Latest papers in fluid mechanics

Flow-induced deformation of kirigami sheets

Physical Review Fluids - Tue, 02/22/2022 - 10:00

Author(s): Tom Marzin, Kerian Le Hay, Emmanuel de Langre, and Sophie Ramananarivo

Kirigami cutting technique turns inextensible sheets into highly stretchable devices via the opening of pores. This work investigates experimentally the deformation of such poro-elastic structures in a water flow. We show that the cut pattern allows tailoring the magnitude of sheet expansion, by providing a simple and robust way to tune mechanical properties. But importantly, stretched kirigami sheets feature a three-dimensional mesostructure that dictates the direction of local fluid forces, notably leading here to asymmetric deformation of symmetric planar sheets.

[Phys. Rev. Fluids 7, 023906] Published Tue Feb 22, 2022

Effects of double orifice spacing on bubble behaviors and hydrodynamics in gas-liquid-solid systems through VOF-DEM method

Physical Review Fluids - Tue, 02/22/2022 - 10:00

Author(s): Haozhe Zhang, Na Zhao, Xiaotong Luo, and Jingtao Wang

The volume of fluid and discrete element model (VOF-DEM) method is employed to calculate the formation and rising of double bubbles generated through two different orifices in a gas-liquid-solid flow system. The deviation and coalescence of bubble queues which occur during the bubble rising process are discussed and analyzed with velocity vector diagrams. By comparing when particles are laid at the bottom or settling, it is found that free settlement of particles can weaken the deviation of the bubble queues. Moreover, finding a suitable distance between two orifices for enhanced particle entrainment under different air in-taking velocities is also studied.

[Phys. Rev. Fluids 7, 024303] Published Tue Feb 22, 2022

Effect of viscous-convective subrange on passive scalar statistics at high Reynolds number

Physical Review Fluids - Tue, 02/22/2022 - 10:00

Author(s): Kedar Prashant Shete, David J. Boucher, James J. Riley, and Stephen M. de Bruyn Kops

In modeling turbulent mixing at high Reynolds number (Re), the small-scale statistics of a passive scalar are assumed similar to those of the velocity. Research shows this to be invalid at either high Re or high Schmidt number individually. We hypothesize that both inertial-convective and viscous-convective subranges are needed for sufficient scale separation in both velocity and scalar fields, such that small-scale statistics of the scalar approach those of the velocity. We explore this using direct numerical simulations of up to 142563 and find that at high Taylor Reynolds number of 633, similarity may be assumed between velocity and scalar statistics for mixing in water, but not in air.

[Phys. Rev. Fluids 7, 024601] Published Tue Feb 22, 2022

Suppression of vortex-induced vibration of a circular cylinder by a finite-span flexible splitter plate

Physical Review Fluids - Tue, 02/22/2022 - 10:00

Author(s): Guo-Peng Cui and Li-Hao Feng

We present experiment and analysis of the effectiveness of a flexible splitter plate in the suppression of vortex-induced vibration (VIV) of a circular cylinder. The important finding is that it is not necessary to suppress VIV by a full-span flexible splitter plate, while efficient control can be achieved by a finite-span one. The fluid-structure interaction and control mechanism are revealed by analysis of wake evolution and force characteristics.

[Phys. Rev. Fluids 7, 024708] Published Tue Feb 22, 2022

Wake identification of stratified flows using dynamic mode decomposition

Physical Review Fluids - Tue, 02/22/2022 - 10:00

Author(s): Chan-Ye Ohh and Geoffrey R. Spedding

In a density-stratified fluid, the wakes generated by a submerged body or topography can be placed into a number of distinct flow regimes, depending on the balance of forces represented by the Reynolds number, Re, and Froude number, Fr. Here we propose a dynamic mode decomposition (DMD) based classifier to automatically sort stratified wakes based on their strongest DMD modes. The performance of the classifier in a test range of low {Re, Fr} yields insights into the development of further data-driven methods for the more challenging and fully turbulent wakes expected from bodies and geographical features.

[Phys. Rev. Fluids 7, 024801] Published Tue Feb 22, 2022

Canonical orbits for rapidly deforming planar microswimmers in shear flow

Physical Review Fluids - Fri, 02/18/2022 - 10:00

Author(s): Eamonn A. Gaffney, Mohit P. Dalwadi, Clément Moreau, Kenta Ishimoto, and Benjamin J. Walker

Classically, the rotation of ellipsoids in shear Stokes flow is captured by Jeffery’s orbits. Here, we demonstrate that Jeffery’s orbits also describe high-frequency shape-deforming swimmers moving in the plane of a shear flow. In doing so, we support the use of these simple models for capturing shape-changing swimmer dynamics in studies of active matter and highlight the ubiquity of ellipsoid-like dynamics in complex systems.

[Phys. Rev. Fluids 7, L022101] Published Fri Feb 18, 2022


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