Physical Review Fluids
Modal analysis with proper orthogonal decomposition of hypersonic separated flows over a double wedge
Author(s): Ozgur Tumuklu, Deborah A. Levin, and Vassilis Theofilis
A study combining direct simulation Monte Carlo simulations with window proper orthogonal decomposition investigates the temporal characteristics of unsteady, laminar shock boundary-layer interactions for different gas mixtures for an Edney type-IV flow.
[Phys. Rev. Fluids 4, 033403] Published Tue Mar 19, 2019
Author(s): Truong Pham and Satish Kumar
Colloidal particles inside an evaporated droplet on a solid substrate are often preferentially deposited at the droplet contact line, a phenomenon known as the coffee-ring effect. A study shows how this phenomenon is affected by the permeability of the substrate.
[Phys. Rev. Fluids 4, 034004] Published Tue Mar 19, 2019
Author(s): Ruiying Li, Jacques Borée, Bernd R. Noack, Laurent Cordier, and Fabien Harambat
We propose a windward bi-frequency control strategy to manipulate experimentally the wake past a yawed car model using pulsed jets. By varying the low frequency value in the actuation, we can provide a complete authority for the manipulation of the mean wake orientation and reduce drag.
[Phys. Rev. Fluids 4, 034604] Published Tue Mar 19, 2019
Author(s): Matthew Butler, Finn Box, Thomas Robert, and Dominic Vella
Inspired by the droplet-mediated adhesion of insects, the adhesion between soft and rigid surfaces mediated by a droplet is studied. Deformability allows for enhanced adhesion as well as new routes for “unsticking,” but the dynamics of adhesion also plays a role.
[Phys. Rev. Fluids 4, 033601] Published Mon Mar 18, 2019
Author(s): C. M. Boyce, A. Penn, A. Padash, M. Lehnert, K. P. Pruessmann, and C. R. Müller
Rapid magnetic resonance imaging shows how bubbles collapse in fluidized beds as a result of gas channeling to neighboring bubbles.
[Phys. Rev. Fluids 4, 034303] Published Mon Mar 18, 2019
Importance of small-scale anisotropy in the turbulent/nonturbulent interface region of turbulent free shear flows
Author(s): O. R. H. Buxton, M. Breda, and K. Dhall
Turbulent flows are often bounded by nonturbulent fluid with a sharp interface between the two flow states. Drawing a parallel between this interface and the wall in a wall-bounded flow and similarly, to wall-bounded turbulence, shows the importance of the anisotropy very close to the interface.
[Phys. Rev. Fluids 4, 034603] Published Mon Mar 18, 2019
Author(s): X. I. A. Yang, S. Zafar, J.-X. Wang, and H. Xiao
A study shows that when trained using channel flow data at just one Reynolds number and informed with known flow physics, the neural network works robustly as a wall model in large-eddy simulation (LES) of channel flow at any Reynolds number. It also outperforms the equilibrium wall model in LES of a 3D boundary layer flow.
[Phys. Rev. Fluids 4, 034602] Published Fri Mar 15, 2019
Orientation dependent elastic stress concentration at tips of slender objects translating in viscoelastic fluids
Author(s): Chuanbin Li, Becca Thomases, and Robert D. Guy
The elastic stress generated moving in a purely viscous flow around a slender cylinder is found to be large near the tips, and larger when the flow is parallel to the axis.
[Phys. Rev. Fluids 4, 031301(R)] Published Thu Mar 14, 2019
Author(s): Y. Ben-Ami and A. Manela
The effect of heat-flux conditions on the Rayleigh-Bénard convection in a rarefied gas is investigated, extending instability to higher rarefaction rates compared with the isothermal walls case. The deviation from the Boussinesq limit with increasing compressibility is analyzed.
[Phys. Rev. Fluids 4, 033402] Published Thu Mar 14, 2019
Author(s): Allison Lee and Julie Crockett
Evanescent regions exist in numerous areas of the deep ocean where the stratification also varies with depth. Using theoretical predictions and experiments, the kinetic energy density in propagating internal waves generated from these evanescent regions is explored.
