Article
Engineering, Civil
Prateek Kumar Singh, Xiaonan Tang, Yutong Guan, Hamidreza Rahimi
Summary: A new model is proposed in this paper to calculate the percentage shear force carried by floodplains, which is simple and accurate and suitable for a wide range of applications.
JOURNAL OF HYDROLOGY
(2022)
Article
Mechanics
M. Vernet, M. Pereira, S. Fauve, C. Gissinger
Summary: An experiment was conducted to study the flow of an electrically conducting fluid in a thin disc under the influence of an azimuthal Lorentz force. Different flow patterns were observed, including quasi-Keplerian velocity profiles, turbulent flow with large fluctuations and a Keplerian mean rotation profile, and a quasi-bidimensional turbulent flow with the formation of large scale condensates in the horizontal plane. These results are attributed to the instability of the Bodewadt-Hartmann layers at large Reynolds numbers and are discussed within the context of similar astrophysical turbulent flows.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Zehao Li, Zhigang Zuo, Zhongdong Qian
Summary: In this study, the characteristics of hydrodynamic cavitation bubbles generated from a crevice in near-wall shear flows were experimentally and theoretically investigated. The frequency of the bubbling was found to be highly sensitive to the content of non-condensable gas. Based on the experimental observations, a physical process of periodic bubbling was summarized and a theoretical explanation for the observed cavitation threshold and frequency was provided.
Article
Mechanics
Pierre Ricco, Martin Skote
Summary: The study shows that the Fukagata et al.’s identity simplifies to the von Kaman momentum integral equation for free-stream boundary layers. It is found that the influence of Reynolds stresses on wall-shear stress cannot be quantified for free-stream boundary layers. Analogous identities are found for channel flows, where the laminar and turbulent contributions to the skin-friction coefficient are distinguished. The study also decomposes the skin-friction coefficient into integral thicknesses to quantify the contributions of different terms of the streamwise momentum equation to friction drag.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Golsa Tabe Jamaat, Yuji Hattori
Summary: In this study, the ability of a convolutional neural network (CNN) for wall-modeling in large eddy simulation is assessed through a priori evaluation. The CNN is trained using data from direct numerical simulation (DNS) of turbulent channel flow. The performance of the CNN-based wall models is compared using input data from different regions of the flow, and the models are tested under various conditions. The results show that the CNN wall models using data from the inner layer have better accuracy in establishing a wall model compared to those using input data from the logarithmic layer.
Article
Mechanics
Yanchong Duan, Qiang Zhon, Guiquan Wan, Qigang Chen, Fujun Wan, Danxun Li
Summary: This paper reports a new phenomenon in open channel flows, where higher population densities of spanwise vortices are observed near the free surface compared to turbulent boundary layers. Additional retrograde spanwise vortices are present in OCFs beyond y/h > 0.2, prompting a re-examination of the wall-normal extent of the free-surface effect. Possible mechanisms for this phenomenon are also provided.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Multidisciplinary
Gabriel Cuomo, Zohar Komargodski, Avia Raviv-Moshe
Summary: This article investigates line defects in conformal field theories and reveals that the flow on these defects is irreversible, accompanied by a decreasing entropy function. The generalization of the g theorem to line defects in arbitrary dimensions is demonstrated through a flow between Wilson loops in four dimensions.
