Multi-Fluid VoF model assessment to simulate the horizontal air–water intermittent flow

Akhlaghi, Mitra; Mohammadi, V.; Nouri, Mahtab; Taherkhani, Morteza; Karimi, Mehdi

doi:10.1016/j.cherd.2019.09.031

Cited by 57 publications

(20 citation statements)

References 29 publications

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“…The Multi-Fluid VOF [14] model is provided for coupling the Eulerian and the VOF models, and has been proved to be successful in the simulation of some complex multiphase flow fields in recent years. [15,16] Similarly to the reported cases, the benefits of the Multi-Fluid VOF model are also noticed in this simulation. It is confirmed that both the continuity of bubble plume and the interface characteristics, which are well described by the Eulerian model and the VOF model, respectively, are balanced in the Multi-Fluid VOF model.…”

Section: Introductionsupporting

confidence: 77%

CFD Modeling of Multiphase Flow in an SKS Furnace: The Effect of Tuyere Arrangements

Song

Jokilaakso

2021

Metall Mater Trans B

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The emerging bottom blown copper smelting (SKS) technology has attracted growing interest since it came into production. To further reveal the agitation behavior inside the bath and optimize the variable parameters, CFD simulation was conducted on a scaled down SKS furnace model with different tuyere arrangements. The Multi-Fluid VOF model was used for the first time in SKS furnace simulation and the simulated results show good agreement with an experimental water model reported in the literature, in terms of plume shape and surface wave. It was found that a low velocity region would appear on the opposite side of the bubble plume and persisted for a long time. To enhance the agitation in the low velocity region and reduce the dead zone area, an arrangement with tuyeres installed at each side of the furnace was recommended. Results suggested that a smaller tuyere angle difference would help to strengthen the agitation in the system. However, further investigation indicated that the difference in tuyere angle between two rows of tuyeres should be limited within a certain range to balance the requirements of higher agitation efficiency and longer lining refractory lifespan.

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Section: Introductionsupporting

confidence: 77%

CFD Modeling of Multiphase Flow in an SKS Furnace: The Effect of Tuyere Arrangements

Song

Jokilaakso

2021

Metall Mater Trans B

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“…Since the simulations were mainly devoted to investigate the inner flow field, which is helpful to evaluate the promotion of spiral agitation on hydrate nucleation and growth, we excluded hydrate formation in the simulations, which are difficult to be involved because of the phase change and multiphase flow systems. The method of volume of fluid (VOF) was used, 36,37 where the phase interface was tracked by solving the continuity equation of a fraction function, α (0 ≤ α ≤ 1). In the simulations, the non‐Newtonian flow after hydrate formation 38–40 was ignored, so both of the gas and liquid phases were regarded as Newtonian, immiscible, incompressible, and isothermal, and the continuity and momentum equations for the two‐phase flow were given by Equations () and (), respectively,

\nabla \cdot ((), \overset{true\to}{u}) = 0

\frac{\partial ((), ρ \overset{u}{true})}{\partial t} + \nabla \cdot ((), ρ \overset{u}{true} \overset{u}{true}) = - \nabla p + \nabla \cdot ([], μ ((), \nabla \overset{u}{true} + \nabla {\overset{true\to}{u}}^{T})) + ρ \overset{g}{true} + {\overset{true\to}{F}}_{s}

where

\overset{u}{true}

is the velocity vector (in m/s); ρ is fluid density (in kg/m 3 ); μ is fluid viscosity (Pa·s); p is pressure (in Pa); and

{\overset{true\to}{F}}_{s}

is the surface tension (in N), which can be calculated using Equation (),

{\overset{true\to}{F}}_{s} = σ \nabla \cdot ((), \frac{\nabla α}{(||, \nabla α)}) \nabla α

where σ is the surface tension coefficient (in N/m).…”

Section: Methodsmentioning

confidence: 99%

Methane hydrate production using a novel spiral‐agitated reactor: Promotion of hydrate formation kinetics

2021

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To enhance hydrate formation kinetics, we presented a novel spiral‐agitated reactor, where hydrates were synthetized in pure water systems, and fast hydrate kinetics was observed under extremely mild conditions. Hydrates can nucleate within 4 min under 3.5 MPa and 275.15 K at a rotating speed of 60 rpm, and large water‐to‐hydrate conversion (>85%) was obtained at a moderate condition of 4.85 MPa, 275.15 K, and 30 rpm with an average methane uptake of 139.78 V/V, demonstrating that pure water systems are feasible for hydrate‐based solidified natural gas (SNG) technology. Numerical simulations of flow fields inner the reactor were carried out, and four mechanisms behind the excellent promotion were proposed, dual‐agitation, two‐way convection, interfacial impact and micro bubbles, which significantly improve mass transfer, giving rise to fast hydrate nucleation and growth kinetics. These findings suggest extraordinary performance of spiral agitation, and this may pave way on the industrial application of hydrate‐based SNG technology.

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“…For the multi-phase flow model, the VOF model can be used for the system where air and water cannot be integrated with each other. In this paper, the VOF model simulated the gas-liquid two-phase flow [30][31][32]. The coordinate origin of the geometric model was located in the center of the intersection of the nozzle and the ejector tube, with the exit direction of the ejector tube as the positive x direction.…”

Section: Numerical Model Model Establishmentmentioning

confidence: 99%

Effect of Closure Characteristics of Annular Jet Mixed Zone on Inspiratory Performance and Bubble System

Wang

et al. 2021

Processes

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In the flotation process, gas-liquid properties and the bubble system greatly influence bubble mineralization. In order to clarify how the mechanism applies to the closure characteristics of an annular jet mixed flow zone on the inspiratory performance and the bubble system, different degrees of closure on the velocity field and gas-liquid ratio in the mixed flow zone were investigated using numerical simulation. The variations in the characteristics of bubble size distribution, rising velocity, and gas content under different closure levels were measured with a high-speed dynamic camera technology. The results confirmed that when the closure degrees of the mixed flow zone improved, the inlet jet could gradually overcome the static pressure outside the nozzle effectively. It formed a gas-liquid mixing zone with high turbulence first, and a large pressure difference at the gas-liquid junction second. This helped to increase the inspiratory capacity. At the same time, the gas-liquid ratio rose gradually under conditions of constant flow. When the nozzle outlet was completely closed, the gas-liquid ratio gradually stabilized. For the bubble distribution system, an enhancement in the closure degrees can effectively reduce the bubble size, and subsequently, the bubble size distribution became more uniform. Due to the improved gas-liquid shear mixing, the aspect ratio of the bubbles can be effectively changed, consequently reducing the bubble rising speed and increasing the gas content and bubble surface area flux of the liquid.

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Multi-Fluid VoF model assessment to simulate the horizontal air–water intermittent flow

Cited by 57 publications

References 29 publications

CFD Modeling of Multiphase Flow in an SKS Furnace: The Effect of Tuyere Arrangements

CFD Modeling of Multiphase Flow in an SKS Furnace: The Effect of Tuyere Arrangements

Methane hydrate production using a novel spiral‐agitated reactor: Promotion of hydrate formation kinetics

Effect of Closure Characteristics of Annular Jet Mixed Zone on Inspiratory Performance and Bubble System

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