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CFD modeling of immiscible liquids turbulent dispersion in Kenics static mixers: Focusing on droplet behavior

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Chinese Journal of Chemical Engineering 2020年第2期28卷 348-361页

作者： M.M.Haddadi S.H.Hosseini D.Rashtchian g.ahmadi Chemical and Petroleum Engineering Department Sharif University of TechnologyTehranIran Department of Chemical Engineering Ilam UniversityIlam 69315–516Iran Department of Mechanical and Aeronautical Engineering Clarkson UniversityPotsdamNY 13699-5725USA

The present study is concerned with the computational fluid dynamics(CFD)simulation of turbulent dispersion of immiscible liquids,namely,water–silicone oil and water–benzene through Kenics static mixers using the Eulerian–Eulerian and Eulerian–Lagrangian approaches of the ANSYS Fluent 16.0 *** study the droplet size distribution(DSD),the Eulerian formulation incorporating a population balance model(PBM)was *** the Eulerian–Lagrangian approach,a discrete phase model(DPM)in conjunction with the Eulerian approach for continuous phase simulation was used to predict the residence time distribution(RTD)of *** both approaches,a shear stress transport(SST)k-ωturbulence model was *** validation purposes,the simulated results were compared with the experimental data and theoretical values for the Fanning friction factor,Sauter mean diameter and the mean residence *** reliability of the computational model was further assessed by comparing the results with the available empirical correlations for Fanning friction factor and Sauter mean *** addition,the influence of important geometrical and operational parameters,including the number of mixing elements and Weber number,was *** was found that the proposed models are capable of predicting the performance of the Kenics static mixer reasonably well.

关键词： CFD Liquid–liquid dispersion Kenics static mixer Eulerian–Eulerian approach Eulerian–Lagrangian approach

Multidimensional modeling of the stenosed carotid artery: A novel CAD approach accompanied by an extensive lumped model

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Acta Mechanica Sinica 2014年第2期30卷 259-273页

作者： A.Kashefi M.Mahdinia B.Firoozabadi M.Amirkhosravi g.ahmadi M.S.Saidi Department of Mechanical Engineering Sharif University of Technology Department of Mechanical Engineering University of California Berkeley Faculty of Engineering Department of Mechanical EngineeringSharif University of Technology Faculty of Engineering Department of Mechanical and Aeronautical EngineeringClarkson University

This study describes a multidimensional 3D/lumped parameter（LP） model which contains appropriate inflow/outflow boundary conditions in order to model the entire human arterial trees. A new extensive LP model of the entire arterial network（48 arteries） was developed including the effect of vessel diameter tapering and the parameterization of resistance, conductor and inductor variables. A computer aided-design（CAD） algorithm was proposed to effciently handle the coupling of two or more 3D models with the LP model, and substantially lessen the coupling processing time. Realistic boundary conditions and Navier-Stokes equations in healthy and stenosed models of carotid artery bifurcation（CAB） were used to investigate the unsteady Newtonian blood flow velocity distribution in the internal carotid artery（ICA）. The present simulation results agree well with previous experimental and numerical studies. The outcomes of a pure LP model and those of the coupled 3D healthy model were found to be nearly the same in both cases. Concerning the various analyzed 3D zones, the stenosis growth in the ICA was not found as a crucial factor in determining the absorbing boundary *** paper demonstrates the advantages of coupling local and systemic models to comprehend physiological diseases of the cardiovascular system.

关键词： Hemodynamic 3D/LP coupling CAD Realis-tic boundary conditions Carotid artery bifurcation Stenosis

多层建筑地震反应对隔震系统参数变化的敏感性分析

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世界地震工程 1992年第4期8卷 64-70页

作者： F.g.Fan g.ahmadi N.Mostaghel I.g.Tadjbakhsh 朱万一

一、前言本文讨论基底隔震多层建筑的地震峰值反应,包括上部结构的峰值加速度和峰值挠度、基底的峰值位移和峰值相对滑移位移反应受隔震系参数变化影响的敏感性。

关键词：多层建筑地震隔震系统参数变化

Model Reference Adaptive Controller for Simultaneous Voltage and Frequency Restoration of Autonomous AC Microgrids

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Journal of Modern Power Systems and Clean Energy 2024年第4期12卷 1194-1202页

作者： Farahnaz ahmadi Yazdan Batmani Hassan Bevrani Department of Electrical Engineering University of KurdistanSanandajIran

In an autonomous droop-based microgrid,the sys-tem voltage and frequency(VaF)are subject to deviations as load *** the existence of various control methods aimed at correcting system frequency deviations at the second-ary control level without any communication network,the chal-lenges associated with these methods and their abilities to simul-taneously restore microgrid VaF have not been fully *** this paper,a multi-input multi-output(MIMO)model ref-erence adaptive controller(MRAC)is proposed to achieve VaF restoration while accurate power sharing among distributed generators(Dgs)is *** proposed MRAC,without any communication network,is designed based on two meth-ods:droop-based and inertia-based *** the microgrid,the suggested design procedure is started by defining a model reference in which the control objectives,such as the desired settling time,the maximum tolerable overshoot,and steady-state error,are ***,a feedback-feedforward con-troller is established,of which the gains are adaptively tuned by some rules derived from the Lyapunov stability *** some simulations in MATLAB/SimPowerSystem Tool-box,the proposed MRAC demonstrates satisfactory perfor-mance.

