence after extremely long times
Author(s): Rohit Dhariwal and Andrew D. Bragg
While it is usually assumed that fluid particles separate exponentially in the dissipation range, this need not be true and the evidence for it is controversial. A re-examination of this old problem shows that fluid particles do indeed separate exponentially but only after extremely long times.
[Phys. Rev. Fluids 3, 034604] Published Fri Mar 16, 2018
Author(s): John A. Palmore, Jr. and Olivier Desjardins
Linear forcing is commonly used to simulate isotropic turbulence in physical space. Here we modify the forcing term to act on a low-pass filtered velocity field and obtain a 60% increase of the Taylor microscale Reynolds number on the same mesh. An extension is also made to scalar mixing.
[Phys. Rev. Fluids 3, 034605] Published Fri Mar 16, 2018
Author(s): Hari C. Ghimire and Sean C. C. Bailey
Circulation loss from a vortex immersed in turbulent surroundings occurs in a nondiffusive manner. Experiments are used to connect the circulation loss to instantaneous instances of vorticity stripping from the vortex core.
[Phys. Rev. Fluids 3, 034702] Published Fri Mar 16, 2018
Author(s): Bruce R. Sutherland, Kristen Cote, Youn Sub (Dominic) Hong, Luke Steverango, and Chris Surma
Lock-release experiments of viscous gravity currents (VGC) of glycerol released in water find different dynamics from air release. The current advance is nearly constant, then nearly halts as the head flattens, in contrast to known self-similar VGC where the front advances as a 1/5 power of time.
[Phys. Rev. Fluids 3, 034101] Published Thu Mar 15, 2018
Author(s): Federico Dalla Barba and Francesco Picano
An investigation of the evaporation of dilute droplets within a turbulent spatial-developing jet via direct numerical simulation is presented. A strong droplet preferential segregation is found, which affects the overall vaporization process and induces a wide spreading of the droplet-size spectrum.
[Phys. Rev. Fluids 3, 034304] Published Thu Mar 15, 2018
Author(s): Y. Ibrahim, R. Golestanian, and T. B. Liverpool
A study of the swimming speed of rodlike self-propelled colloids driven by reactions on their surfaces finds that even for very thin swimmers, cylinders are not the same as ellipsoids with the same aspect ratio. Cylinders swim faster.
[Phys. Rev. Fluids 3, 033101] Published Wed Mar 14, 2018
Experimental observations of the three-dimensional wake structures and dynamics generated by a rigid, bioinspired pitching panel
Author(s): Justin T. King, Rajeev Kumar, and Melissa A. Green
The wake created by a trapezoidal pitching panel displays a variety of dynamics and behaviors. Results show that a chain of highly three-dimensional, alternating vortex rings is shed from the trailing edge. These rings interact with each other in a manner that is dependent on Strouhal number.
[Phys. Rev. Fluids 3, 034701] Published Wed Mar 14, 2018
Author(s): Mayuko Murano and Ko Okumura
Experimental observations of bubbles bursting between two confining plates find a constant speed of the rim and a tip that does not grow. The dynamics is governed by surface energy transformed into viscous dissipation. Left and right tip shapes look different due to a difference in focal point.
[Phys. Rev. Fluids 3, 031601(R)] Published Tue Mar 13, 2018
Author(s): Ory Schnitzer and Ehud Yariv
A simple leading-order approximation for the slip-length tensor of an arbitrary mesh geometry is obtained in the limit of small solid-fraction of the mesh.
[Phys. Rev. Fluids 3, 032201(R)] Published Tue Mar 13, 2018