Sinking inside the box

Pritchard, David

doi:10.1017/jfm.2013.84

Cited by 5 publications

(5 citation statements)

References 11 publications

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“…In this model, the particle–gas interaction forces include the drag force ( F D ,i ) and pressure gradient force ( F Pg,i ). The drag force acting on the particles is calculated using the definition of the drag coefficient as given in eq 7, where the pressure gradient force is determined according to eq . where ρ g is the gas density, u g is the gas velocity, C D is the drag coefficient, A ′ is the projected particle area in the flow direction, u g – u p is the relative velocity between gas and particle, V p is the particle volume, and ∇ P is the local pressure gradient.…”

Section: Physical Model and Numerical Methodsmentioning

confidence: 99%

Modeling and Performance Analysis of Different Gas–Bioparticle Cyclone Separators: CFD–DEM Simulations

El-Emam,

Zhou,

Bai

et al. 2023

Ind. Eng. Chem. Res.

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This research presents a comprehensive study aimed at investigating the influence of different cyclone geometries on the flow field and performance in gas−bioparticle flows. Five distinct cyclone designs, including Stairmand high-efficiency (St 1 ), Stairmand high-flow (St 2 ), Swift high-efficiency (Sw 1 ), Swift highflow (Sw 2 ), and typical Lapple (TL), were involved. The investigation utilized a combination of computational fluid dynamics (CFD) and the discrete element method (DEM) to model the gas−particle behavior. The DEM accounted for the motion of individual particles using Newton's equations, while the CFD solved the Navier−Stokes equations to model the gas flow as a continuous medium. This numerical model successfully simulated the cyclone performance under three-dimensional (3D) true shape modeling of large-sized nonspherical bioparticles considering the particle−particle and particle−wall interaction forces. The experimental validation and verification of the model demonstrated an acceptable agreement with the simulated data. The findings revealed that cyclone dimensions significantly impacted both performance and particle behavior even when operating under identical conditions. Cyclones with matching dimensions between the bottom and vortex finder exhibited improved separation efficiency, while an increase in the vortex finder's diameter led to decreased efficiency, as in St 2 and Sw 2 cyclones. A comprehensive force analysis pinpointed regions of intense particle−wall collisions, predominantly at the cone wall apex and the wall opposite the cyclone inlet, particularly evident in St 1 , Sw 1 , and TL cyclones. Notably, particle−particle interaction forces played a crucial role in cyclone performance with increased separation efficiency observed due to particle collisions. The particle−gas forces, including drag and pressure gradient forces, were mainly affected in the inlet region and extended into the cylindrical part. The pressure gradient force exhibited a minimal impact on particle behavior. Among the cyclone designs tested, the Sw 1 cyclone demonstrated outstanding performance, achieving an impressive effectiveness of 94.4% under the given operational conditions. These findings provide a better understanding of the working mechanisms of gas−particle cyclones and similar swirling multiphase flow systems, allowing for improved optimization.

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Section: Physical Model and Numerical Methodsmentioning

confidence: 99%

Modeling and Performance Analysis of Different Gas–Bioparticle Cyclone Separators: CFD–DEM Simulations

El-Emam,

Zhou,

Bai

et al. 2023

Ind. Eng. Chem. Res.

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“…They solved their stability equations (28), (30), and (33) in the global t; z ð Þ domain. However, as mentioned by Ben et al, [20] Riaz et al, [3] and Pritchard, [21] the disturbances which are localized near the reaction front cannot be accurately captured in the t; z ð Þ domain, since the dominant operator, @ 2 =@z 2 does not have localized eigenfunctions that vanish at the semi-infinite boundary. Following their suggestion, we transform Equations (31) and (32) in a similar manner to the t; z ð Þ domain as follows: (18) and (20) for different values of…”

Section: Linear Stability Equationsmentioning

confidence: 99%

“…However, as mentioned by Ben et al, Riaz et al, and Pritchard, the disturbances which are localized near the reaction front cannot be accurately captured in the

(normalτ, z)

domain, since the dominant operator,

\partial^{2} true/ \partial z^{2}

does not have localized eigenfunctions that vanish at the semi‐infinite boundary. Following their suggestion, we transform Equations and (32) in a similar manner to the

(normalτ, normalζ)

domain as follows:

τ \frac{\partial {normalθ}_{1}}{\partial τ} - \frac{normalζ}{2} D {normalθ}_{1} + \sqrt{normalτ} w_{1} D {normalθ}_{0} = true(D^{2} - k^{*}^{2} true) {normalθ}_{1}

true(D^{2} - k^{*}^{2} true) w_{1}^{-} = - k^{*}^{2} G_{A} {normalθ}_{1} f o r ζ < {normalζ}_{f}

true(D^{2} - k^{*}^{2} true) w_{1}^{+} = k^{*}^{2} true(G_{B} - G_{C} true) {normalθ}_{1} f o r ζ \geq {normalζ}_{f}

where

D = \partial true/ \partial ζ

and

k^{*}

…”

Section: Theoretical Analysismentioning

confidence: 99%

“…These solutions were already given by Kim. [21] For the case of G A ¼ G C À G B ð Þ , chemical reaction effect can be negligible, and all the solutions given in Equations (A1-A4) are reduced Equations (A7-A8), which are obtained for the non-reactive system. It should be noted that for the above limiting cases the following relation was already shown: [21] Z 1 0 c m f n dz ¼…”

Section: Nonlinear Numerical Simulation (Nns)mentioning

confidence: 99%

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Linear and nonlinear analyses of the effect of chemical reaction on the onset of buoyancy‐driven instability in a CO₂ absorption process in a porous medium or Hele‐Shaw cell

Kim

Wylock

2016

Can J Chem Eng

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To understand CO2 absorption into a basic solution saturated porous medium or a Hele‐Shaw cell, the effect of the chemical reaction between dissolved CO2 and the basic reactant in the solution on the onset of a buoyancy‐driven instability in a gas absorption process is analyzed theoretically. For the infinitely fast reaction, new linear and non‐linear stability equations are derived without the quasi‐steady state assumption (QSSA) and solved analytically. The present stability analysis without the QSSA shows that the important parameters are the dimensionless densification numbers and the reactant concentration ratio. For the physically unstable system, the chemical reaction can induce a non‐monotonic density profile and has an important effect on the onset of instability motion. The effect of the reactant concentration ratio on the stability of the system is strongly dependent on the physical situation. Here, we call the system which is physically stable when there is no chemical reaction as the physically stable system. Even for this physically stable system, the chemical reaction makes the system unstable and induces the gravitational fingering instability motion. Also, it is found that the stability of the physically stable system is relatively insensitive to the non‐monotonicity of the density profile.

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“…Em regiões próximas à parede ocorre a formação da camada limite, a qual pode dar origem a intensos gradientes das propriedades de fluxo. Esse fenômeno acontece devido a condição de não escorregamento (non-slip), ou seja, as partículas de fluido se aderem à superfície da parede por causa de sua viscosidade, assim possuindo as mesmas velocidades (Pritchard;Leylegian, 2011).…”

Section: Modelagem Do Fluxo Próximo à Paredeunclassified

Otimização das características geométricas de um conversor de torque automotivo

Alex Barros de Mattos

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Sinking inside the box

Cited by 5 publications

References 11 publications

Modeling and Performance Analysis of Different Gas–Bioparticle Cyclone Separators: CFD–DEM Simulations

Modeling and Performance Analysis of Different Gas–Bioparticle Cyclone Separators: CFD–DEM Simulations

Linear and nonlinear analyses of the effect of chemical reaction on the onset of buoyancy‐driven instability in a CO₂ absorption process in a porous medium or Hele‐Shaw cell

Otimização das características geométricas de um conversor de torque automotivo

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Sinking inside the box

Cited by 5 publications

References 11 publications

Modeling and Performance Analysis of Different Gas–Bioparticle Cyclone Separators: CFD–DEM Simulations

Modeling and Performance Analysis of Different Gas–Bioparticle Cyclone Separators: CFD–DEM Simulations

Linear and nonlinear analyses of the effect of chemical reaction on the onset of buoyancy‐driven instability in a CO2 absorption process in a porous medium or Hele‐Shaw cell

Otimização das características geométricas de um conversor de torque automotivo

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Linear and nonlinear analyses of the effect of chemical reaction on the onset of buoyancy‐driven instability in a CO₂ absorption process in a porous medium or Hele‐Shaw cell