关键词： AC microgid communication-free secondary control droop-based method inertia-based method model reference adaptive controller(MRAC) simultaneous voltage and frequency restoration

Numerical study of the near-wall vortical structures in particle-laden turbulent flow by a new vortex identification method-Liutex

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Journal of Hydrodynamics 2024年第1期36卷 53-60页

作者： Farid Rousta goodarz ahmadi Bamdad Lessani Chaoqun Liu Department of Mechanical and Aerospace Engineering Clarkson UniversityPotsdamNYUSA Mechanical Engineering and Engineering Science The University of North Carolina at CharlotteNCUSA Department of Mathematics University of Texas at ArlingtonArlingtonTXUSA

This study investigates turbulent particle-laden channel flows using direct numerical simulations employing the Eulerian-Lagrangian method.A two-way coupling approach is adopted to explore the mutual interaction between particles and fluid *** considered cases include flow with particle Stokes number varying from St=2 up to St=100 while maintaining a constant Reynolds number of Reτ=180 across all cases.A novel vortex identification method,Liutex(Rortex),is employed to assess its efficacy in capturing near-wall turbulent coherent structures and their interactions with *** Liutex method provides valuable information on vortex strength and vectors at each location,enabling a detailed examination of the complex interaction between fluid and particulate *** widely acknowledged,the interplay between clockwise and counterclockwise vortices in the near-wall region gives rise to low-speed streaks along the *** low-speed streaks serve as preferential zones for particle concentration,depending upon the particle Stokes *** is shown that the Liutex method can capture these vortices and identify the location of low-speed ***,it is observed that the particle Stokes number(size)significantly affects both the strength of these vortices and the streaky structure exhibited by ***,a quantitative analysis of particle behavior in the near-wall region and the formation of elongated particle lines was carried *** involved examining the average fluid streamwise velocity fluctuations at particle locations,average particle concentration,and the normal velocity of particles for each set of particle Stokes *** investigation reveals the intricate interplay between particles and near-wall structures and the significant influence of particles Stokes *** study contributes to a deeper understanding of turbulent particle-laden channel flow dynamics.

关键词： Turbulent channel flow particle-laden flow direct numerical simulation(DNS) Eulerian-Lagrangian vortex identification turbulence coherent structures Liutex

Special Issue:International Conference on Sustainable Energy Sources,Technologies and Systems 2023(ICSESTS-2023)

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Clean Energy 2024年第3期8卷 136-137页

作者： Ravinder Kumar Mohammad Hossein ahmadi School of Mechanical Engineering Lovely Professional UniversityPhagwra-144411PunjabIndia Faculty of Mechanical Engineering Shahrood University of TechnologyShahroodIran

The Division of Research and Development at Lovely Professional University,Punjab organized the International Conference on Sustainable Energy Sources,Technologies and Systems 2023(ICSESTS-2023),which took place on 3-... 详细信息

关键词： solar energy storage wind energy geothermal hydropower biofuels batteries

Studying the effect of surfactant assisted low-salinity water flooding on clay-rich sandstones

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Petroleum 2024年第2期10卷 306-318页

作者： Saeed Khezerloo-ye Aghdam Alireza Kazemi Mohammad ahmadi Department of Petroleum Engineering Amirkabir University of Technology(AUT)TehranIran Department of Petroleum and Chemical Engineering College of EngineeringSultan Qaboos UniversityMuscatOman

Sandstone reservoirs often contain clay particles that can cause damage and reduce permeability during low-salinity water *** this study,the effect of surfactants on fine migration in clay-rich sandstones and its impact on oil recovery was ***,the impact of surfactants on interparticle forces in fine-matrix,fine-fine,and oil-matrix systems was *** results showed that both CTAB(cetyltrimethyl ammonium bromide)and QS(quillaja saponin)cause EDL compaction,weakening the repulsive ***,SDS(sodium dodecyl sulfate)and TX(triton X-100)do not affect the ***,the effect of surfactants on IFT reduction and wettability alteration was experimentally *** surfactants reduced IFT due to the surface excessive concentration *** wettability alteration experiment illustrated that although QS and CTAB compact EDL around oil and matrix particles leading to attraction force augmentation,they both alter wettability through adsorption on matrix and carboxylic groups present in crude oil,*** aqueous solutions were then injected into various clay-rich sandstone sanpacks,which resulted in increased oil ***,the mechanisms leading to enhanced oil recovery variedby surfactant *** increased recovery by 10%through IFT reduction and wettability alteration,while SDS and TX increased recovery by 12%and 9%,respectively,through wettability alteration and extreme fine *** contrast,partial fine migration in the QS flooding experiment reached a recovery increase of 18%.Permeability trends through experiments were also *** CTAB injection,permeability did not reduce,while QS aqueous solution reduced rock permeability to 5 m *** and TX reduced the magnitude of permeability to 2 m *** conclusion,this study demonstrates that surfactants can effectively improve oil recovery in clay-rich sandstones by altering the interparticle forces,reducing IFT,and changing *** results