PHYSICAL REVIEW LETTERS
(2022)
Article
Mechanics
Jie Yao, Xi Chen, Fazle Hussain
Summary: Well-resolved direct numerical simulations of turbulent open channel flows were performed, and it was found that the flow behavior in the near-wall region is similar to closed channel flows, but differs notably in the outer region. The free surface in open channel flows plays a crucial role in various flow phenomena.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Computer Science, Interdisciplinary Applications
Marin Lauber, Gabriel D. Weymouth, Georges Limbert
Summary: Immersed boundary methods are widely used for simulating interactions between dynamic solid objects and fluids due to their computational efficiency and modeling flexibility. However, thin geometries often violate the boundary conditions in existing immersed boundary projection algorithms. This study proposes a minimal thickness modification for the Boundary Data Immersion Method (BDIM-sigma) to address this issue and improve the accuracy of high-speed immersed surface simulations.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Thermodynamics
Junil Ryu, Junkyu Kim, Jonghyeok Park, Hyoungsoo Kim
Summary: The study demonstrates that the internal flow pattern inside a sessile droplet can be controlled by adjusting the position and number of volatile liquid sources. The theoretical model based on Stokes flow predicts the primary flow structures of the experimental results. The main conditions determining the internal flow include the distribution of vapor molecules and surface tension values depending on the concentration of the volatile liquid.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Engineering, Marine
Guoqing Jin, Zhe Sun, Zhi Zong, Li Zou, Yingjie Hu
Summary: A novel technique utilizing conformal mapping and the circle theorem has been developed to address the boundary penetration issue in 2D discrete vortex simulations. The technique introduces an identical vortex blob outside the body to prevent circulation loss caused by penetration into the body, maintaining constant circulation and streamlined body surfaces. Validation studies and comparisons with experimental data confirm the effectiveness of the approach.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2021)
Article
Mechanics
Sida He, Han Liu, Lian Shen
Summary: Large-eddy simulation is used to investigate the dynamics and energy transfer in turbulent canopy flows. An immersed boundary method and a beam model are employed to capture the dynamics of individual stems. The results show that the waving term associated with the canopy drag-flow velocity correlation can be as large as the shear production term near the canopy top. Spectral energy budget analyses reveal the dominant effects of coherent structures and intervals between adjacent stems.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Yanchong Duan, Qiang Zhong, Guiquan Wang, Peng Zhang, Danxun Li
Summary: This study investigates the contributions of different scale motions to the mean wall-shear stress in smooth-walled open channel flows, revealing the significant impact of large-scale and very-large-scale motions on the wall-shear stress. Comparisons with closed channel flows show slightly higher and lower contributions in specific wavelength ranges in open channel flows, indicating the important role of free-surface effects in open channel flows. Potential mechanisms are discussed to support the observed differences between the two types of flows.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mathematics
Alexander Dunlap, Yu Gu
Summary: This article discusses a particle undergoing Brownian motion in Euclidean space of any dimension, forced by a Gaussian random velocity field that is white in time and smooth in space. The study shows that, conditional on the velocity field, the quenched density of the particle after a long time can be approximated pointwise by the product of a deterministic Gaussian density and a spacetime-stationary random field U.
JOURNAL OF FUNCTIONAL ANALYSIS
(2022)
Article
Mathematics, Applied
Evgenii S. Baranovskii
Summary: This paper presents a novel mathematical model describing the steady-state 3D flows of a non-Newtonian fluid in a pipe network. The approach rejects velocity field averaging and applies conjugation conditions for mass balance at interior network junctions. The main result is an existence theorem for weak solutions with large data, proved using the Galerkin procedure, topological degree theory, monotone operator techniques, and compactness arguments.
MATHEMATICAL METHODS IN THE APPLIED SCIENCES
(2021)
Article
Mechanics
K. Lippera, M. Morozov, M. Benzaquen, S. Michelin
JOURNAL OF FLUID MECHANICS
(2020)
Article
Physics, Applied
Joshua Giltinan, Panayiota Katsamba, Wendong Wang, Eric Lauga, Metin Sitti
APPLIED PHYSICS LETTERS
(2020)
Article
Multidisciplinary Sciences
Hanumantha Rao Vutukuri, Maciej Lisicki, Eric Lauga, Jan Vermant
NATURE COMMUNICATIONS
(2020)
Article
Multidisciplinary Sciences
Maria Tatulea-Codrean, Eric Lauga
SCIENTIFIC REPORTS
(2020)
Article
Multidisciplinary Sciences
Albane Thery, Lucas Le Nagard, Jean-Christophe Ono-dit-Biot, Cecile Fradin, Kari Dalnoki-Veress, Eric Lauga
SCIENTIFIC REPORTS
(2020)
Article
Physics, Fluids & Plasmas
Alexander Chamolly, Eric Lauga
PHYSICAL REVIEW FLUIDS
(2020)
Article
Chemistry, Physical
Akash Choudhary, K. V. S. Chaithanya, Sebastien Michelin, S. Pushpavanam
Summary: This study examines the motion of chemically active Janus particles in weak confinement, investigating the effects of confining planar boundaries on phoretic and hydrodynamic interactions. New states such as channel-spanning oscillations and damped oscillations around the centerline were identified, expanding on previous analyses of single wall interactions. Insights also suggest that biological and artificial swimmers sense their surroundings through long-ranged interactions that can be altered by changing surface properties.
