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Phase-Field Lattice-Boltzmann Study for α-Mg Dendrite Growth of Mg-5wt%Zn Alloy with forced convection

Acta Metallurgica Sinica(English Letters) 2023年第11期36卷 1791-1804页

作者： Wei-Peng Chen Hua Hou Yun-Tao Zhang Wei Liu Yu-Hong Zhao School of Materials Science and Engineering Collaborative Innovation Center of Ministry of Education and Shanxi Province for High-Performance Al/Mg Alloy MaterialsNorth University of ChinaTaiyuan030051China Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology BeijingBeijing100083China School of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan030024China Institute of Materials Intelligent Technology Liaoning Academy of MaterialsShenyang110004China

Melt flow can significantly change the transport of heat and solute,dendrite growth.In this work,a phase-field lattice-Boltzmann model was developed to studyα-Mg dendrite growth of Mg-5wt%Zn alloy with forced convection.Results show that the existence of forced convection and overlap of thermal and solute fields makes thermal and solute fields distribution nonuniform.Thus,the symmetry of dendrite morphology is destroyed.The solid temperature and concentration of the downstream dendrite tip front with forced convection are higher than that without forced convection,while the concentration of the upstream dendrite tip front is lower.The solute transport through melt flow will be hindered by developed sidebranching.With flow velocity increase,the upstream temperature gradient and thickness of the downstream solute enrichment layer increase gradually,while the downstream temperature gradient and thickness of the upstream solute enrichment layer decrease gradually.Meanwhile,the upstream dendrite tip velocity will increase gradually,while the downstream dendrite tip velocity will decrease at first and then unchanged.This study is helpful to establish the relationship betweenα-Mg dendrite growth and melt flow,which is beneficial to understand the role of melt flow on dendrite morphologies.

关键词： Dendrite growth Mg-Zn alloy forced convection Phase-field method Lattice-Boltzmann method

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forced convection Heat Transfer in Porous Structure: Effect of Morphology on Pressure Drop and Heat Transfer Coefficient

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Journal of Thermal Science 2021年第2期30卷 363-393页

作者： ZHAO Jiafei SUN Mingrui ZHANG Lunxiang HU Chengzhi TANG Dawei YANG Lei SONG Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of TechnologyDalian 116023China

A light-weight structure with sufficient mechanical strength and heat transfer performance is increasingly required for some thermal management issues.The porous structure with the skeleton supporting the ambient stress and the pores holding the flowing fluid is considered very promising,attracting significant scientific and industrial interest over the past few decades.However,due to complicated morphology of the porous matrices and thereby various performance of the pressure drop and heat transfer coefficients (HTC),the comprehensive comparison and evaluation between different structures are largely unclear.In this work,recent researches on the efforts of forced convection heat transfer in light-weight porous structure are reviewed;special interest is placed in the open-cell foam,lattice-frame,structured packed bed,and wire-woven structures.Their experimental apparatus,morphological of the porous structures,effect of morphology on pressure drop and HTC,and further applications are discussed.The new method which measure morphology accurately should be paid more attention to develop more accuracy correlation.Also,the most research focused on low Reynolds number and existing structure,while very few researchers investigated the property of forced convection heat transfer in high velocity region and developed new porous structure.

关键词： forced convection heat transfer heat transfer coefficient pressure drop morphological characteristics porous structure

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A CA-LBM model for simulating dendrite growth with forced convection

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Journal of Iron and Steel Research(International) 2021年第8期28卷 997-1008页

作者： Xiang-ning Meng Lei Cui Yi-han Shi Miao-yong Zhu Key Laboratory for Ecological Metallurgy of Multi-Metallic Ores Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina

A two-dimensional coupled model of the cellular automaton(CA)and the lattice Boltzmann method(LBM)was developed to simulate the solute dendrite growth of Fe-C-Mn-S alloy in the presence of forced convection.The model describes the transport phenomenon by the evolution of moving pseudo-particles distribution functions and utilizes the LBM to solve fluid flow and solute transport under forced convection numerically.Based on the solute field calculated by the CA technique,the dynamics of dendrite growth were determined by the previously proposed local solute balance method.The accuracy of the forced convection dendrite growth model was verified by comparing the CA-LBM model with Lipton-Glicksman-Kurz analytical model.It is revealed that the dendrite symmetry structure is destroyed compared to free diffusion,and the upstream arm is more developed than the downstream arm of the dendrite.The enriched solute segregates more at the downstream side than at the upstream side of the dendrite.The length of the upstream dendrite arm increases firstly and then becomes stable with the increase in the flow velocity,the dendrite necking is restrained,and the vertical dendrite arm becomes longer.

