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DEM simulations of die filling during pharmaceutical tabletting

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Particuology 2008年第6期6卷 412-418页

作者： chuan-yu wu School of Chemical Engineering University of Birmingham Edgbaston Birmingham B15 2TT UK

The flow behaviour of powders from a stationary shoe into a moving die, which mimics the die filling process in a rotary tablet press, was analysed using a discrete element method （DEM）, in which 2D irregular shaped particles were considered. The influence of the particle shape, size and size distribution, the number of particles used in the simulation, the initial height of powder bed in the shoe, and the filling speed on the average mass flow rate and the critical filling speed （the highest speed at which the die can be completely filled） were explored. It has been found that a maximum flow rate is obtained at the critical filling speed for all systems investigated and poly-disperse systems have higher mass flow rates and higher critical filling speeds than mono-disperse systems. In addition, the powder with particles which can tessellate generally has a lower filling rate and a lower critical titling speed.

关键词： DEM Die filling Tabletting Powder compaction Mass flow rate Critical filling speed

DEM analysis of the effect of electrostatic interaction on particle mixing for carrier-based dry powder inhaler formulations

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Particuology 2015年第6期13卷 25-30页

作者： Jiecheng Yang chuan-yu wu Michael Adams School of Chemical Engineering University of Birmingham Birmingham BI5 2Tr UK Department of Chemical and Process Engineering University ofSu-rrey Guildford GU2 ZXH UK

Particle interactions play a significant role in controlling the performance of dry powder inhalers （DPIs）, which mainly arise through van der Waals potentials, electrostatic interactions, and capillary forces. Our aim is to investigate the influence of electrostatic charge on the performance of DPIs as a basis for improv- ing the formulation of the particle ingredients. The mixing process of carrier and active pharmaceutical ingredient （API） particles in a vibrating container is investigated using a discrete element method （DEM）. The number of APl particles attaching to the carrier particle （i.e., contact number） increases with increas- ing charge and decreases with increasing container size. The contact number decreases with increasing vibrational velocity amplitude and frequency. Moreover, a mechanism governed by the electrostatic force is proposed for the mixing process. This mechanism is different from that previously proposed for the mixing process governed by van der Waals forces, indicating that long-range and short-range adhesive forces can result in different mixing behaviours.

关键词： Electrostatic Particle mixing Dry powder inhaler Discrete element method

GPU-enhanced DEM analysis of flow behaviour of irregularly shaped particles in a full-scale twin screw granulator

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Particuology 2022年第2期20卷 30-40页

作者： Chao Zheng Nicolin Govender Ling Zhang chuan-yu wu Department of Chemical and Process Engineering University of SurreyGuildford GU27XHUnited Kingdom Department of Mechanical Engineering University of JohannesburgSouth Africa Research Center Pharmaceutical Engineering GmbH Graz 8010Austria

During twin screw granulation(TSG),small particles,which generally have irregular shapes,agglomerate together to form larger granules with improved ***,how particle shape impacts the conveying characteristics during TSG is not explored nor well *** this study,a graphic processor units(GPUs)enhanced discrete element method(DEM)is adopted to examine the effect of particle shape on the conveying characteristics in a full scale twin screw granulator for the first *** is found that TSG with spherical particles has the smallest particle retention number,mean residence time,and power consumption;while for TSG with hexagonal prism(Hexp)shaped particles the largest particle retention number is obtained,and TSG with cubic particles requires the highest power ***,spherical particles exhibit a flow pattern closer to an ideal plug flow,while cubic particles present a flow pattern approaching a perfect *** is demonstrated that the GPU-enhanced DEM is capable of simulating the complex TSG process in a full-scale twin screw granulator with non-spherical particles.

关键词： Discrete element method Twin screw granulation Non-spherical particle Residence time distribution GPU

DEM/CFD modelling of the deposition of dilute granular systems in a vertical container

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Chinese Science Bulletin 2009年第23期54卷 4318-4326页

作者： yu Shen GUO yu wu chuan-yu School of Chemical Engineering University of Birmingham Edgbaston Birmingham B15 2TT UK

