Article
Mechanics
Jie Zhang, Ming-Jiu Ni, Jacques Magnaudet
Summary: Highly resolved simulations were used to study the buoyancy-driven motion of two identical gas bubbles released in a liquid at rest. Two distinct evolutions were observed depending on the values of Galilei (Ga) and Bond (Bo) numbers, with the bubbles either moving in a side-by-side motion or with the trailing bubble drifting laterally. Bubble deformation played a key role in determining the system's evolution.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Alessio Innocenti, Alice Jaccod, Stephane Popinet, Sergio Chibbaro
Summary: The study investigates bubble-induced turbulence through numerical simulations, comparing results with experiments and previous simulations to assess the accuracy of the model. Analysis reveals that the energy transfer mechanisms and potential cascades are unveiled through a local scale-by-scale analysis in physical space.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Jie Zhang, Ming-Jiu Ni, Jacques Magnaudet
Summary: This study numerically investigates the dynamics of gas bubbles released in line under highly inertial conditions. Depending on the ratios of buoyancy, viscous and capillary forces, the bubbles can either rise independently or continue to interact and possibly collide. The shape of the bubbles and the initial distance between them play a crucial role in determining their trajectories.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Stephane Perrard, Alienor Riviere, Wouter Mostert, Luc Deike
Summary: In this study, the deformation modes and lifetime of a bubble in a turbulent flow are investigated through numerical simulations and theoretical analysis. Two temporal regimes are observed during the bubble deformation process, with the first regime driven by inertial forces and the second regime resulting from a balance between inertial forces and surface tension.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Daniel J. Ruth, Marlone Vernet, Stephane Perrard, Luc Deike
Summary: The study shows that the average rising speed of bubbles in liquid decreases with increasing turbulence intensity, following a specific proportional relationship. This is mainly due to the effects of nonlinear drag and the nearly isotropic behavior of the slip velocity on the mean rise speed.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Kazuki Maeda, Masanobu Date, Kazuyasu Sugiyama, Shu Takagi, Yoichiro Matsumoto
Summary: A series of experiments and modelling were conducted to study the interaction of a pair of spherical bubbles rising in a vertical channel. The results showed that bubbles take two preferential configurations depending on their mutual distance, which helps to elucidate the clustering mechanisms.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
D. Raciti, P. Brocca, A. Raudino, M. Corti
Summary: We present a new interferometric method to study the interactions between two gas bubbles in a liquid undergoing small-amplitude oscillations. The technique allows for accurate measurement of the amplitude, frequency, and phase of oscillation, as well as probing the interactions between the bubbles. This method is of great importance for understanding bubble interactions.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Alienor Riviere, Wouter Mostert, Stephane Perrard, Luc Deike
Summary: This study investigates the dynamics and statistics of bubble break-up in homogeneous and isotropic turbulence through direct numerical simulations, focusing on the influence of the Weber number on bubble break-up dynamics. The findings reveal that during the transition to stable conditions, bubble break-up occurs through both local and non-local production processes, resulting in a range of bubble sizes.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Mirko Gallo, Francesco Magaletti, Carlo Massimo Casciola
Summary: This study investigates the impact of solid walls on bubble formation in heterogeneous nucleation processes, exploring the direct effects of boundary conditions compliant with fluctuation-dissipation balance on nucleation.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Environmental
M. Gumulya, R. P. Utikar, V. K. Pareek, G. M. Evans, J. B. Joshi
Summary: 2D rectangular columns are often used for visualization and CFD studies of multiphase flows. In this study, a numerical analysis was conducted on the dynamics of a rising bubble within such a setup, indicating that the shape and motion of the bubble are influenced by the gap size and Reynolds number. Increasing Reynolds number results in a more elongated oblate spheroidal shape and predominantly rectilinear rise behavior of the bubble.
