Physical Review Fluids

Journal: Physical Review Fluids

Abbreviation

Phys. Rev. Fluids

Publisher

American Physical Society

ISSN

2469-990X

Show all metadata

Search Results

Publications 1 - 10 of 54

Rebounds of deformed cavitation bubbles
Supponen, Outi; Obreschkow, Danail; Farhat, Mohamed (2018)
Physical Review Fluids
Diffusioosmotic flow in a soft microfluidic configuration induces fluid-structure instability
Maroundik, Nataly; Ilssar, Dotan; Boyko, Evgeniy (2025)
Physical Review Fluids
Diffusioosmotic flow arises in microfluidic configurations due to solute concentration gradients. In soft microfluidic channels, internal pressure gradients generated by diffusioosmotic flow to conserve mass result in elastic deformation of the channel walls, triggering fluid–structure interaction. In this work, we analyze the fluid–structure interaction between diffusioosmotic flow of an electrolyte solution and a deformable microfluidic channel. We provide insight into the physical behavior of the system by developing a reduced-order model, in which a viscous film is confined between a rigid bottom surface and an elastic top substrate, represented as a rigid plate connected to a linear spring. Considering a slender configuration and applying the lubrication approximation, we derive a set of two-way coupled governing equations describing the evolution of the fluidic film thickness and the solute concentration. Our theoretical predictions show that above a certain concentration gradient threshold, negative pressures induced by diffusioosmotic flow give rise to fluid–structure instability, causing the elastic top substrate to collapse onto the bottom surface. We employ theoretical analysis to elucidate the underlying physical mechanisms for the onset of fluid–structure instability by performing a linear stability analysis of the system and identifying three distinct dynamic regimes.We validate our theoretical results with finite-element simulations and find excellent agreement. The understanding of this instability is of fundamental importance for improving the control and design of microfluidic systems driven by diffusioosmotic flow and containing soft elements.
Exploring the size ratio impact on an intruder segregating in bedload transport
Dedieu, Benjamin; Rousseau, Hugo; Chauchat, Julien; et al. (2024)
Physical Review Fluids
Vertical size segregation in bedload transport impacts the sediment rate and the river bed morphology. To better account for this process in sediment transport models, it is essential to understand the mechanisms acting at the grain scale. This paper focuses on the behavior of a single large particle called the intruder, segregating upwards in a granular bed made of smaller mono-dispersed beads, during bedload transport. Experiments were carried out in a narrow flume, where the distance between the sidewalls was of the order of the intruder diameter. The latter was initially buried a few diameters below the bed surface. While supplying the flume with constant rates of small beads and water, we used a high-speed camera and image analysis techniques to monitor both the trajectory of the intruder and the velocity of the granular bed. We performed approximately 300 experiments with six size ratios (large to small) ranging from 1.25 to 3.0 to get statistically representative intruder trajectories. This extensive and unusual data set allows for a more thorough validation of the observations made in the work of Rousseau et al. [Phys. Rev. Fluids 7, 064305 (2022)2469-990X10.1103/PhysRevFluids.7.064305]. Specifically, our results highlight the transition in the intruder behavior occurring around a size ratio of 2. Below this value, the intruder spatial trajectory exhibits a greater variability and gets steeper as the size ratio increases. Above the value of 2 and whatever the size ratio, the spatial trajectory is almost linear with a constant slope, and the time taken by the intruder to reach the bed surface increases with the size ratio. In addition, our extensive data set reveals insights into the intruder kinematics. Notably, we observed that the intruder undergoes a size-ratio-dependent streamwise velocity lag with respect to the bulk flow. Based on these observations, we propose a simple kinematic model which predicts the segregation duration of an intruder in bedload transport, incorporating a parameter representing the linear trajectory and a drift coefficient characterizing the streamwise velocity lag. Both parameters introduce a size ratio dependency based on our statistical analysis.
Experimental study of concentrated particle transport in successively bifurcating vessels
Li, Yinghui; Amili, Omid; Coletti, Filippo (2022)
Physical Review Fluids
