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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Challenges in Nano and Micro Scale Science and Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Variable properties nanofluid,Trapezoidal microchannel,Trapezoidal heat sink,Inlet/outlet arrangements,KKL Brownian motion model
- چکیده:
- چکیده انگلیسی: Nowadays, microchannels as closed circuits channels for fluid flow and heat removal are an integral part of the silicon-based electronic microsystems. Most of previous numerical studies on microchannel heat sinks (MCHS) have been performed for a two-dimensional domain using constant properties of the working fluid. In this study, laminar fluid flow and heat transfer of variable properties Al2O3-water nanofluid in a trapezoidal MCHS, consisted of five trapezoidal microchannels have been studied. The three dimensional solution domains include the whole flow field and the complete MCHS solid parts. Four inlet/outlet arrangements, three pressure drops of 5, 10 and 15 kPa and nanoparticles volume fractions between 0 and 4% are assumed and the effects of these arrangements, properties variations and the Brownian motion on the heat sink performance quantified. The results indicate that the A-type heat sink, for which the inlet and outlet are placed horizontally at the center of the north and the south walls, has a better heat transfer performance, smaller thermal resistance and provides more uniform substrate temperature distribution. Temperature-dependent properties increases the heat transfer between 2.7% and 3.39%, decreases the thermal resistance between 3.49% and 6.29 % and decreases the ratio of difference between the maximum and minimum substrate temperatures to the heat flux between 3.3% and 7.19%. Presence of the Brownian motion showed a similar trend but with a slighter importance.
- انتشار مقاله: 02-07-1395
- نویسندگان: Hossien Khorasanizadeh,Mojtaba Seperhnia
- مشاهده
- جایگاه : پژوهشی
- مجله: Challenges in Nano and Micro Scale Science and Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Electroosmotic flow,KEYWORDS lattice Boltzmann,slip velocity boundary conditions
- چکیده:
- چکیده انگلیسی: The aim of the present work is to analyze the accuracy and to extend the capability of lattice Boltzmann method in slip EOF; a phenomenon which was previously studied by molecular dynamics and less considered by LBM. At the present work, a numerical experiment on boundary conditions of slip velocity is performed and the proportionality of slip with shear stress in electroosmotic pump is proved. Results show that LBM can capture the slip length in EOF with liquid operating fluid. Implementing slip velocity at the walls of a microchannel, the electroosmotic flow with adverse pressure gradient over a hydrophobic surface is investigated in view of mixing reduction. The fluid flow is assumed to be laminar, steady and viscous. Slip at the channel boundaries will decelerate the development process of the flow. Unlike no-slip condition, transverse change in velocity magnitude near the walls decreases and also more resistant pressure is required to create reverse centerline velocity; so mixing probability and performance of EOF pump can alter considerably.
- انتشار مقاله: 21-03-1397
- نویسندگان: Ahmad REza Rahmati,Hossien Khorasanizadeh,Mohammad Reza Arabyarmohammadi
- مشاهده