关键词： Two-dimensional coupled model Cellular automaton Lattice Boltzmann method Dendrite growth forced convection

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Effect of Magnetic Field on forced convection between Two Nanofluid Laminar Flows in a Channel

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Chinese Journal of Mechanical Engineering 2016年第6期29卷 1235-1243页

作者： Afrasiab Raisi Ahmad Qanbary Engineering Faculty Shahrekord University

This paper provides a numerical study of forced convection between hot and cold nanofluid laminar flows that are separated by a thin membrane, in a horizontal channel. Outer surface of channels＇ walls are thermally insulated and divide into two parts; namely NMP and MP. NMP is the channel＇s wall from the entrance section to the middle section of channel that is not influenced by magnetic field. MP is the channel＇s wall from the middle section to the exit section of channel which is influenced by a uniform-strength transverse magnetic field. The governing equations for both hot and cold flows are solved together using the SIMPLE algorithm. The effects of pertinent parameters, such as Reynolds number （10 ≤ Re ≤500）, Hartman number （0 ≤Ha ≤60） and the solid volume fraction of copper nano-particles （0≤φ≤0.05）, are studied. The results are reported in terms of streamlines, isotherms, velocity and temperature profiles and local and average Nusselt number. The results of the numerical simulation indicate that the increase in Reynolds number and the solid volume fraction lead to increase in Nusselt number. Meanwhile, the results also show that the rate of heat transfer between the flows increases as the Hartmann number increases, especially at higher values of the Reynolds number.

关键词： magnetic field forced convection nanofluid membrane channel

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Entropy generation analysis of thermally developing forced convection in fluid-saturated porous medium

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Applied Mathematics and Mechanics(English Edition) 2008年第2期29卷 229-237页

作者： K.Hooman A.Ejlali F.Hooman School of Engineering The University of QueenslandBrisbaneAustralia Fix Equipment Lead Engineer Namavaran Delvar Engineering and Construction CompanyTehranIran Chemical Engineering Department Sharif University of TechnologyTehranIran

Entropy generation for thermally developing forced convection in a porous medium bounded by two isothermal parallel plates is investigated analytically on the basis of the Darcy flow model where the viscous dissipation effects had also been taken into account. A parametric study showed that decreasing the group parameter and the Peclet number increases the entropy generation while for the Brinkman number the converse is true. Heatline visualization technique is applied with an emphasis on the Br 〈 0 case where there is somewhere that heat transfer changes direction at some streamwise location to the wall instead of its original direction, i.e., from the wall.

关键词： entropy generation porous media heatline energy flux vectors forced convection

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Experimentation of a forced convection Solar Dryer for Drying Sweet Potatoes at the Higher Institute of Technology of Mamou-Guinea

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World Journal of Engineering and Technology 2023年第3期11卷 536-548页

作者： Ansoumane Sakouvogui Thierno Amadou Barry Adama Moussa Sakho Mamby Keita Energy Department Higher Institute of Technology of Mamou Mamou Guinea Department of Chemistry Laboratory Techniques Higher Institute of Technology of Mamou Mamou Guinea Department of Physics Faculty of Sciences Gamal Abdel Nasser University Conakry Guinea

This study was carried out at the Mamou Higher Institute of Technology during the period from March 10 to April 15, 2022, with the aim of designing and testing a solar dryer with forced convection by drying potatoes. The dryer was designed using local materials. Its main geometric parameters are: 1) height of the drying chamber (90 cm), 2) length of the drying chamber (50 cm), 3) width of the drying chamber (43 cm), 4) surface of the racks (0.1806 m2), 5) surface of the heat accumulator (0.2537 m2). The experiment focused on the vacuum test of the dryer for two days and that of the drying of the sweet potato for three days from 8:30 a.m. to 5:30 p.m. The average vacuum test temperature values of the three environments are respectively accumulator (43°C), dryer chamber (41°C) and ambient environment (34°C). Four kilograms (4 kg) of boiled sweet potato were dried. The average temperatures in the accumulator and in the drying chamber during the three days of drying are respectively 33°C and 39°C. The final mass of the dried product is 1.2 kg, with a quantity of water extracted of 2 liters or 63% of the initial mass of the product. The average drying rate is 0.074 kg/h. The drying kinetics showed a decreasing rate in the absence of the heating period and the constant rate period.

关键词： Experimentation Temperature Accumulator forced convection Solar Dryer Sweet Potato

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Influence of Prandtl Number on Thin Film Condensation in forced convection in an Inclined Wall Covered with a Porous Material

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Advances in Materials Physics and Chemistry 2022年第6期12卷 125-140页

作者： Goumbo Ndiaye Momath Ndiaye Vincent Sambou Pape Tamsir Ndiaye Madialène Sène Cheikh Mbow The Water Energy Environment and Industrial Processes Laboratory of the Polytech Higher School Cheikh Anta Diop University Dakar Senegal Laboratory of Fluids Mechanics and Transfers Faculty of Sciences and Technologies Cheikh Anta Diop University Dakar Senegal Department of the Ufr Hydraulics Rural Engineering Machinery and Renewable Energy University of Sine Saloum Elhadji Ibrahima NIASS Kaolack Senegal