Deposition of granular materials into a container is a general industrial packing process. In this study, the deposition behaviour of dilute granular mixtures consisting of two types of particles that were of the same particle size but different particle densities in the presence of air was numerically analyzed using a coupled discrete element method (DEM) and computational fluid dynamics (CFD). Bilayer granular mixtures with light particles at bottom and heavy particles at top were first simulated. It was found that the presence of air significantly affected the flow behaviour of the bilayer mixtures. For the system with a relatively low initial void fraction, the air entrapped inside the container escaped through the dilated zones induced due to the friction between the powder bed and wall surfaces. The escaping air streams entrained light particles that were originally located at the bottom of the granular system. Consequently, these light particles were migrated to the top of the granular bed at the end of deposition process. More light particles were migrated when the deposition distance was increased. For the system with a high initial void fraction, some light particles penetrated into the top layer of heavy particles and created a mixing zone. Deposition of random mixtures with different initial void fractions was also investigated and the influence of initial void fraction on the segregation behaviour was explored as well. It was found that the increase of void fraction promoted segregation during the deposition in air. It was demonstrated that, for granular mixtures consisting of particles of different air sensitivities, the presence of air had a significant impact on the mixing and segregation behaviour during the deposition.

关键词：模拟系统颗粒沉积差价合约集装箱垂直稀释德国

Mechanistic analysis of solid-liquid flow during injection

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Particuology 2019年第3期17卷 136-145页

作者： Jie Cai chuan-yu wu yu Guo Jiecheng Yang Xiaobao Zhao Department of Chemical and Process Engineering University of Surrey Guildford GU2 7XH UK School of Energy and Mechanical Engineering Nanjing Normal University Nanjing 210042 China School of Aeronautics and Astronautics. Zhejiang University Hangzhou 310058 China

Direct injection of retinal cells into patients' eyes is a new and improved therapeutic method to address cataracts, but one challenge is that the survival rate of cells during injection is very low. To solve this problem, in this study, the force distribution on retinal cells in injectors with two needle shapes was analysed by coupling the discrete element method with computational fluid dynamics and implementation of an immersed boundary method. Two injectors were considered: one with a straight needle and the other with a curved needle. The velocities of retinal cells in the injector with a straight needle were slightly higher than those in the injector with a curved needle. In addition, injection speed greatly affected the force distribution on retinal cells, with the retinal cells near the piston subjected to the highest forces during injection. The forces on retinal cells strengthened with increases in both retinal cell concentration and piston displacement.

关键词： Retinal cells Force distribution Injection DEM-CFD Immersed boundary method

Three-dimensional DEM-CFD analysis of air-flow-induced detachment of API particles from carrier particles in dry powder inhalers

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Acta Pharmaceutica Sinica B 2014年第1期4卷 52-59页

作者： Jiecheng Yang chuan-yu wu Michael Adams School of Chemical Engineering University of BirminghamBirmingham B152TTUK Department of Chemical and Process Engineering University of SurreyGuildford GU27XHUK

Air flow and particle-particle/wall impacts are considered as two primary dispersion mechanisms for dry powder inhalers(DPIs).Hence,an understanding of these mechanisms is critical for the development of *** this study,a coupled DEM-CFD(discrete element method-computational fluid dynamics)is employed to investigate the influence of air flow on the dispersion performance of the carrier-based DPI formulations.A carrier-based agglomerate is initially formed and then dispersed in a uniformed air *** is found that air flow can drag API particles away from the carrier and those in the downstream air flow regions are prone to be ***,the influence of the air velocity and work of adhesion are also *** is shown that the dispersion number(i.e.,the number of API particles detached from the carrier)increases with increasing air velocity,and decreases with increasing the work of adhesion,indicating that the DPI performance is controlled by the balance of the removal and adhesive *** is also shown that the cumulative Weibull distribution function can be used to describe the DPI performance,which is governed by the ratio of the fluid drag force to the pull-off force.

关键词： Dry powder inhaler Dispersion Detachment Air flow DEM-CFD

Numerical simulation of fluid-thermal-structural coupling characteristics of stratospheric non-rigid airship

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Chinese Journal of Aeronautics 2024年第9期37卷 224-236页

作者： Huafei DU Mingyun Lyu chuan yu Yifei wu Yongmei wu Kangwen SUN School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China Linzhou(Ningbo)Technology Co.Ltd Yuyao 315042China

The voluminous stratospheric non-rigid airship is very sensitive to the external thermal *** temperature change of internal gas caused by the variation in the external ther-mal environment and wind speed will lead to a change in the shape and buoyancy of the airship,thereby affecting its flight *** traditional static analysis method is difficult to accurately reflect this fuid-thermal-structural coupling *** this paper,the iterative analysis method was established for the fluid-thermal-structural coupling effect of stratospheric non-rigid airship based on the models of fluid,thermal,and structural *** the load such as the internal thermal effect and external flow field of the airship,the simulation of the thermo-induced structural deformation effect was conducted using Fluent and Abaqus *** influ-ence of local time and external wind speed on the structural deformation,volume,and equilibrium altitude of the airship was *** results demonstrate that,at low wind speed,the influence of aerodynamic pressure on the deformation of the airship is ***,a great amount of heat is carried away by the wind,then the structural deformation caused by internal and external pressure difference is alleviated and the equilibrium altitude of the airship change *** can serve as a guideline for the design and flight test of the long-endurance stratospheric non-rigid airship.