CHEMICAL ENGINEERING JOURNAL
(2021)
Article
Mechanics
Niklas Hidman, Henrik Stroem, Srdjan Sasic, Gaetano Sardina
Summary: This paper provides a comprehensive explanation for the lift force acting on a freely deformable bubble rising in a linear shear flow, and presents four distinct flow mechanisms and their associated vorticity dynamics. Theoretical framework and numerical simulations are used to support the explanations. The study also highlights the importance of considering the shear rate in modeling the lift force.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Engineering, Environmental
Kui Lai, Shiliang Yang, Hua Wang
Summary: Understanding the multi-scale characteristics of gas-liquid two-phase systems is crucial for enhancing reaction rates and resource and energy utilization efficiency in industrial processes. This study investigates the dynamics of bubble swarms and flow characteristics in gas-liquid two-phase systems using large eddy simulation and volume of fluid model. The results reveal different regions and behaviors during the bubble rising process, the effect of orifice number on bubble distribution and gas holdup, and the expansion of vortex structures and gas-liquid contact area with increasing orifice number. This research provides valuable insights for the design and optimization of gas-liquid two-phase systems in industrial applications.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Mechanics
Ebrahim Ghahramani, H. Strom, R. E. Bensow
Summary: Cavitating flows involve vapour structures with various length scales, highlighting the importance of accurately estimating small-scale cavities. A hybrid cavitation model that combines a mixture model with a Lagrangian bubble model has been developed to capture multi-scale dynamics and interactions between vapour structures and the continuous flow. This approach shows considerable improvements in predicting large cavities and capturing small-scale structures, even with lower mesh resolution.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Han Liu, Zuoli Xiao, Lian Shen
Summary: Ventilated cavitating flows are investigated using direct numerical simulations, providing a comprehensive description of the two-phase flow and the air leakage and vortex shedding processes. The mean velocity suggests the existence of three characteristic flow structures: shear layer, recirculating area, and jet layer. Turbulent kinetic energy is concentrated in the jet layer, with streamwise turbulent fluctuations dominating in both shear layer and jet layer. Air leakage and vortex shedding occur periodically and show a one-to-one correspondence, confirmed by velocity and volume fluid spectra results and the autocorrelation function. Coherent flow structures are analyzed using the spectral proper orthogonal decomposition method, identifying fine coherent structures associated with various instability and convection mechanisms. This study complements previous research by providing detailed descriptions of turbulent motions and complex interactions in cavitating flows.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Aditya Madabhushi, Krishnan Mahesh
Summary: We propose a compressible multi-scale model that captures the dynamics of both large vapour cavities and micro-bubbles and takes into account the compressibility of the medium. The model tracks the homogeneous mixture of liquid and resolved vapour in an Eulerian sense and tracks the unresolved vapour in a Lagrangian sense using a novel equation. The model has been validated and shown to accurately capture the collapse of single and multiple bubbles, as well as the interaction between bubbles in a cluster.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Xianyang Chen, Jiacai Lu, Gretar Tryggvason
Article
Energy & Fuels
Alireza Mahdavi Nejad, Gretar Tryggvason
JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME
(2020)
Article
Mechanics
Xuebo Zheng, Jiacai Lu, Bofeng Bai, Gretar Tryggvason
Article
Mechanics
Zaheer Ahmed, Daulet Izbassarov, Jiacai Lu, Gretar Tryggvason, Metin Muradoglu, Outi Tammisola
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2020)
Article
Computer Science, Interdisciplinary Applications
T. Arrufat, M. Crialesi-Esposito, D. Fuster, Y. Ling, L. Malan, S. Pal, R. Scardovelli, G. Tryggvason, S. Zaleski
Summary: The study focuses on the computation of flows with large density contrasts, using a discretization of the Navier-Stokes equation and considering the impact of capillary forces on incompressible flows. Mass and momentum advection is done in a consistent manner, incorporating the Volume-of-Fluid method and Height-Function method, along with different volume fraction advection methods.
COMPUTERS & FLUIDS
(2021)
Article
Computer Science, Interdisciplinary Applications
W. Aniszewski, T. Arrufat, M. Crialesi-Esposito, S. Dabiri, D. Fuster, Y. Ling, J. Lu, L. Malan, S. Pal, R. Scardovelli, G. Tryggvason, P. Yecko, S. Zaleski
Summary: Paris is a finite volume code specializing in simulations of immiscible multifluid or multiphase flows, based on the “one-fluid” formulation of the Navier-Stokes equations with interface tracking by Front-Tracking or Volume-of-Fluid method. It is written in Fortran, parallelized with MPI and domain decomposition.
COMPUTER PHYSICS COMMUNICATIONS
(2021)
Article
Mechanics
Xianyang Chen, Jiacai Lu, Gretar Tryggvason
Summary: This study examines a process for coarsening or filtering fully resolved numerical solutions for incompressible multiphase flows while retaining a sharp interface. Different phases are identified using an index function and small flow scales are embedded in other phases by solving diffusion equations with modified coefficients. This approach results in solutions similar to filtered fully resolved fields, particularly for the Rayleigh-Taylor instability at early times.
Article
Mechanics
Xianyang Chen, Jiacai Lu, Stephane Zaleski, Gretar Tryggvason
Summary: This article reports a study that uses skeletonization to describe complex liquid droplet structures. By diffusing an index function and moving the interfaces accordingly, the skeleton of the droplet can be obtained, representing its basic topology. Various quantitative measures are also explored to characterize and distinguish the skeleton structures of the droplets.
Article
Physics, Fluids & Plasmas
Xianyang Chen, Jiacai Lu, Gretar Tryggvason
Summary: This study uses machine learning to develop closure terms for a coarse grained model of two-dimensional turbulent flow directly from coarse grained data, accurately predicting the time evolution of the flow field.
Proceedings Paper
Mathematical & Computational Biology
Gretar Tryggvason, Jiacai Lu
INTERNATIONAL CONFERENCE ON NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2019
(2020)
Article
Nanoscience & Nanotechnology
Zhiping Yuan, Huimin Hou, Liyu Dai, Xiaomin Wu, Gretar Tryggvason
ACS APPLIED MATERIALS & INTERFACES
(2020)
Article
Mechanics
Wenbin Li, Jiacai Lu, Gretar Tryggvason, Ying Zhang
Summary: The self-transport of droplets on discontinuous wetting gradient surfaces is influenced by surface roughness, affecting both the transport velocity and stability of motion.