Review
Engineering, Chemical
Alberto Di Renzo, Erasmo S. Napolitano, Francesco P. Di Maio
Summary: In the past decade, the application of CFD-DEM for fluidized beds has expanded from small, lab-scale units to larger scale systems, benefiting greatly from coarse graining methods. By introducing coarse graining procedures based on different physical backgrounds, the number of particles that can be simulated has increased, covering pilot-scale and industrially relevant systems. The review discusses scaling for contact forces, hydrodynamic forces, and cohesive forces, quantifying computational savings in terms of coarse graining degree and presenting recent applications and future directions in the field.
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, Environmental
Xiaojian Yang, Yufeng Wei, Wei Shyy, Kun Xu
Summary: The gas-solid particle two-phase flow in a fluidized bed is studied using a multi-scale algorithm that combines the gas-kinetic scheme (GKS) for the gas phase and the unified gas-kinetic wave-particle method (UGKWP) for the solid particle phase. The UGKWP seamlessly transitions between wave and discrete particle formulations based on the particle cell's Knudsen number. The algorithm captures the particle phase in different regimes with high accuracy and efficiency.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Mechanics
Liheng Guan, Jorge Salinas, Nadim Zgheib, S. Balachandar
Summary: Excluding particle rotation without ignoring associated tangential collision forces significantly reduces particle flux, while excluding both particle rotation and tangential collision forces results in practically unchanged particle flux but slightly increased excess Shields stress. Additionally, the lift force is found to substantially influence particle flux.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2021)
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
Computer Science, Interdisciplinary Applications
H. Eshraghi, E. Amani, M. Saffar-Avval
Summary: In this article, new coarse-graining algorithms for simulating particle-laden flows are proposed. The algorithms include variants of the Reproducing Kernel Particle Methods (RKPM) and an extended Diffusion Two-Step Method (DTSM). The performance of the algorithms is compared to other widely-used algorithms, and it is found that the first-order RKPM performs the best in terms of various attributes. However, due to its higher computational cost, the extended DTSM is recommended as an affordable alternative for large-scale problems.
JOURNAL OF COMPUTATIONAL PHYSICS
(2023)
Article
Physics, Multidisciplinary
Timothy Leong, Chandhana Voleti, Zhangli Peng
Summary: A research team developed coarse-grained models to simulate the endocytosis process of the SARS-CoV-2 coronavirus at physiologically relevant spatial and temporal scales. By conducting all-atom simulations and normal mode analysis, they demonstrated the unique flexibility of spike proteins during their interaction with ACE2 receptors, showing that bent configurations make it easier for the spikes to attach to host cell membranes compared to rigid spikes.
FRONTIERS IN PHYSICS
(2021)
Article
Engineering, Chemical
Shuai Lu, Bin Lan, Ji Xu, Bidan Zhao, Zheng Zou, Junwu Wang, Hongzhong Li, Qingshan Zhu
Summary: This study investigates the issue of solids back-mixing in multiple-chamber fluidized beds using coarse-grained CFD-DEM simulations. The results show that optimizing the orifice size, location, and gas velocity in each chamber can partially suppress solids back-mixing. Additionally, using a sufficiently long pipe instead of a baffle with orifice can completely eliminate solids back-mixing.
Article
Engineering, Multidisciplinary
Hongyang Cheng, Anthony R. Thornton, Stefan Luding, Andrew L. Hazel, Thomas Weinhart
Summary: The finite element method (FEM) is commonly used for modeling continuum media, while the discrete element method (DEM) is used for discrete systems. This paper introduces the coupling between discrete and continuum methods by mapping discrete particle data onto smooth fields. The authors found that using this coarse-graining approach leads to more accurate results, reduced energy generation, and less numerical dissipation.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2023)
Article
Engineering, Chemical
Ying Jia, Yong Zhang, Ji Xu, Chenlong Duan, Yuemin Zhao, Wei Ge
Summary: This study utilized a coarse-grained CFD-DEM method to analyze the bed expansion rates and solid concentration in ADMFB, and evaluated the microscale and mesoscale behaviors of ADMFB through power spectrum density and wavelet decomposition. The research found that pressure fluctuation mainly resulted from bubbles motion of mesoscale rather than from particles motion of microscale and global bed expansion of macroscale.
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.