The flow features in branching networks are fundamental for the understanding of transport processes in respiratory and cardiovascular systems. Specifically for tumor embolization, the ability to predict the fate of finite-size particles in bifurcating vessels is highly desirable for improving embolization efficacy. Most past studies focused on very dilute regimes in which particles are not expected to interact with each other. In the present study, we use particle tracking velocimetry to investigate the spatial distribution, velocity, acceleration, and dispersion of finite-size particles in a four-generation bifurcating model. We consider a regime especially relevant to vascular embolization: a physiologic range of bulk flow Reynolds number and a suspension of neutrally buoyant particles with a diameter about 10 times smaller than the parent vessel diameter, reaching solid volume fractions up to 2%. We investigate how particles distribute among the distal branches and the influence of the release location. In addition, the effect of particle volume fraction is studied through Lagrangian statistics of the particle trajectories. Our results show the remarkable influence of particle concentration on particle transport in several ways. The particle traveling speed, acceleration, and dispersion are inhibited by the increasing particle volume fraction due to interparticle interactions. Importantly, the particles travel preferentially to the medial branches rather than to the lateral ones despite the uniform distribution of the distal volumetric flow rate. The findings provide insights relevant to the optimization of targeted drug delivery in embolization settings.
Progressive Monte Carlo rendering of atmospheric flow features across scales
Günther, Tobias; Kuhn, Alexander; Hege, Hans-Christian; et al. (2017)
Physical Review Fluids
This paper is associated with a poster winner of a 2016 APS/DFD Milton van Dyke Award for work presented at the DFD Gallery of Fluid Motion. The original poster is available from the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2016.GFM.P0030
Numerical investigation of quasistatic magnetoconvection with an imposed horizontal magnetic field
Calkins, Michael A.; Alrefae, Talal; Hernandez, Angel; et al. (2023)
Physical Review Fluids
Quasistatic Rayleigh-Bénard convection with an imposed horizontal magnetic field is investigated numerically for Chandrasekhar numbers up to Q=106 with stress-free boundary conditions. Both Q and the Rayleigh number (Ra) are varied to identify the various dynamical regimes that are present in this system. We find three primary regimes: (i) a two-dimensional (2D) regime in which the axes of the convection rolls are oriented parallel to the imposed magnetic field; (ii) an anisotropic three-dimensional (3D) regime; and (iii) a mean flow regime characterized by a large scale horizontal flow directed transverse to the imposed magnetic field. The transition to 3D dynamics is preceded by a series of 2D transitions in which the number of convection rolls decreases as Ra is increased. For sufficiently large Q, there is an eventual transition to two rolls just prior to the 2D-3D transition. The 2D-3D transition occurs when inertial forces become comparable to the Lorentz force, i.e., when Q/Re=O(1); 2D, magnetically constrained states persist when Q/Re≳O(1). Within the 2D regime, we find heat and momentum transport scalings that are consistent with the hydrodynamic asymptotic predictions of Chini and Cox [Phys. Fluids 21, 083603 (2009)1070-663110.1063/1.3210777]: the Nusselt number (Nu) and Reynolds number (Re) scale as Nu∼Ra1/3 and Re∼Ra2/3, respectively. For Q=106, we find that the scaling behavior of Nu and Re breaks down at large values of Ra due to a sequence of bifurcations and the eventual manifestation of mean flows.
Inertial particles distribute in turbulence as Poissonian points with random intensity inducing clustering and supervoiding
Schmidt, Lukas; Fouxon, Itzhak; Holzner, Markus (2017)
Physical Review Fluids
Inhomogeneous growth of fluctuations of concentration of inertial particles in channel turbulence
Fouxon, Itzhak; Schmidt, Lukas; Ditlevsen, Peter; et al. (2018)
Physical Review Fluids
Learning in two dimensions and controlling in three: Generalizable drag reduction strategies for flows past circular cylinders through deep reinforcement learning
Chatzimanolakis, Michail; Weber, Pascal; Koumoutsakos, Petros (2024)
Physical Review Fluids
We investigate drag reduction mechanisms in flows past two- and three-dimensional cylinders controlled by surface actuators using deep reinforcement learning. We investigate 2D and 3D flows at Reynolds numbers up to 8000 and 4000, respectively. The learning agents are trained in planar flows at various Reynolds numbers, with constraints on the available actuation energy. The discovered actuation policies exhibit intriguing generalization capabilities, enabling open-loop control even for Reynolds numbers beyond their training range. Remarkably, the discovered two-dimensional controls, inducing delayed separation, are transferable to three-dimensional cylinder flows. We examine the trade-offs between drag reduction and energy input while discussing the associated mechanisms. The present paper demonstrates discovery of transferable and interpretable control strategies for bluff body flows through deep reinforcement learning with limited computational cost.
Mechanisms of anomalous dispersion in flow through heterogeneous porous media
Tyukhova, Alina; Dentz, Marco; Kinzelbach, Wolfgang; et al. (2016)
Physical Review Fluids

Publications 1 - 10 of 54

Journal: Physical Review Fluids

Abbreviation

Publisher

Journal Volumes

ISSN

Description

Filters

Search Results