Article
Engineering, Chemical
Zhanghao Wan, Shiliang Yang, Duzuo Tang, Haibin Yuan, Jianhang Hu, Hua Wang
Summary: The gas-solid swirling flow characteristics of coaxial jets in an industrial-scale annular pipe with a helical swirler are numerically simulated using CFD-DEM. The validated numerical model is used to discuss the general flow pattern of coaxial jets, gas-particle mixing behavior, and particle-scale information. The effect of the swirler's geometry parameters on particle azimuthal velocity and particle Reynolds number is analyzed. The results show that the swirler enhances turbulent disturbance and gas vorticity, and increasing the vane angle and diameter of the swirler is beneficial for particle dispersion.
Article
Chemistry, Physical
Palash S. Sarate, Tejas G. Murthy, Prerna Sharma
Summary: The study investigates the influence of the repose angle, a key geometric property, on granular flows, revealing significant differences in the repose angle characteristics between long flexible granular chains and spherical particles. It is found that the stability of granular chains is affected by the aspect ratio of the pre-filled column, with granular chains below a critical aspect ratio ceasing flow and stabilizing into columns.
Article
Thermodynamics
A. Mitra, S. Murugan, R. van Hout, A. Kleiman, M. Raizner, B. Cukurel
Summary: This study presents detailed planar PIV measurements of the flow field in the near-field of a free coaxial air jet. The measurements were conducted at different outer to inner jet velocity ratios while keeping the inner jet velocity constant. The results show that the nozzle geometry and flow exit conditions have a significant impact on the vortex generation frequency, and the outer and inner jet are strongly coupled for the present nozzle geometry and jet exit flow conditions.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2023)
Article
Chemistry, Applied
Marcelo Dal Belo Takehara, Angel David Garcia Llamas, Muhammad Aqib Chishty, Kentaro Umeki, Rikard Gebart
Summary: Enhanced particle dispersion during biomass gasification has been found to significantly affect soot emission, leading to improved efficiency and reliability of entrained flow reactors (EFRs). Factors such as Strouhal number, pressure amplitude, swirl number, and center jet velocity were investigated for their influence on particle dispersion, with stronger effects observed for higher forcing amplitudes and swirl numbers, especially at lower Stokes numbers.
FUEL PROCESSING TECHNOLOGY
(2022)
Article
Materials Science, Multidisciplinary
X. Tang, J. Yang
Summary: This study presents a novel grain-scale model to investigate the effect of particle morphology on elastic wave propagation in granular materials. The results show that increasing particle aspect ratio leads to a notable rise in elastic wave velocity, while increased particle blockiness causes a moderate reduction in velocity. Furthermore, particles with higher aspect ratio have a broader range of transmitted frequencies compared to those with greater blockiness.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2021)
Article
Thermodynamics
Yang Liu, Jiatong Liu, Guohui Li, Lixing Zhou
Summary: A novel particle subgrid scale model is established to simulate the effect of gas flow on particle motion behaviors, and a four-way coupling method is developed to describe particle-particle collisions. The simulation results of the multiphase swirling flow in a coaxial chamber show good agreement with experimental measurements, capturing the evolution of coherent structures, recirculation, periodic vortices formation, and mixing. The radial spread of particle dispersions and momentum exchanges contribute to the stabilization of flame in comparison to gas-annular flow. The core-annular flow structures and normal distribution of instantaneous particle velocity are observed. The axial-tangential gas and particle fluctuation velocities are significantly higher at the shear layers of the core-jetting regions. ©2023 Elsevier Ltd. All rights reserved.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Engineering, Chemical
Hongfa Sun, Liang Huang, Jibo Long, Fang Ruan
Summary: In this paper, a physical model of particle flow impacting the wall at different angles is established, and the wear condition of the particle-wall impact is studied using CFDDEM coupling method. The effects of particle incidence angle, velocity, and volume fraction on wall wear are analyzed. The results show that the particle incidence angle between 15 and 30 degrees results in the largest mass loss and erosion ratio on the target plate. The increase in particle impact velocity leads to an exponential increase in mass loss, erosion ratio, and wear depth, while the particle volume fraction is positively correlated with the mass loss of the target plate and affects the wall wear morphology.
Article
Mechanics
Xiaoling Shi, Dunlan Song, Hui Tian, As'ad Alizadeh, Masood Ashraf Ali, Mahmoud Shamsborhan
Summary: Comprehensive computational investigations have been conducted to examine the role of an annular air jet on fuel mixing in the combustion chamber. The results show that the injection of the annular jet can enhance circulations and improve fuel mixing inside the chamber.