Review
Engineering, Chemical
Huibin Xu, Weiyu Wang, Chi Ma, Wenqi Zhong, Aibing Yu
Summary: This article reviews the recent studies on the fluidization characteristics of wet particles in fluidized beds and spouted beds, including physical experiments and numerical simulations. The findings of these studies are important for the industrial applications of wet particle fluidization, aiding in the scale-up, design, and optimization of processes. The focus of the physical experiments is on the development of new measurement methods and related findings, while the focus of the numerical simulations is on the development of discrete element method (DEM) to provide new insights into wet particle fluidization at the particle scale. The challenges and needs for future research on wet particle fluidization are also discussed.
Article
Computer Science, Interdisciplinary Applications
Joseph Bakarji, Daniel M. Tartakovsky
Summary: Statistical (machine learning) tools for equation discovery require large amounts of data, typically computer generated rather than experimentally observed. Learning on simulated data in areas such as multiscale modeling and stochastic simulations can lead to discovery. Our machine-learning strategy based on sparse regression replaces human discovery of models and can be executed in two modes.
JOURNAL OF COMPUTATIONAL PHYSICS
(2021)
Review
Biochemistry & Molecular Biology
Tiedong Sun, Vishal Minhas, Nikolay Korolev, Alexander Mirzoev, Alexander P. Lyubartsev, Lars Nordenskiold
Summary: This review presents some well-developed bottom-up coarse-graining methods for effective modeling of DNA properties, such as DNA flexibility, conformation, melting, and condensation, based on underlying atomistic force field simulations. These methods separate fast and slow dynamic processes in molecular systems and construct coarse-grained Hamiltonian using pair-wise additive potential for efficiency in computer simulation.
FRONTIERS IN MOLECULAR BIOSCIENCES
(2021)
Article
Engineering, Chemical
Shijiao Li, Peng Zhao, Ji Xu, Li Zhang, Junwu Wang
Summary: This study investigates the fluidization of polydisperse particles in bubbling micro-fluidized beds using CFD-DEM. The study validates the method by comparing it with experimental measurements and then performs a detailed analysis of bed hydrodynamics. The results show that particle size distribution enhances fluidization quality and that significant axial segregation is observed only in the case of wide PSD. The study provides insights into the role of PSD in gas fluidization and the similarities and differences between micro and large fluidized beds.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Engineering, Chemical
Yundi Jiang, Xiao Chen, Jari Kolehmainen, Ioannis G. Kevrekidis, Ali Ozel, Sankaran Sundaresan
Summary: The study demonstrated the successful extrapolation of an artificial neural network model to large grid sizes and developed a general model for drag correction that can be applied to various gas and particle characteristics. This is important for understanding the behavior of gas-particle flows on a large scale.
CHEMICAL ENGINEERING SCIENCE
(2021)
Article
Instruments & Instrumentation
Paris Blaisdell-Pijuan, Zhe Chen, Yiteng Zhang, Sankaran Sundaresan, Bruce Koel, Claire Gmachl
Summary: The use of mid-infrared light to excite gas-phase reactants in heterogeneous catalytic processes can enhance energy efficiency, but close coupling between light-excited molecules and the catalyst is a primary challenge. By combining directional hemispherical measurements with in-line transmission measurements, it is possible to directly measure the scattered light signal, which is crucial for studying scattering behavior.
APPLIED SPECTROSCOPY
(2021)
Review
Engineering, Chemical
Victor Francia, Lyes Ait Ali Yahia, Raffaella Ocone, Ali Ozel
Summary: The design of new technology for processing and manufacturing particulate products requires understanding granular rheology. Powders display complex behaviour due to their ability to rearrange under stress, generally classified into three flow regimes. The characterisation of flowability is usually restricted to the flow initiation in quasi-static regime.
KONA POWDER AND PARTICLE JOURNAL
(2021)
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
Pharmacology & Pharmacy
Mostafa Sulaiman, Xiaoyu Liu, Sankaran Sundaresan
Summary: The study used Computational Fluid Dynamics-Discrete Element Method simulations to investigate the transport and aerosolization of particles in different dry powder inhaler geometries. The research found that geometry modifications can significantly impact aerosolization quality and device performance.
INTERNATIONAL JOURNAL OF PHARMACEUTICS
(2021)
Article
Pharmacology & Pharmacy
Josh Williams, Jari Kolehmainen, Steve Cunningham, Ali Ozel, Uwe Wolfram
Summary: For many respiratory disease patients, managing their condition with inhalers improves their breathing ability; however, poor disease management and increasing pollution can lead to exacerbations. Drug deposition in the throat instead of the lungs limits symptom relief. Studies on aerosol inhalation suggest that patient-specific computational models can optimize drug delivery to the lungs, but often fail to account for impaired breathing scenarios, such as during recovery from an exacerbation. Our research reveals that image-based airway models are crucial for accurate respiratory modeling and various inhalation profiles should be tested for optimal prediction of inhaler deposition.
