Article
Engineering, Chemical
V. Brandt, J. Grabowski, N. Jurtz, M. Kraume, H. Kruggel-Emden
Summary: DEM-CFD is computationally demanding and limited to lab-scale systems, so coarse-graining approaches are used to summarize particles. This study compares force scaling models in different beds to eliminate influences and identifies optimal scaling rules based on physical parameters. It also analyzes fluidized beds to determine the suitability of scaling models for systems governed by both contact and hydrodynamic forces, providing recommendations for future simulations of industrial-scale particle systems.
Article
Engineering, Chemical
Erasmo S. Napolitano, Alberto Di Renzo, Francesco P. Di Maio
Summary: The design, scale-up and operation of cyclone gas-solid separators are mostly based on simplified models and experience, but previous simulations are not applicable for high-load operations with large particles. The use of DEM-CFD simulations allows for four-way coupled dense flow but is computationally expensive. Coarse-graining methods have been proposed to reduce the computational cost, but more research is needed to understand the trade-off between accuracy and speed-up. This study investigates a coarse-grain DEM-CFD approach for simulating two-phase flow in a cyclone and finds that while macroscopic quantities are maintained, detailed features of the gas and solids flow are affected by the level of coarse graining.
SEPARATION AND PURIFICATION TECHNOLOGY
(2022)
Article
Engineering, Chemical
Musango Lungu, John Siame, Lloyd Mukosha
Summary: This study validates a detailed coarse-grained CFD-DEM model in the open-source code MFIX. The validation metrics include fluidization behavior, minimum fluidization velocity, averaged pressure drop, mean particle velocity, and rms particle velocity. The choice of spring constant impacts fluidization dynamics, and the Tang et al. (2015) drag correlation performs well at higher velocities. The coarse-grained model predicts a lower minimum fluidization velocity, and the error in average pressure drop reduces with increasing statistical weight at low gas velocities. The mean particle velocity profiles show no significant differences between the coarse-grained and conventional CFD-DEM models, while the rms profiles decrease with increasing statistical weight. Additionally, there is a gain in wall clock time for completing a case using the coarse-grained model.
Article
Engineering, Chemical
Chih-Chia Huang, Jeroen A. van Oijen, Niels G. Deen, Yali Tang
Summary: The combination of coarse-graining discrete element method (CG-DEM) with the Flamelet Generated Manifold-Large Eddy Simulation (FGM-LES) approach reduces computational burden in simulating turbulent coal combustion. The developed method maintains good accuracy and cost-effectiveness compared to conventional reactive simulations. An optimal coarse-graining factor of 2 is determined for predicting pulverized coal flow dynamics and combustion performance effectively.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Engineering, Chemical
Suranita Kanjilal, Simon Schneiderbauer
Summary: The study focuses on numerical modeling of mixing and transport of lumpy materials using the discrete element method (DEM). By introducing a variable coarse grain ratio, faster computation can be achieved compared to traditional coarse graining, providing more flexibility in reducing the number of particles. Implementation of a correction parameter to address the violation of geometrical similarity resulted from this method leads to fairly good agreement between the revision model, reference DEM simulations, and experimental data.
Article
Engineering, Chemical
Hanqiao Che, Dominik Werner, Jonathan Seville, Tzany Kokalova Wheldon, Kit Windows-Yule
Summary: Computational Fluid Dynamics coupled with Discrete Element Method (CFD-DEM) is a commonly used numerical method for gas-solid flow modeling. Coarse-graining (CG) approaches can reduce the number of particles while maintaining system dynamics. This paper evaluates three typical CG methods for simulating a bubbling fluidized bed and finds that the CG simulation fails when the size ratio between the chamber and particles decreases to approximately 20. It also shows that the specific CG approach for interparticle contact parameters does not substantially affect the simulation results across a wide range of CG factors.
Article
Engineering, Chemical
Hanqiao Che, Catherine O'Sullivan, Adnan Sufian, Edward R. Smith
Summary: This study introduces a new method using a two-grid coarse-graining approach to determine local porosity for particles, which can more accurately predict fluid-particle interactive force for polydisperse particle systems compared to alternative methods in unresolved CFD-DEM codes.