Article
Optics
Mattia Contino, Gerardo Paolillo, Carlo Salvatore Greco, Tommaso Astarita, Gennaro Cardone
Summary: This paper presents the application of laser-based three-dimensional velocimetry techniques in the analysis of submerged impinging swirling jets, focusing on the effects of the swirl number on the formation and development of coherent vortex structures in this flow. The study also includes simultaneous velocity and temperature measurements to elucidate the role of vortex structures in flow dynamics and energy transport.
OPTICS AND LASERS IN ENGINEERING
(2022)
Article
Thermodynamics
Tej Pratap Singh, Anupam Dewan
Summary: This computational study investigates the enhancement of heat transfer using different wall-bounded jets, specifically focusing on the effect of the amplitude of the wavy surface and offset ratio. The results show that the shear-stress transport k-omega model provides good agreement with experimental results. The heat transfer enhancement and thermal-hydraulic performance increase with the amplitude of the sinusoidal wall.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Chemistry, Physical
Mohd Ilyas Bhat, Prerna Sharma, T. G. Sitharam, Tejas G. Murthy
Summary: This study investigates the mechanics of standing columns formed during the repose of flexible granular chains. By simulating experiments and evaluating various parameters, it is found that the links connecting the particles provide lateral stability to the column, enabling it to stand. In addition, a self-confining radial stress near the base of the column generated by the rearrangement of contact forces also plays an important role.
Article
Chemistry, Multidisciplinary
Pengqiang Yu, Yang Liu, Muke Shi, Zixuan Chen
Summary: The purpose of this study is to develop a micromechanical-based microstructure model for transversely isotropic granular media and investigate the propagation characteristics of particle rotation waves. The researchers introduced relative deformation tensors to describe local deformational fluctuation and derived the constitutive relations based on micro-macro deformation energy conservation. The study analyzed the dispersion characteristics and bandgap features of particle rotation waves and found that the microstructure model accurately predicted the waves and had a significant impact on their dispersion relations and bandgap widths.
APPLIED SCIENCES-BASEL
(2022)
Article
Mechanics
Marco Atzori, Sergio Chibbaro, Christophe Duwig, Luca Brandt
Summary: This paper evaluates the performances of three stochastic models for particle dispersion in three-dimensional turbulent flow. The continuous Lagrangian stochastic model shows better agreement with the large-eddy simulations compared to the discrete stochastic models, especially for particles with higher inertia.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2022)
Article
Environmental Sciences
Huang Bo-lin, Li Bin, Zheng Jia-hao, Feng Wang-li, Chen Xiao-ting, Luo Chao-lin
Summary: This study used particle imaging velocimetry (PIV) to examine impulse waves generated by the collapse of pillar-shaped rock masses in Three Gorges, China, and found that an increase in the aspect ratio of the pillar and water depth would decrease the potential energy of the granular pillar and reduce the efficiency of energy conversion to the liquid phase.
JOURNAL OF MOUNTAIN SCIENCE
(2022)
Article
Engineering, Chemical
V. Marzulli, C. S. Sandeep, K. Senetakis, F. Cafaro, T. Poeschel
Summary: The study investigated the frictional properties and mechanical behavior of two different types of sands under different conditions, finding higher macroscopic friction angles for lunar regolith simulant and smaller strength decay for Ottawa sand in direct shear tests. The study also revealed similar strength envelopes for both materials under wet and dry conditions, with higher inter-particle friction for the lunar simulant in wet conditions. Additionally, the differences between bulk and inter-particle friction for the lunar simulant were emphasized in dry conditions, with water having a noticeable effect on the friction coefficient only at the micro-scale.