INTERNATIONAL JOURNAL OF PHARMACEUTICS
(2022)
Article
Physics, Applied
Zhe Chen, Bruce E. Koel, Sankaran Sundaresan
Summary: Ammonia synthesis experiments were carried out in a coaxial dielectric barrier discharge (DBD) reactor packed with various supports and metal catalysts. The addition of packed bed particles led to a significant increase in the reaction rate. Kinetic analysis revealed that ammonia synthesis mainly proceeds by the adsorption of reactive radicals in the gas phase and subsequent reactions on metal and support material surfaces.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Chemistry, Physical
Hao Zhao, Guohui Song, Zhe Chen, Xiaofang Yang, Chao Yan, Shota Abe, Yiguang Ju, Sankaran Sundaresan, Bruce E. Koel
Summary: Ammonia synthesis at 533 K and atmospheric pressure was investigated in a plasma reactor without packing and with catalyst particles. Gas-phase species NNH and N2H2 were identified and their importance in plasma-assisted ammonia synthesis was demonstrated. The study showed the significance of in situ identification of gas-phase species for studying the kinetics of plasma-assisted catalysis.
ACS ENERGY LETTERS
(2022)
Article
Multidisciplinary Sciences
Uwe Wolfram, Marta Pena Fernandez, Samuel McPhee, Ewan Smith, Rainer J. Beck, Jonathan D. Shephard, Ali Ozel, Craig S. Erskine, Janina Buscher, Jurgen Titschack, J. Murray Roberts, Sebastian J. Hennige
Summary: Ocean acidification threatens deep-sea corals, leading to rapid loss of their reef habitat. Through experiments and models, we found that cold-water corals have remarkable mechanical properties, with strength surpassing concrete and nacre. Despite future oceanic conditions, their strength remains, albeit with reduced stiffness. Our models demonstrate how increased porosity increases the risk of coral habitat destruction. These findings aid conservation and management efforts for vulnerable marine ecosystems.
SCIENTIFIC REPORTS
(2022)
Article
Mechanics
J. Williams, U. Wolfram, A. Ozel
Summary: In dilute turbulent particle-laden flows, the effects of fluid velocity fluctuations on particle dynamics are significant. To address this issue, a stochastic differential equation approach with neural network modeling and large-eddy simulation is proposed. The proposed model shows good predictability for particle transport and dispersion compared to direct numerical simulations.
Article
Chemistry, Physical
Zhe Chen, Surabhi Jaiswal, Ahmed Diallo, Sankaran Sundaresan, Bruce E. Koel
Summary: This study investigates the effect of catalyst support particle porosity on the conversion of NH3 synthesis. The results show that porous silica particles have higher conversion rate and energy yield. High-resolution optical emission spectra indicate that the concentrations of active species in the plasma discharge are lower for the porous material, suggesting their involvement in heterogeneous reactions.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Chemistry, Physical
Hang Zhang, Sankaran Sundaresan, Michael A. Webb
Summary: The wettability of a polymer surface, determined by its hydrophobicity or tendency to repel water, is crucial for its utility. Molecular dynamics simulations are used to investigate the interactions between water and six chemically distinct polymers. The extent of hydrogen bonding between polymer and water is found to be the main factor influencing wettability.
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Article
Engineering, Biomedical
Calum Anderson, Chara Ntala, Ali Ozel, Robert L. Reuben, Yuhang Chen
Summary: This study establishes a computational homogenization framework to quantify the mechanical behavior of prostate tissue, considering its multiphasic heterogeneous microstructures and the mechanical characteristics of tissue constituents. The results show significant anisotropy and tension-compression asymmetry of the apparent behaviors of prostatic tissue, with strong correlation with microstructural indices such as tissue constituent area fractions and tissue fabric tensor. The orientation of stromal tissue plays an essential role in determining the directions of anisotropy and the compression-tension asymmetry characteristics in normal human prostatic tissue.
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING
(2023)
Article
Engineering, Chemical
Yun Zhang, Ali Ozel, Christine M. Hartzell
Summary: Accurate modeling of contact electrification in insulating materials is crucial for predicting and controlling their behavior. This study proposes a mesoscopic model based on the donor-acceptor mechanism, which incorporates findings on surface patch features of identical dielectric materials from experiments. The model enables reproduction of the charge transfer process and development of a macroscopic model that statistically captures this process.