[Phys. Rev. Fluids 4, 034803] Published Thu Mar 14, 2019
Author(s): Mariana Rodríguez-Hakim, Joseph M. Barakat, Xingyi Shi, Eric S. G. Shaqfeh, and Gerald G. Fuller
Evaporation of a volatile solvent induces solutocapillary Marangoni flows by creating gradients in species concentration and surface tension. These flows are experimentally and theoretically investigated in sub-micron films at dilute solute concentrations where Van der Waals effects are important.
[Phys. Rev. Fluids 4, 034002] Published Wed Mar 13, 2019
Author(s): B. Dastvareh and J. Azaiez
Chemo-hydrodynamic instabilities are investigated in the presence of nano-catalysts. The additional transport mechanism of nano-catalysts as a result of the heat of reaction, called thermophoresis, has affected both the dynamics and the amount of chemical products.
[Phys. Rev. Fluids 4, 034003] Published Wed Mar 13, 2019
Author(s): Luke R. Smith and Anya R. Jones
Vortex shedding patterns are examined on a yawed wing pitching in reverse flow. The yawed wing exhibits suppression of its secondary flow structures compared to an unyawed wing. Various physical mechanisms, particularly spanwise flow, are evaluated to explain the shedding pattern of the yawed wing.
[Phys. Rev. Fluids 4, 034703] Published Tue Mar 12, 2019
Author(s): Justin Péméja, Baudouin Géraud, Catherine Barentin, and Marie Le Merrer
The slip velocity of jammed polymer microgels is measured as the wall stress is increased by 4 orders of magnitude. The friction law exhibits a transition in slip regimes, from a nonlinear to a linear scaling, linked to two distinct dissipation mechanisms at the scale of the soft elements.
[Phys. Rev. Fluids 4, 033301] Published Mon Mar 11, 2019
Author(s): Rohit Dhariwal and Andrew D. Bragg
Direct numerical simulations are used to study the relative dispersion of settling, bidisperse inertial particles in isotropic turbulence. It is found that gravity can significantly enhance the relative dispersion, not only in the direction parallel, but even in the direction normal to gravity.
[Phys. Rev. Fluids 4, 034302] Published Mon Mar 11, 2019
Transition from convection rolls to large-scale cellular structures in turbulent Rayleigh-Bénard convection in a liquid metal layer
Author(s): Megumi Akashi, Takatoshi Yanagisawa, Yuji Tasaka, Tobias Vogt, Yuichi Murai, and Sven Eckert
A new coherent structure appears on turbulent Rayleigh-Bénard convection in a liquid metal layer; transitions to large-scale cellular structures from oscillatory roll structures occur with Rayleigh numbers. A scaling law describing characteristic length of the structures is suggested.
[Phys. Rev. Fluids 4, 033501] Published Fri Mar 08, 2019
Author(s): Field Manar and Anya R. Jones
Wake characteristics and force production of a flat plate wing starting from rest at high incidence are examined. Circulation production at the wing leading edge is shown to be coupled to wing kinematics and the wake state. Several potential flow models are compared to experiments.
[Phys. Rev. Fluids 4, 034702] Published Fri Mar 08, 2019
Author(s): M.-W. Ge, Xiang I. A. Yang, and Ivan Marusic
A study on the scaling implications of the attached eddy hypothesis and the large deviation theory on the velocity probability distribution function (PDF) concludes that, when scaled properly, the remote tails of the streamwise and spanwise velocity PDF collapse for flows in the logarithmic layer.
[Phys. Rev. Fluids 4, 034101] Published Thu Mar 07, 2019
Author(s): Daniel P. Brzozowski, Bojan Vukasinovic, and Ari Glezer
Static and transient responses of an airfoil to bi-directional flow control actuation at the trailing-edge are investigated in wind tunnel experiments. Flow field measurements elucidate control of aerodynamic loads through regulation of trapped vorticity concentrations upstream of the trailing edge.
[Phys. Rev. Fluids 4, 034601] Published Thu Mar 07, 2019
Flow force measurements and the wake transition in purely inline vortex-induced vibration of a circular cylinder
Author(s): Tyler D. Gurian, Todd Currier, and Yahya Modarres-Sadeghi
We find a novel shedding mode (Alternating-Symmetric) in the vortex-induced vibration response of a cylinder free to oscillate in the inline direction. In this mode, two vortices of opposite sign are shed simultaneously from two sides of the oscillating cylinder, but their sizes alternate per cycle.
[Phys. Rev. Fluids 4, 034701] Published Thu Mar 07, 2019