Multiscale simulation of elongated particles in fluidised beds

Fitzgerald, Barry; Zarghami, Ahad; Mahajan, Vinay V.; Sanjeevi, Sathish K. P.; Mema, Ivan; Vikrant, V.; Hasadi, Yousef M. F. El; Padding, JT Johan

doi:10.1016/j.cesx.2019.100019

Cited by 6 publications

(8 citation statements)

References 241 publications

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“…Porosity is then determined by the amount of these pseudo-particles within each cell. Recently, such methods were employed to volume averaging of nonspherical particles [24][25][26][27] as they are significantly more accurate compared to the PCM. Peng et al [18] introduced the Particle meshing method (PMM) which belongs to the SPM family.…”

Section: Binning Methodsmentioning

confidence: 99%

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Comparative analysis of porosity coarse-graining techniques for discrete element simulations of dense particulate systems

2021

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The Discrete Element Method (DEM) is a well-established approach to study granular materials in numerous fields of application; modelling each granular particle individually to predict the overall behavior. This behavior can be then extracted by averaging, or coarse graining, the sample using a suitable method. The choice of appropriate coarse-graining method entails a compromise between accuracy and computational cost, especially in the large-scale simulation typically required by industry. A number of coarse-graining methods have been proposed in the literature, these are reviewed and categorized in this work. Within this contribution two novel porosity coarse-graining strategies are proposed including a Voxel method where a secondary dense grid of "pixel-cells" is implemented adopting a binary logic for the coarse graining and a Hybrid method where both analytical formulas and pixels are utilized. The proposed methods are compared with four coarsegraining schemes that have been documented in the literature, including the Particle Centroid Method (PCM), an Analytical method, a method which solves the diffusion equation and an approach which employs averaging using kernels. The novel methods are validated for problems in both two and three dimensions through comparison with the "accurate" Analytical method. It is shown that, once validated, both the proposed schemes can approximate the exact solutions quite accurately, however there is a high computational cost associated with the Voxel method. The accuracy of both methods can be adjusted allowing the user to decide between accuracy and computational time. A detailed comparison is then presented for all six schemes considering "accuracy", "smoothness" and "computational cost". Optimal parameters are obtained for all six methods and recommendations for coarse graining DEM samples are discussed.

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Section: Binning Methodsmentioning

confidence: 99%

“…Additionally, the smoothness of solution in small cells is stated. Particle meshing method (PPM) [18] Satellite point methods [17,[19][20][21][22][23][24][25][26][27] Exact methods* Difficult Moderate Difficult Yes (if Δx>~2dp) Easy…”

Section: Binning Methodsmentioning

confidence: 99%

Comparative analysis of porosity coarse-graining techniques for discrete element simulations of dense particulate systems

2021

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“…Characteristic earthquakes with some typical regularity in their recurrence have been a matter of special interest in seismology. Prominent examples of earthquakes with characteristic recurrence periods are the Parkfield earthquake sequence (Wiemer and Wyss, 1997) and also the episodic tremor and slip (ETS) events recorded in Japan, Cascadia, and Hikurangi subduction systems (Gomberg, 2010). Such events are typically modelled by spring-slider models based on empirical friction data (Ohtani et al, 2019).…”

Section: Application Of Two Reaction-self-diffusion Equations To Characteristic Earthquakesmentioning

confidence: 99%

“…An incorporation of Arrhenius-dependent thermal regularization on the continuum damage model can be found in Hu et al (2017). The middle row shows a dissipative particle dynamics approach (modified after Español and Warren, 2017) and the bottom row a lattice Boltzmann homogenization technique (modified after Fitzgerald et al, 2019). Our approach replaces the explicit simulations by considering the meso-scale processes through consideration of non-local effects of cross-diffusion.…”

Section: Introductionmentioning

confidence: 99%

Cross-diffusion waves resulting from multiscale, multiphysics instabilities: application to earthquakes

Regenauer-Lieb

Schrank

et al. 2021

Solid Earth

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Abstract. Theoretical approaches to earthquake instabilities propose shear-dominated source mechanisms. Here we take a fresh look at the role of possible volumetric instabilities preceding a shear instability. We investigate the phenomena that may prepare earthquake instabilities using the coupling of thermo-hydro-mechano-chemical reaction–diffusion equations in a THMC diffusion matrix. We show that the off-diagonal cross-diffusivities can give rise to a new class of waves known as cross-diffusion or quasi-soliton waves. Their unique property is that for critical conditions cross-diffusion waves can funnel wave energy into a stationary wave focus from large to small scale. We show that the rich solution space of the reaction–cross-diffusion approach to earthquake instabilities can recover classical Turing instabilities (periodic in space instabilities), Hopf bifurcations (spring-slider-like earthquake models), and a new class of quasi-soliton waves. Only the quasi-soliton waves can lead to extreme focussing of the wave energy into short-wavelength instabilities of short duration. The equivalent extreme event in ocean waves and optical fibres leads to the appearance of “rogue waves” and high energy pulses of light in photonics. In the context of hydromechanical coupling, a rogue wave would appear as a sudden fluid pressure spike. This spike is likely to cause unstable slip on a pre-existing (near-critically stressed) fault acting as a trigger for the ultimate (shear) seismic moment release.

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“…Analogously, the lift force for the spherocylinders is defined as (10) and the definition of ê lift given in Mema et al [27] is used, which calculates the expected lift force direction based on the particle's orientation with respect to the slip-velocity. Note that the values F drag and F lift can be negative in case the drag force acts into the opposite direction of the slip-velocity or the lift force acts into the opposite direction of ê lift , respectively.…”

Section: Particle-fluid Forcesmentioning

confidence: 99%

Analysis of Mobility Effects in Particle‐Gas Flows by Particle‐Resolved LBM‐DEM Simulations

Rosemann

Reinecke

Kruggel‐Emden

2020

Chemie Ingenieur Technik

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This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Dedicated to Prof. Dr.-Ing. Matthias Kraume on the occasion of his 65th birthday Particle-resolved direct numerical simulations are performed to simulate the flow through particle assemblies that are either static or freely moving to demonstrate the influence of particle mobility. To obtain a comprehensive understanding for this influence essential parameters such as the Reynolds number, solids volume fraction, particle-fluid density ratio, collision parameters and particle shape are varied. The influence of particle mobility is assessed by evaluating the particlefluid forces, the particle ensemble structure and particle velocities. It is found that the ability of existing correlations for static particle systems to predict drag and lift forces correctly in dynamic particle-gas flows is limited and that drift forces perpendicular to the drag force play an important role.

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Multiscale simulation of elongated particles in fluidised beds

Cited by 6 publications

References 241 publications

Comparative analysis of porosity coarse-graining techniques for discrete element simulations of dense particulate systems

Comparative analysis of porosity coarse-graining techniques for discrete element simulations of dense particulate systems

Cross-diffusion waves resulting from multiscale, multiphysics instabilities: application to earthquakes

Analysis of Mobility Effects in Particle‐Gas Flows by Particle‐Resolved LBM‐DEM Simulations

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