Effect of Stefan flow on the drag force in flow past random arrays of spheres

Chen, Xihao; Du, Shaohua; Li, Zhao; Yang, Bolun; Zhou, Qiang

doi:10.1016/j.cej.2021.128691

Cited by 17 publications

(8 citation statements)

References 44 publications

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“…The chemical equation for the formation of the crust is CaCO [41,42]. According to Stephenson's theory, a thin lm of water formed by condensation can hold more dust particles with polluting properties, such as sulphur dioxide, together [45,46]. The speed of dust concentration depends on the temperature difference between the wall and the air in contact with it.…”

Section: Discussionmentioning

confidence: 99%

Impacts of bomb explosions on weathering damage of architectural heritage

Wang,

Mol,

Tucker

et al. 2024

Preprint

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The effects of bomb impacts, including the explosive force and combustion associated with these impacts, are preserved in only a few cities across the UK. In particular, World War Two (WWII) has left scars across a wide range of structures as a result of air raids. On immovable heritage, such as architectural structures, these impacts commonly take the form of craters, fractures and fire damage to stonework. This instantaneous damage is subsequently exposed to environmental stresses, such as moisture cycling, thermal stress and the movement of soluble elements and can thus lead to further deterioration of the stone. In this study, RSH (Rock Surface Hardness) measurements, permeametry measurements and microscopic observations were selected to capture stone deterioration data from 80-year-old bomb impacts on two walls of the Labour Exchange in Bath (UK) for spatial distribution analysis (Kriging) in GIS (Geographic Information Systems). The results show that the weathering forms that were found on the two walls can be attributed to nine different types. They can provide quantitative assessment of damage caused by bomb explosions and combustion in the war. The increase in permeability of walls and craters is shown to be primarily caused by the bomb explosion and combustion, whereas the decrease of hardness is associated with subsequent stone deterioration processes. This indicates that the interplay of initial damage likely accelerates subsequent response to environmental stress, extending the initial damage patterns from the impact crater to larger areas of stonework.

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Section: Discussionmentioning

confidence: 99%

Impacts of bomb explosions on weathering damage of architectural heritage

Wang,

Mol,

Tucker

et al. 2024

Preprint

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“…(7) (8) where represents the force between the moving obstacle and the wall, and represents the motion resistance of the moving obstacle to the pedestrian flow.…”

Section: Macroscopic Pedestrian Flow Model Based On Sphmentioning

confidence: 99%

“…The moving obstacle model is abstracted as a sphere [8], and the motion resistance force in the pedestrian flow is:…”

Section: Macroscopic Pedestrian Flow Model Based On Sphmentioning

confidence: 99%

Stability analysis based on a coupled macroscopic pedestrian flow model considering moving obstacles

Zhao

Li²,

Li³

et al. 2022

International Workshop on Automation, Control, and Communication Engineering (IWACCE 2022)

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In the high-density crowd flow places in public buildings, typical mobile obstacles, such as trolley cases, mobile sweeping trolleys, shuttle trolleys, police patrol cars, etc., carried by passengers bring convenience for passengers to travel, and can also act as typical obstacles that hinder the flow of people. It is easy to block the flow of people, cause the crowd to become unstable, and cause overcrowding and even stampede accidents. To study the influence of moving obstacles on crowd stability, this paper analyzes the spatial and moving characteristics of typical moving obstacles and constructs a motion model of moving obstacles. Furthermore, based on smooth particle hydrodynamics (SPH), a coupled macroscopic pedestrian flow model including moving obstacles and pedestrian flow is proposed. In order to verify the effectiveness of this proposed coupled motion model, this study takes trolley luggage as an example to design and implement a moving obstacle experiment in pedestrian flow, exploring the impact of moving obstacles to the pedestrian flow, further to study the stability of pedestrian flow.

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“…It can achieve superior efficiency and significantly reduce the pollutants generated in the traditional gasification and combustion process. , For the gas–solid reactive flows in the SCWG reactors, the surface material of coal or biomass particles is heated and gasified to form a mass flow that is perpendicular to the particle surface and reacts with the surrounding fluid. The mass exchange between particles and surrounding fluid is called Stefan flow, and the momentum, mass transfer, heat transfer, and chemical reactions between particles and fluid are coupled and affected by Stefan flow, making the particle–fluid–particle interactions more complicated. − The impact of Stefan flow on the gas–solid particle reacting flow is further reflected in hydrodynamic behavior and reaction efficiency. − In the reactor, the drag coefficient ( Cd ) and Nusselt number ( Nu ) are two crucial characteristics of particle force and heat transfer efficiency. , Pioneer scholars’ in-depth research and fitted valuable empirical formulas for inert particles in the cold environment can effectively guide industrial production. , However, the previous empirical formulas of the inert particles are no longer applicable for the reactive particles in the high-temperature and reactive environment, and a thorough analysis and complete understanding of the particle–SCW–particle interaction combined with the influence of the Stefan flow, such as heat transfer and flow characteristics, are urgently needed for the scale-up, design, and optimization of the reactor for industrial application.…”

Section: Introductionmentioning

confidence: 99%

Direct Numerical Simulation of Fluid Flow and Heat Transfer of a Reactive Particle Layer with Stefan Flow in Supercritical Water

Wang

Jin

2023

Ind. Eng. Chem. Res.

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Supercritical water gasification is an efficient and clean way of energy conversion. The research on different scales, such as the system, reactor, and particle, has different temporal and spatial significance. A study on particle−particle and particle− fluid−particle interaction on the particle scale has a fundamental guiding value for revealing gasification performance on the reactor scale. Reactive particles such as coal are pyrolyzed and gasified in a high-temperature and high-pressure reactor to form Stefan flow, which affects the mass, momentum, and energy transfer between particles and supercritical water. In this paper, a particle-resolved direct numerical simulation study of a reactive particle layer in supercritical water is carried out to investigate the effect of different particle layer solid holdups and Stefan flow intensities and distributions on the flow and heat transfer process between the particle layer and supercritical water. This work analyzes the pressure and friction drag coefficients to which the particles are subjected and specifies the flow, velocity, and temperature distribution inside and around the particle layer. The results show that the drag coefficient and Nusselt number of particles in the particle layer decrease gradually along the flow direction, and the presence of particle Stefan flow further reduces the drag force and Nusselt number of particles. With the increasing solid holdup of the particle layer, the particle−fluid−particle interaction becomes more intense, and the effect of Stefan flow cannot be negligible.

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Effect of Stefan flow on the drag force in flow past random arrays of spheres

Cited by 17 publications

References 44 publications

Impacts of bomb explosions on weathering damage of architectural heritage

Impacts of bomb explosions on weathering damage of architectural heritage

Stability analysis based on a coupled macroscopic pedestrian flow model considering moving obstacles

Direct Numerical Simulation of Fluid Flow and Heat Transfer of a Reactive Particle Layer with Stefan Flow in Supercritical Water

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