关键词： Altitude change Fluid-thermal-structural coupling Stratospheric non-rigid airship Structural deformation Wind speed

Effect of BaO and MgO on structure and properties of aluminate slag with various CaO/Al_(2)0_(3)ratios

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Journal of Iron and Steel Research International 2024年第1期31卷 204-214页

作者： yu-qi Kong Ting wu Wen-zhi Xia Wen Yang Hai-chuan Wang School of Metallurgical Engineering Anhui University of TechnologyMa’anshan243032AnhuiChina Key Laboratory of Metallurgical Emission Reduction and Resource Recycling(Ministry of Education) Anhui University of TechnologyMa’anshan243002AnhuiChina

To provide theoretical guidance for performance stability control of low-reactive mold fluxes,the effects of BaO and MgO on the structure and properties of aluminate slag with various CaO/Al_(2)0_(3)(C/A)ratios were investigated using the Fourier transform infrared spectrometer,Raman spectroscope,hemispherical melting point instrument,rotational viscometer and X-ray *** results indicated that with BaO and MgO addition,the structure polymerization was first weakened and then enhanced at C/A of 1.1,and the transition contents corresponded to 8 wt.%BaO and 2 wt.%MgO,respectively,while the structure polymerization decreased continuously at C/A of *** the viscosity change was well consistent with the structure evolution,the polymerization degree played a more prominent role in the slag viscosity than superheat degree when the melting temperature difference was within 40℃.The break temperature decreased initially and then increased with augment of BaO and MgO at C/A of 1.1,while it manifested a decrease trend with BaO addition,and it decreased obviously but then turned to increase with MgO increment at C/A of *** crystallization phase and crystallization ratio kept stable with BaO increment,while the crystallization ratio rose greatly with MgO promoting LiAlO_(2)precipitation at C/A of *** crystal types of all experimental slags were mainly Ca_(12)Al_(14)O_(33)and CaF_(2)at C/A of 1.3,and the precipitation of crystalline phase BaAl2O4 demonstrated a rising trend,while that of Ca_(12)Al_(14)O_(33)gradually declined with BaO augment.

关键词： Aluminate slag Structure MgO BaO Viscosity Property

Carbon-based interface engineering and architecture design for high-performance lithium metal anodes

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Carbon Energy 2024年第1期6卷 207-235页

作者： Na Zhu yuxiang Yang yu Li Ying Bai Junfeng Rong chuan wu SINOPEC Research Institute of Petroleum Processing Co. Ltd.BeijingChina Beijing Key Laboratory of Environmental Science and Engineering School of Materials Science and EngineeringBeijing Institute of TechnologyBeijingChina Yangtze Delta Region Academy of Beijing Institute of Technology JiaxingChina

Metallic lithium(Li)is considered the“Holy Grail”anode material for the nextgeneration of Li batteries with high energy density owing to the extraordinary theoretical specific capacity and the lowest negative electrochemical ***,owing to inhomogeneous Li-ion flux,Li anodes undergo uncontrollable Li deposition,leading to limited power output and practical *** materials and their composites with controllable structures and properties have received extensive attention to guide the homogeneous growth of Li to achieve high-performance Li *** this review,the correlation between the behavior of Li anode and the properties of carbon materials is ***,we review emerging strategies for rationally designing high-performance Li anodes with carbon materials,including interface engineering(stabilizing solid electrolyte interphase layer and other functionalized interfacial layer)and architecture design of host carbon(constructing three-dimension structure,preparing hollow structure,introducing lithiophilic sites,optimizing geometric effects,and compositing with Li).Based on the insights,some prospects on critical challenges and possible future research directions in this field are *** is anticipated that further innovative works on the fundamental chemistry and theoretical research of Li anodes are needed.

关键词： carbon materials dendrites hosts interfacial layers Li metal anodes