The numerical study of thin film type condensation in forced convection of a saturated pure vapor in an inclined wall covered with a porous material is presented. The generalized Darcy-Brinkman-Forchheimer (DBF) model is used to describe the flow in the porous medium while the classical boundary layer equations have been exploited in the case of a pure liquid. The dimensionless equations are solved by an implicit finite difference method and the iterative Gauss-Seidel method. The objective of this study is to examine the influence of the Prandtl number on the hydrodynamic and thermal fields but also on the local Nusselt number and on the boundary layer thickness. For Pr ≤ 0.7 (low) the velocity and the longitudinal temperature increase with the Prandtl number. On the other hand, when Pr ≥ 2 (high) the Prandtl number no longer influences the velocity and the longitudinal temperature. The local Nusselt number increases as the Prandtl number increases and the thickness of the hydrodynamic boundary layer increases as the Prandtl number decreases.

关键词： Condensation Thin Film forced convection Inclined Porous Wall Generalized Darcy-Brinkman-Forchheimer Model Prandtl Number

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EFFECTS OF VISCOUS DISSIPATION ON THERMALLY DEVELOPING forced convection IN A POROUS SATURATED CIRCULAR TUBE WITH AN ISOFLUX WALL

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Applied Mathematics and Mechanics(English Edition) 2006年第5期27卷 617-626页

作者： Kamel Hooman Alireza Pourshaghaghy Arash Ejlali Mechanical Engineering Department Bushehr Engineering FacultyPersian Gulf UniversityBushehrIran Mechanical Engineering Department Faculty of EngineeringUniversity of TehranTehranIran Legal and Contracts Petropars Co.TehranIran

The viscous dissipation effect on forced convection in a porous saturated circular tube with an isoflux wall is investigated on the basis of the Brinkman flow model. For the thermally developing region, a numerical study is reported while a perturbation analysis is presented to find expressions for the temperature profile and the Nusselt number for the fully developed region. The fully developed Nusselt number found by numerical solution for the developing region is compared with that of asymptotic analysis and a good degree of agreement is observed.

关键词： forced convection viscous dissipation Brinkman model Darcy number Nusselt number

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Quantitative Visualization of the Thermal Boundary Layer of forced convection on a Heated or Cooled Flat Plate with a 30°Leading Edge Using a Mach-Zehnder Interferometer

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Journal of Flow Control, Measurement & Visualization 2022年第4期10卷 99-116页

作者： Jun Liu Atsuki Komiya Tochigi R&D Center Keihin Corporation Tochigi Japan Institute of Fluid Science Tohoku University Sendai Japan

This study focuses on the experimental measurements of the heat transfer coefficient over a flat plate with a 30° leading edge. Under forced convection by a hot/cold air and flow over a cooled/heated flat plate, the thermal boundary layer and its thickness are quantitatively visualized and measured using a Mach-Zehnder interferometer. In addition, the variation in the local heat transfer coefficient is evaluated experimentally with respect to the air flow velocity and temperature. Differences within the heat transfer performance between the plates are confirmed and discussed. As a result, the average heat transfer performance is about the same for the heated plate and the cooled plate under all air velocity conditions. This contrasts with the theoretical prediction in the case of low air velocity, the reason considered was that the buoyancy at the 30° leading edge blocked air from flowing across the surface of the plate.

关键词： Thermal Boundary Layer forced convection Heat Transfer Coefficient Visualization Mach-Zehnder Interferometer

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Study of forced convection Heat Transfer of Supercritical CO_(2) in a Horizontal Channel by Lattice Boltzmann Method

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Advances in Applied Mathematics and Mechanics 2010年第5期2卷 564-572页

作者： Xiaodong Niu Hiroshi Yamaguchi Yuhiro Iwamoto Xinrong Zhang Mingjun Li Yuhiro Iwamoto Department of Mechanical Engineering Doshisha UniversityKyo-Tanabe-ShiKyoto 610-0321Japan Department of Energy and Resources Engineering College of EngineeringPeking UniversityBeijing 100871P.R.China Department of Mechanical Engineering Xiangtan UniversityHunan 411105P.R.China

The problem of forced convection heat transfer of supercritical CO_(2) in a horizontal channel is investigated numerically by a lattice Boltzmann method.This study is stimulated by our recent experimental findings on solar collectors using supercritical CO_(2) as a working fluid,which can achieve the collector efficiency high up to 70%.To deeply understand the heat transfer characteristics of supercritical CO_(2) and provide a theoretical guidance for improving our current experimental system,in present study several typical experimental flow conditions are simulated.In particular,the work focuses on the convective heat transfer characteristics of supercritical CO_(2) flowing in a horizontal channel with mediate Reynolds numbers ranging from 210 to 840 and constant heat fluxes from 400.0 to 800.0 W/m^(2).The simulations show that the heat transfer increases with heat flux and decreases with Reynolds number.Furthermore,the mechanisms of heat transfer enhancement of supercritical CO_(2) fluid are identified.

关键词： forced convection supercritical CO_(2) lattice Boltzmann method

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