Article
Engineering, Chemical
Zhaohua Jiang, Takuya Tsuji, Kimiaki Washino, Toshitsugu Tanaka
Summary: The study found that bubble size in bubbling fluidized beds is influenced by the model particle size, and coarse spatial resolution increases bubble size and decreases the number of bubbles. However, in practical coarse-graining scenarios, the countervailing influence of model particle size and spatial resolution results in nearly the same bubble size.
ADVANCED POWDER TECHNOLOGY
(2021)
Article
Thermodynamics
Genevieve Soon, Hui Zhang, Adrian Wing-Keung Law, Chun Yang
Summary: The study extends the formulation of the CFD-DEM method, CD-MELT, to include melting in three phases (gas, liquid, and solid). The new CD-MELT method characterizes the individual phases separately, allowing for more accurate simulation of the melting process. The inclusion of latent heat and sensible heat through the introduction of a particle enthalpy variable enables the consideration of non-isothermal melting. CD-MELT provides insights into the movement of melted liquid and gas channel formations, which cannot be obtained using the current VOF approaches.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Engineering, Chemical
M. J. A. de Munck, J. B. van Gelder, E. A. J. F. Peters, J. A. M. Kuipers
Summary: Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) is a numerical tool used for detailed fluidized bed studies. To overcome its computational expense, coarse-graining techniques have been developed. In this study, we compared the effectiveness of different coarse-graining scaling laws in characterizing the original system. We also demonstrated the usefulness of a continuous two-way smoothing function in achieving grid-independent solutions in CFD-DEM simulations.
CHEMICAL ENGINEERING SCIENCE
(2023)
Article
Engineering, Chemical
Stefan Madlmeir, Stefan Radl
Summary: The Discrete Element Method (DEM) is commonly used for modeling the flow of particulate materials. To reduce computational demand, parcels are introduced by coarse graining, which requires sophisticated models to preserve the original behavior. This study extends the coarse-graining concepts by introducing models for particle-fluid mass transfer and spray deposition rate, enabling precise particle-droplet-air interaction modeling at low computational cost for spray coating processes.
ADVANCED POWDER TECHNOLOGY
(2022)
Article
Engineering, Chemical
M. J. A. de Munck, E. A. J. F. Peters, J. A. M. Kuipers
Summary: Computational Fluid Dynamics - Discrete Element Method (CFD-DEM) is widely used for heat transfer modeling in gas-solid fluidized beds. This study introduces a technique of coarse-grained CFD-DEM to overcome computational limitations and simulate larger fluidized beds. A scaling law commonly used for coarse-graining hydrodynamics is generalized to gas-solid heat transfer. The approach is successfully tested for different gas velocities, providing accurate predictions of particle temperatures and Nusselt numbers.
CHEMICAL ENGINEERING SCIENCE
(2023)
Article
Pharmacology & Pharmacy
Xiaoyu Liu, Mostafa Sulaiman, Jari Kolehmainen, Ali Ozel, Sankaran Sundaresan
Summary: This study evaluated the effectiveness of two coarse-grained CFD-DEM approaches in drug delivery via dry powder inhalers, finding that the representative particle approach can approximate CFD-DEM results with reasonable accuracies.
INTERNATIONAL JOURNAL OF PHARMACEUTICS
(2021)
Article
Mechanics
Junsheng Zeng, Baoqing Meng, Jun Chen, Baolin Tian
Summary: In this study, a coarse-grained criterion for simulating compressible particulate two-phase flows was proposed based on similarity invariants and regime transition behaviors. Benchmark cases were used to investigate the validity of the proposed criterion. It was shown that scaling the stiffness coefficient according to the parcel size and reducing the restitution coefficient can maintain the invariance of the spreading velocity of the particle stress wave and recover the internal energy dissipation inside the parcels. An adaptive interpolation operator was introduced to adjust the influencing range of the Lagrangian parcels dynamically for more accurate description of regime transition behaviors.
