Predicting the impact of particle-particle collisions on turbophoresis with a reduced number of computational particles

Johnson, Perry L.

doi:10.1016/j.ijmultiphaseflow.2019.103182

Cited by 17 publications

(12 citation statements)

References 39 publications

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“…The relatively flat concentration profiles were consistent with the relatively flat particle wall-normal velocity profiles (figure 14b). The high wall-normal particle velocity near the wall serves to disperse particles, disrupting turbophoresis, and is consistent with the higher volume fraction considered in this work (Johnson 2020). It is important to note there is a small but noticeable increase in particle concentration inside y/δ < 0.05.…”

Section: Fluid Statisticssupporting

confidence: 85%

“…The lack of turbophoresis observed can be explained in part owing to the volume fraction considered in this study. Johnson (2020) showed under a similar turbulence intensity and Stokes number that wall concentration monotonically decreased with increasing volume fraction. The relatively flat concentration profiles were consistent with the relatively flat particle wall-normal velocity profiles (figure 14b).…”

Section: Fluid Statisticsmentioning

confidence: 80%

“…Although requiring more investigation, this suggests adoption of Balachandar et al's (2019) correlation to extend the Stokesian DGF or, in other words, the discrete Landau-Squire type solution (Batchelor 1967) to finite Reynolds number (nonlinear regime) could possibly serve as a basis for extending DGF to other (nonlinear) partial differential equations with source terms.) In a similar fashion, the Esmaily & Horwitz (2018) method was pushed to the edge of its applicability in the near-wall region, but recent work (Pakseresht, Esmaily & Apte 2019, 2020 has shown the method of Esmaily & Horwitz (2018) can be extended to the wall-bounded regime. Both the Oseen DGF method and extended Esmaily & Horwitz (2018) method are comparably accurate point-particle strategies at all wall-normal separations for turbulent channel flow simulation and would likely yield similar predictions over a range of the particle-laden flow parameter phase space.…”

Section: Discussionmentioning

confidence: 99%

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The discrete Green's function paradigm for two-way coupled Euler–Lagrange simulation

et al. 2021

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We outline a methodology for the simulation of two-way coupled particle-laden flows. The drag force that couples fluid and particle momentum depends on the undisturbed fluid velocity at the particle location, and this latter quantity requires modelling. We demonstrate that the undisturbed fluid velocity, in the low particle Reynolds number limit, can be related exactly to the discrete Green's function of the discrete Stokes equations. In addition to hydrodynamics, the method can be extended to other physics present in particle-laden flows such as heat transfer and electromagnetism. The discrete Green's functions for the Navier–Stokes equations are obtained at low particle Reynolds number in a two-plane channel geometry. We perform verification at different Reynolds numbers for a particle settling under gravity parallel to a plane wall, for different wall-normal separations. Compared with other point-particle schemes, the Stokesian discrete Green's function approach is the most robust at low particle Reynolds number, accurate at all wall-normal separations. To account for degradation in accuracy away from the wall at finite Reynolds number, we extend the present methodology to an Oseen-like discrete Green's function. The extended discrete Green's function method is found to be accurate within $6\,\%$ at all wall-normal separations for particle Reynolds numbers up to 24. The discrete Green's function approach is well suited to dilute systems with significant mass loading and this is highlighted by comparison against other Euler–Lagrange as well as particle-resolved simulations of gas–solid turbulent channel flow. Strong particle–turbulence coupling is observed in the form of turbulence modification and turbophoresis suppression, and these observations are placed in context of the different methods.

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Section: Fluid Statisticssupporting

confidence: 85%

Section: Fluid Statisticsmentioning

confidence: 80%

Section: Discussionmentioning

confidence: 99%

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The discrete Green's function paradigm for two-way coupled Euler–Lagrange simulation

et al. 2021

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“…2001; Yamamoto et al. 2001; Caraman, Borée & Simonin 2003; Kuerten & Vreman 2015; Johnson 2020), we neglect collisions between particles in simulations because we found that the probability of particle–particle collision within the maximum concentration grid is smaller than , while the extra computational cost for collision searching is rather high. Furthermore, the results of Li et al.…”

Section: Methodsmentioning

confidence: 99%

Modulation of turbulence by saltating particles on erodible bed surface

2021

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“…SPs are released on boundaries and domains uniformly, according to the underlying mesh, as defined by a grid. Usually, a particle simulation suffers from too many particles in the total system [59]. Since the SP size can only be increased to a specific limit, the high number of SPs released in each channel can render the computation slow and costly.…”

Section: Effect Of Number Of Spsmentioning

confidence: 99%

Particle Dynamics-Based Stochastic Modeling of Carbon Particle Charging in the Flow Capacitor Systems

Summer¹,

Torop²,

Aabloo³

et al. 2022

Applied Sciences

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Aqueous electrochemical flow capacitors (EFCs) have demonstrated high-power capabilities and safety at low cost, making them promising energy storage devices for grid applications. A primary performance metric of an EFC is the steady-state electrical current density it can accept or deliver. Performance prediction, design improvements, and up-scaling are areas in which modeling can be useful. In this paper, a novel stochastic superparticle (SP) modeling approach was developed and applied to study the charging of carbon electrodes in the EFC system, using computational superparticles representing real carbon particles. The model estimated the exact values of significant operating parameters of an EFC, such as the number of particles in the flow channel and the number of electrolytic ions per carbon particle. Optimized model parameters were applied to three geometrical designs of an EFC to estimate their performance. The modeling approach allowed study of the charge per carbon particle to form the electric double-layer structure. The linear relationship between the concentration of SPs and the ionic charge was observed when optimized at a constant voltage of 0.75 V. The simulation results are in excellent agreement with experimental data, providing a deep insight into the performance of an EFC and identifying limiting parameters for both engineers and material scientists to consider.

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Predicting the impact of particle-particle collisions on turbophoresis with a reduced number of computational particles

Cited by 17 publications

References 39 publications

The discrete Green's function paradigm for two-way coupled Euler–Lagrange simulation

The discrete Green's function paradigm for two-way coupled Euler–Lagrange simulation

Modulation of turbulence by saltating particles on erodible bed surface

Particle Dynamics-Based Stochastic Modeling of Carbon Particle Charging in the Flow Capacitor Systems

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