Physical Review Fluids
Author(s): D. Bauer, L. Talon, Y. Peysson, H. B. Ly, G. Batôt, T. Chevalier, and M. Fleury
Experiments and three-dimensional numerical simulations of yield stress fluids in heterogeneous porous media show that, as a result of this disorder, the fluid flows through a single channel near a critical pressure. Beyond that, the number of open channels increases with the pressure applied.
[Phys. Rev. Fluids 4, 063301] Published Wed Jun 05, 2019
Author(s): Y.-N. Young, Yoichiro Mori, and Michael J. Miksis
When a poroelastic spherical drop is under a uniaxial extension flow or a shear flow, the elastic network deforms in response to the external fluid viscous stress. A small-deformation analysis is conducted to investigate effects of interfacial slip and permeability on flow around the drop.
[Phys. Rev. Fluids 4, 063601] Published Wed Jun 05, 2019
Author(s): Kai Fukami, Yusuke Nabae, Ken Kawai, and Koji Fukagata
Machine-learning-based turbulence generators are developed to generate unsteady inflow conditions for turbulent flow simulations. The proposed method can provide inflow conditions with reasonable turbulence statistics without spurious periodicity and at a low computational cost.
[Phys. Rev. Fluids 4, 064603] Published Tue Jun 04, 2019
Author(s): T. Lyubimova, A. Ivantsov, Y. Garrabos, C. Lecoutre, and D. Beysens
Coupled Faraday waves can develop under weightlessness on liquid-vapor bands induced by vibrations. The instability appears above a threshold that is determined by theoretical analysis and numerical simulation. It compares well with sounding rocket experiments in CO2 near its critical point.
[Phys. Rev. Fluids 4, 064001] Published Mon Jun 03, 2019
Author(s): Lei Fang and Nicholas T. Ouellette
In many geophysical situations, variable bathymetry can affect surface transport and mixing. Experiments show that the effect of bathymetry is to produce a porous transport barrier leading to asymmetric transport. These results may help to explain the dynamics of phenomena such as ocean dead zones.
[Phys. Rev. Fluids 4, 064501] Published Mon Jun 03, 2019
Author(s): Jingyuan Yang, Toshiyuki Gotoh, Hideaki Miura, and Takeshi Watanabe
Statistical properties of an incompressible passive vector in isotropic turbulence are compared with the velocity and passive scalar in order to explore the physics behind their differences and similarities.
[Phys. Rev. Fluids 4, 064601] Published Mon Jun 03, 2019
Author(s): W. Sosa-Correa, R. M. Pereira, A. M. S. Macêdo, E. P. Raposo, D. S. P. Salazar, and G. L. Vasconcelos
A theoretical framework, the H-theory, is applied to describe the skewed non-Gaussian distribution of velocity increments as a weighted mixture of asymmetric Gaussians. The weighing distribution is obtained from a hierarchical stochastic model of intermittency. Good agreement with direct numerical simulation data is found.
[Phys. Rev. Fluids 4, 064602] Published Mon Jun 03, 2019
Author(s): J. P. Pascal, S. J. D. D'Alessio, and E. Ellaban
Adding surfactant to clean fluid stabilizes the inclined flow. A theoretical study shows that beyond a critical level the flow is destabilized as more surfactant is added due to desorption from the surface. If the mass density of the fluid increases with surfactant concentration in the bulk, a later stabilizing stage occurs.
[Phys. Rev. Fluids 4, 054004] Published Fri May 31, 2019
Author(s): Antoine Naillon, Clément de Loubens, William Chèvremont, Samuel Rouze, Marc Leonetti, and Hugues Bodiguel
Quantitative experimental measurements are used to test the ability of theoretical development to predict the transverse velocity migration of particles in a confined Poiseuille flow, according to the viscoelastic constitutive parameters of dilute polymer solutions.
[Phys. Rev. Fluids 4, 053301] Published Thu May 30, 2019
Author(s): K. Kato, T. Kawata, P. H. Alfredsson, and R. J. Lingwood
Experiments show that crossflow vortices in the boundary layer on a rotating wide cone start to meander before breakdown. The structural development of the overturning process of these vortices, where high-momentum upwelling of the vortices leads to transition to turbulence, is described in detail.