Article
Engineering, Environmental
Shaotong Fu, Limin Wang
Summary: A new algorithm called unresolved LBM-DEM is proposed for discrete particle simulation. It combines lattice Boltzmann method (LBM) for fluid phase and discrete element method (DEM) for particle phase, with immersed moving boundary (IMB) used for gas-solid coupling. The method has advantages in resolving Geldart A particles and computational efficiency, with GPU parallel computation implemented. Validation tests showed good agreement with experimental data and one to two orders of magnitude speed up compared to traditional algorithms. This suggests unresolved LBM-DEM as a promising strategy for fluidization and multiphase flows.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Engineering, Chemical
Francesca Orsola Alfano, Alberto Di Renzo, Francesco Paolo Di Maio, Mojtaba Ghadiri
Summary: Triboelectric charging has a significant impact on bulk powder flow behavior, especially in pharmaceutical particles; the charge-to-surface area ratio is close to equilibrium value for different materials; aerodynamic dispersion shows great potential for inducing triboelectric charge transfer.
Editorial Material
Engineering, Chemical
Alberto Di Renzo, Fabrizio Scala, Stefan Heinrich
Article
Engineering, Chemical
Francesca Orsola Alfano, Andrea Benassi, Roberto Gaspari, Alberto Di Renzo, Francesco Paolo Di Maio
Summary: Fine particle lift and aerodispersion play crucial roles in delivering active pharmaceutical ingredient (API) powder to patient lungs. Computational fluid dynamics-discrete element method (DEM) simulations are used to characterize the flow field of air and API-coated carrier particles in a swirl-based DPI geometry, providing valuable insights into microscopic mechanisms.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2021)
Article
Engineering, Chemical
Erasmo S. Napolitano, Alberto Di Renzo, Francesco P. Di Maio
Summary: The design, scale-up and operation of cyclone gas-solid separators are mostly based on simplified models and experience, but previous simulations are not applicable for high-load operations with large particles. The use of DEM-CFD simulations allows for four-way coupled dense flow but is computationally expensive. Coarse-graining methods have been proposed to reduce the computational cost, but more research is needed to understand the trade-off between accuracy and speed-up. This study investigates a coarse-grain DEM-CFD approach for simulating two-phase flow in a cyclone and finds that while macroscopic quantities are maintained, detailed features of the gas and solids flow are affected by the level of coarse graining.
SEPARATION AND PURIFICATION TECHNOLOGY
(2022)
Article
Engineering, Chemical
F. O. Alfano, F. P. Di Maio, A. Di Renzo
Summary: The performance of dry powder inhalers depends on the optimal combination of drug research and device design. Coating larger carrier particles to improve flowability is a common solution to overcome the challenges of API's poor flowability. High loading on the carrier particles increases the likelihood of insufficient deagglomeration or reagglomeration. Advanced CFD-DEM simulations were used to investigate API deaggregation in a swirl-based DPI with different carrier particles. The results show that highly loaded salbutamol is delivered more effectively.
Article
Engineering, Chemical
Francesca Orsola Alfano, Alberto Di Renzo, Roberto Gaspari, Andrea Benassi, Francesco Paolo Di Maio
Summary: Powder deaggregation is crucial for drug effectiveness in Dry Powder Inhalers (DPI) with carrier-based formulations. This study uses DEM simulation to investigate the detachment of fine and cohesive API particles. The results are analyzed using an analytical model and compared to commercial devices.
Article
Engineering, Chemical
Francesca Orsola Alfano, Martin Sommerfeld, Francesco Paolo Di Maio, Alberto Di Renzo
Summary: This study analyzed the dispersion and discharge process of particles in carrier-based dry powder inhalers using discrete element method simulations. The simulations focused on the solid phase interactions and provided a mapping of particle-wall collisions and the tracking of particle paths until discharge. The research is valuable for understanding the interactions between particles inside the capsule and their impact on the discharge process.
ADVANCED POWDER TECHNOLOGY
(2022)