EUROPEAN PHYSICAL JOURNAL E
(2021)
Article
Mechanics
Francisco Rojas-Perez, Blaise Delmotte, Sebastien Michelin
Summary: The study demonstrates that chemically active colloids can self-propel by modifying the concentration of chemical solutes surrounding them, which generates chemical gradients and hydrodynamic flows that alter the trajectories of other particles. Therefore, the dynamics of suspensions with reactive particles is fundamentally governed by hydro-chemical interactions, posing challenges for solving detailed hydro-chemical problems with many particles. Most current methods rely on Green's functions of Laplace and Stokes operators to approximate particle behavior in the far field, which is only valid in very dilute conditions and simple geometries.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Francesco Picella, Sebastien Michelin
Summary: This study investigates the self-propulsion of isotropic colloids inside capillary tubes through numerical simulations. The results demonstrate that spatial confinement promotes the colloids' spontaneous motion and significantly affects the self-propulsion velocities.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Physics, Fluids & Plasmas
Nikhil Desai, Sebastien Michelin
Summary: Active droplets can swim in viscous flows due to convective transport of a chemical solute produced at their surface, with stability against nonaxisymmetric perturbations and emergence of self-propulsion along the wall. Reduction in the drop-wall separation destabilizes modes and promotes self-propulsion due to confinement-induced localization of chemical gradients. Quadrupolar states are more unstable than dipolar counterparts favoring stronger slip forcing on the drop surface.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Mechanics
T. Traverso, S. Michelin
Summary: By studying autochemotactic Janus particles, this research reveals the effects of flow and chemical induction, as well as the influence of confinement, on collective behavior.
JOURNAL OF FLUID MECHANICS
(2022)
Review
Mechanics
Sebastien Michelin
Summary: Microscopic active droplets swim autonomously in viscous flows by exploiting solute transport and self-generated Marangoni flows. They are of great interest to physicists, chemists, biologists, and fluid dynamicists for analyzing self-propulsion and collective dynamics, developing cellular models, or performing biomedical and engineering applications. This review focuses on the recent developments of these fascinating droplets, including mathematical and physical modeling, experimental design, and characterization.
ANNUAL REVIEW OF FLUID MECHANICS
(2023)
Article
Physics, Fluids & Plasmas
Nikhil Desai, Sebastien Michelin
Summary: Active drops emit/absorb chemical solutes, creating concentration gradients and driving their own transport and propulsion. Despite their isotropy, active drops can achieve directed self-propulsion as long as the Peclet number is larger than a critical threshold. This study investigates the spontaneous motion and nonlinear saturation of an isotropic phoretic colloid confined along a rigid wall, revealing that reducing the particle-wall separation enhances the swimming speed through efficient rearrangement of solute concentration gradients.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Chemistry, Physical
Kevin Lippera, Michael Benzaquen, Sebastien Michelin
Summary: For symmetric collisions, a systematic alignment of droplets' trajectories is observed, while for more generic collisions, complex and diverse dynamical regimes are observed, resulting in significant scattering.
Article
Chemistry, Physical
Sebastien Michelin, Simon Game, Eric Lauga, Eric Keaveny, Demetrios Papageorgiou