[Phys. Rev. Fluids 4, 053903] Published Thu May 30, 2019
Coexistence of multiple long-time solutions for two-dimensional laminar flow past a linearly sprung circular cylinder with a rotational nonlinear energy sink
Author(s): Antoine B. Blanchard, Lawrence A. Bergman, Alexander F. Vakakis, and Arne J. Pearlstein
Phase diagram showing the variation of the number of long-time solutions with Re and a dimensionless measure of spring stiffness. Each combination of symbol shape and color indicates a different set of such solutions, with the pentagons corresponding to three unsteady solutions and one steady one.
[Phys. Rev. Fluids 4, 054401] Published Thu May 30, 2019
Author(s): F. Laadhari
A refinement of the logarithmic law for the mean velocity in canonical wall-bounded turbulent flows is presented. The relevant length scale in the overlap region is found to be based on the weighted mean velocity gradient instead of the classical length scale based on the wall friction velocity.
[Phys. Rev. Fluids 4, 054605] Published Thu May 30, 2019
Author(s): Tie Wei
Reexamination of some direct numerical simulation data for a turbulent differentially heated vertical channel finds that the components of the Reynolds stress scale with the product of the friction velocity and the maximum mean flow.
[Phys. Rev. Fluids 4, 051501(R)] Published Tue May 28, 2019
Author(s): Peter B. Weichman
Equilibrium properties of axisymmetric flow in cylindrical (Taylor-Couette) geometries are studied using the methods of statistical mechanics. The system is constrained by an infinite number of conservation laws, leading to an intricate interplay between the toroidal (σ) and poloidal (ξ) flow fields.
[Phys. Rev. Fluids 4, 054703] Published Tue May 28, 2019
Author(s): Bradley Gibeau, Charles Robert Koch, and Sina Ghaemi
Active control of vortex shedding from a blunt trailing edge is achieved experimentally using piezoelectric actuators. The system can suppress and amplify the vortex shedding pattern in the wake, as well as force near-wake symmetry. An application of closed-loop control is also demonstrated.
[Phys. Rev. Fluids 4, 054704] Published Tue May 28, 2019
Three-dimensional visualization of viscous fingering for non-Newtonian fluids with chemical reactions that change viscosity
Author(s): Sotheavuth Sin, Tetsuya Suekane, Yuichiro Nagatsu, and Anindityo Patmonoaji
Three-dimensional viscous fingering for miscible non-Newtonian fluids with and without chemical reactions were studied with a microfocus X-ray computed tomography scanner. We find that the area fraction of injected fluid in the reactive cases was lower than that in the nonreactive cases.
[Phys. Rev. Fluids 4, 054502] Published Fri May 24, 2019
Author(s): D. R. Brumley and T. J. Pedley
A dense planar array of spherical microswimmers is studied analytically and numerically using pairwise lubrication interactions. Suspension dynamics are mediated through gravitational torques exerted on the cells and cell-cell repulsive forces, and they reveal stable, oscillatory, and chaotic states.
[Phys. Rev. Fluids 4, 053102] Published Wed May 22, 2019
Vortex-dynamical interpretation of anti-phase and in-phase flickering of dual buoyant diffusion flames
Author(s): Tao Yang, Xi Xia, and Peng Zhang
A study finds that for two adjacent buoyant flames the flickering mode transition from in-phase to anti-phase is caused by a transition of the inner-side vortex pattern from symmetric to staggered. This mechanism is similar to the instability in the wake of a bluff body that initiates the Karman vortex street.
[Phys. Rev. Fluids 4, 053202] Published Wed May 22, 2019
Author(s): N. E. Sujovolsky, G. B. Mindlin, and P. D. Mininni
A low dimensional model for stratified turbulence predicts the existence of invariant manifolds for the evolution of temperature and velocity gradients. Fluid elements evolve preferentially along these manifolds, associated with stable regions and with regions prone to develop local convection.
[Phys. Rev. Fluids 4, 052402(R)] Published Mon May 20, 2019
Author(s): Antoine Blanchard and Themistoklis P. Sapsis
The Optimally Time-Dependent (OTD) modes, a set of deformable orthonormal modes that track transient instabilities, are incorporated into a robust, inexpensive control algorithm that can steer any trajectory of a high-dimensional nonlinear system toward a fixed point of the governing equations.
[Phys. Rev. Fluids 4, 053902] Published Mon May 20, 2019