شبیه سازی جریان نانوسیال در عدد رینولدز پایین دریک میکروکانال با انبساط ناگهانی یک طرفه تحت اثر میدان مغناطیسی

نوع مقاله : مقاله پژوهشی

نویسندگان

• فروزان مرادی
• سید پدرام پورنادری

گروه مهندسی مکانیک، دانشکده مهندسی، دانشگاه یاسوج، یاسوج.

10.22067/jacsm.2023.79298.1143

چکیده

در این مطالعه، تأثیر میدان مغناطیسی بر هیدرودینامیک و انتقال حرارت جریان آرام نانوسیال در یک میکروکانال همراه با انبساط ناگهانی یک­طرفه در عدد رینولدز پایین بررسی می­شود. معادلات حاکم شامل معادلات بقای جرم، مومنتوم و انرژی با توسعه یک کد به زبان برنامه نویسی فرترن به روش تفاضل محدود بر روی یک شبکه جابه‌جا شده گسسته­سازی و حل می­شوند. نتایج  شبیه­سازی نشان می­دهد که در عدد رینولدز پایین، گردابه­ای بعد از پله تشکیل نمی­گردد. در حضور میدان مغناطیسی، ضریب اصطکاک با افزایش  کسر‌حجمی کاهش می­یابد. در کسرحجمی 4 درصد، این کاهش در مقایسه با آب خالص در اعداد هارتمن  20 و 40 به‌ترتیب 25 درصد و 18 درصد است. با اعمال میدان مغناطیسی ضریب اصطکاک افزایش می­یابد. برای نانوسیال با غلظت 4 درصد، افزایش ضریب اصطکاک متوسط در مقایسه با آب در اعداد هارتمن 20 و 40 به‌ترتیب 176 و 337 درصد می­باشد. در عدد رینولدز پایین، تأثیر میدان مغناطیسی بر روی عدد ناسلت ناچیز می­باشد. با افزایش  کسر‌حجمی عدد ناسلت کاهش می­یابد. در  کسر‌حجمی  4 درصد، تقریبا 12 درصد کاهش در عدد ناسلت در مقایسه با آب مشاهده می­گردد. بررسی معیار ارزیابی عملکرد نشان می­دهد که اعمال میدان مغناطیسی، منجر به بهبود عملکرد سیستم می­گردد. در عدد هارتمن 20 و  کسر‌حجمی 4 درصد، حدود 11 درصد افزایش در ضریب عملکرد نسبت حالت بدون میدان مشاهده می­شود.

کلیدواژه‌ها

• نانوسیال
• میکروکانال
• انبساط ناگهانی
• میدان مغناطیسی
• عدد رینولدز پایین

موضوعات

• مکانیک سیالات

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عنوان مقاله [English]

Simulation of nanofluid flow at low Reynolds number in a microchannel with one-sided sudden expansion under the effect of a magnetic field

نویسندگان [English]

• Foroozan Moradi
• Pedram Pournaderi

Department of Mechanical Engineering, Faculty of Engineering, Yasouj University, Yasouj, Iran.

چکیده [English]

In this study, the magnetic field effect on the hydrodynamics and heat transfer of the laminar flow of a nanofluid in a microchannel with one-sided sudden expansion at a low Reynolds number is investigated. The governing equations including mass, momentum, and energy conservation equations are discretized and solved on a staggered grid using the finite difference method by developing a Fortran code. The simulation results show that at a low Reynolds number, no vortex is formed after the step. In the presence of a magnetic field, the friction coefficient decreases with volume fraction. At a volume fraction of 0.04, this reduction in comparison with water at Hartmann numbers of 20 and 40 is 25 and 18 percent, respectively. By applying the magnetic field, the friction factor increases. For nanofluid with a volume fraction of 0.04, the enhancement of average friction factor in comparison with water at Hartmann numbers of 20 and 40 is 176 and 337 percent, respectively. At a low Reynolds number, the magnetic field effect on the Nusselt number is negligible. The Nusselt number decreases with volume fraction. At a volume fraction of 0.04, a reduction of about 12 percent is observed in the Nusselt number in comparison with water. Examining the performance evaluation criteria shows that applying a magnetic field improves the system's performance. At a Hartmann number of 20 and volume fraction of 0.04, an enhancement of about 11 percent in performance coefficient is observed in comparison with the case that the magnetic field is absent.

کلیدواژه‌ها [English]

• Nanofluid
• Microchannel
• Sudden expansion
• Magnetic field
• Low Reynolds number

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