关键词： Surfactant flooding Smart water Fine migration Recovery factor

RogRUT: A Hybrid Deep Learning Model for Detecting Power Trapping in Smart grids

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Computers, Materials & Continua 2024年第5期79卷 3175-3192页

作者： Farah Mohammad Saad Al-ahmadi Jalal Al-Muhtadi Center of Excellence in Information Assurance(CoEIA) King Saud UniversityRiyadh11543Saudi Arabia College of Computer&Information Sciences King Saud UniversityRiyadh11543Saudi Arabia

Electricity theft is a widespread non-technical issue that has a negative impact on both power grids and electricity *** hinders the economic growth of utility companies,poses electrical risks,and impacts the high energy costs borne by *** development of smart grids is crucial for the identification of power theft since these systems create enormous amounts of data,including information on client consumption,which may be used to identify electricity theft using machine learning and deep learning ***,there also exist different solutions such as hardware-based solutions to detect electricity theft that may require human resources and expensive ***-based solutions are presented in the literature to identify electricity theft but due to the dimensionality curse,class imbalance issue and improper hyper-parameter tuning of such models lead to poor *** this research,a hybrid deep learning model abbreviated as RogRUT is proposed to detect electricity theft as amalicious and non-malicious *** key steps of the RogRUT are data preprocessing that covers the problem of class imbalance,feature extraction and final theft *** advanced-level models like RoBERTa is used to address the curse of dimensionality issue,the near miss for class imbalance,and transfer learning for *** effectiveness of the RogRUTis evaluated using the dataset fromactual smartmeters.A significant number of simulations demonstrate that,when compared to its competitors,the RogRUT achieves the best classification *** performance evaluation of the proposed model revealed exemplary results across *** accuracy achieved was 88%,with precision at an impressive 86%and recall reaching 84%.The F1-Score,a measure of overall performance,stood at 85%.Furthermore,themodel exhibited a noteworthyMatthew correlation coefficient of 78%and excelled with an area under the curve of 91%.

关键词： Electricity theft smart grid RoBERTa gRU transfer learning

Molecular insights into oil detachment from hydrophobic quartz surfaces in clay-hosted nanopores during steam-surfactant co-injection

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Petroleum Science 2024年第4期21卷 2457-2468页

作者： Ben-Jie-Ming Liu Xuan-Tong Lei Mohammadali ahmadi Zhangxin Chen Department of Chemical and Petroleum Engineering University of Calgary Eastern Institute of Technology

Thermal recovery techniques for producing oil sands have substantial environmental impacts. Surfactants can efficiently improve thermal bitumen recovery and reduce the required amount of steam. Such a technique requires solid knowledge about the interaction mechanism between surfactants, bitumen,water, and rock at the nanoscale level. In particular, oil sands ores have extremely complex mineralogy as they contain many clay minerals(montmorillonite, illite, kaolinite). In this study, molecular dynamics simulation is carried out to elucidate the unclear mechanisms of clay minerals contributing to the bitumen recovery under a steam-anionic surfactant co-injection process. We found that the clay content significantly influenced an oil detachment process from hydrophobic quartz surfaces. Results reveal that the presence of montmorillonite, illite, and the siloxane surface of kaolinite in nanopores can enhance the oil detachment process from the hydrophobic surfaces because surfactant molecules have a stronger tendency to interact with bitumen and quartz. Conversely, the gibbsite surfaces of kaolinite curb the oil detachment process. Through interaction energy analysis, the siloxane surfaces of kaolinite result in the most straightforward oil detachment process. In addition, we found that the clay type presented in nanopores affected the wettability of the quartz surfaces. The quartz surfaces associated with the gibbsite surfaces of kaolinite show the strongest hydrophilicity. By comparing previous experimental findings with the results of molecular dynamics(MD) simulations, we observed consistent wetting characteristics. This alignment serves to validate the reliability of the simulation outcomes. The outcome of this paper makes up for the lack of knowledge of a surfactant-assisted bitumen recovery process and provides insights for further in-situ bitumen production engineering designs.

关键词： Clay minerals Bitumen Contact angle Interaction energy Surfactant Molecular dynamics