Article
Mechanics
Nicolas Bouvet, Savannah S. Wessies, Eric D. Link, Stephen A. Fink
Summary: This study presents a framework to characterize firebrand flows and compare exposure through the use of a measurement device and data processing methods. The ability to perform exposure comparisons and recognize combustion states is demonstrated.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
P. Botticini, G. Lavalle, D. Picchi, P. Poesio
Summary: This study investigates the gravity-driven liquid layer problem on an inclined plate, taking into account the variable density of the fluid. The study examines the influence of density variation on the formulation of a depth-averaged model and the role of compressibility in long-wave interfacial instability.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Jean-Paul Caltagirone
Summary: This article introduces a method for modeling capillary flows on a surface or at the interface of two fluids. The method involves handling the two components of capillary acceleration using the divergence and curl of surface normal. The proposed formulation is characterized by directional curvature based on dihedral angle, intrinsic anisotropic surface tension per unit mass, and introduction of capillary potential.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Qi-Teng Zheng, Chun-Bai-Xue Yang, Shi-Jin Feng, Yu-Chen Song, Yong Zhao, Yu-Lin Wu
Summary: This paper proposes a new two-phase partitioning boundary model to accurately predict the drying process of a porous medium from saturated to unsaturated conditions. The model is validated through laboratory soil drying tests and the study also investigates the effects of air-water interfacial area and water retention parameters on the drying process.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Alexandra Metallinou Log, Morten Hammer, Svend Tollak Munkejord
Summary: Flashing flow is commonly found in industrial systems and accurate flashing models are essential for the design of safe and efficient CO2 transportation systems. We propose a homogeneous flashing model that takes into account the physical phenomena of phase change. The model is fitted using CO2 pipe depressurization data and we find that the same model parameters can be applied for different cases.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Q. Tan, S. A. Hosseini, A. Seidel-Morgenstern, D. Thevenin, H. Lorenz
Summary: The possible impact of temperature differences during crystal growth is investigated in this study. A numerical model is developed to simulate the crystallization dynamics of (S)-mandelic acid, taking into account temperature effects. The study shows that the heat generation at the crystal interface has only a small effect on the surrounding temperature field.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Hideki Murakawa, Sana Maeda, Sven Eckert
Summary: This study investigates the behavior of bubbles in a liquid metal under the influence of a magnetic field, particularly bubble chains. The results show that increasing the magnetic field strength suppresses the oscillations of the bubbles and concentrates their crossing positions in a specific area. Applying these findings to numerical models can further optimize continuous casting processes.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Johanna Potyka, Kathrin Schulte
Summary: This paper presents an advanced Volume of Fluid (VOF) method for performing three-dimensional Direct Numerical Simulations (DNS) of the interaction of two immiscible fluids in a gaseous environment with large topology changes. The method includes efficient reconstruction of phase boundaries near the triple line using a Piecewise Linear Interface Calculation (PLIC) method and enhanced surface force modeling with the Continuous Surface Stress (CSS) model. Implementation of these methods in the multi-phase flow solver Free Surface 3D (FS3D) yielded successful validation. The simulations provide valuable insights into the collision process and can support future modeling of immiscible liquid interaction.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Martin Rohde, Sebastian Burgmann, Uwe Janoske
Summary: This study investigates the effect of superimposing an incident flow and two-dimensional vibration on the critical air flow velocity required for the detachment of a droplet. The results show that oscillatory excitation at specific frequencies can significantly reduce the critical velocity for droplet detachment.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Tea-Woo Kim, Baehyun Min
Summary: Liquid-gas two-phase slug flow is a complex flow pattern in energy systems, and accurately predicting slug liquid holdup is crucial for system design and operation. Existing HLLS models have limited applicability due to a lack of physical basis. This study proposes a new dimensionless number SP and correlates it with HLLS data, resulting in a unified HLLS correlation that agrees closely with experimental data.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Christian Lieber, Stephan Autenrieth, Kai-Yannic Schoenewolf, Amy Lebanoff, Rainer Koch, Sterling Smith, Paul Schlinger, Hans-Joerg Bauer
Summary: The observation of acoustically levitated droplets offers great potential for studying their evaporation characteristics. The main objective of this study is to present an experimental setup that minimizes the disturbing effects of the levitation technique in order to investigate convective heat and mass transfer during droplet evaporation.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Facundo Cabrera-Booman, Nicolas Plihon, Mickael Bourgoin
Summary: The settling behavior of individual spheres in a quiescent fluid was experimentally studied. The mean trajectory angle with the vertical showed complex behavior as the parameters Gamma and Ga varied. The transition from planar to non-planar trajectories and the emergence of semi-helical trajectories were observed, especially for denser spheres.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Hongbin Wang, Hanwen Luo, Jinbiao Xiong
Summary: This article introduces an iterative screening method for closure models in nucleate boiling flow simulation, and demonstrates its accuracy through experiments.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Alexandra Metallinou Log, Morten Hammer, Han Deng, Anders Austegard, Armin Hafner, Svend Tollak Munkejord
Summary: This study investigates the rapid depressurization of liquid CO2 and compares the predictions of different models. It is found that higher temperatures result in shorter relaxation times.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Rizwan Zahoor, Sasa Bajt, Bozidar Sarler
Summary: This numerical study evaluates the jet characteristics of non-Newtonian power-law fluids in a gas dynamic virtual nozzle. The results show that shear-thinning fluids result in thicker, longer, and slower jets compared to shear-thickening fluids. Additionally, a dripping-jetting phase diagram of the nozzle is obtained by varying the power law index, gas, and liquid flow rates.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
