بررسی جریان سه بعدی جابجایی آزاد نانو‌سیال تحت تاثیر میدان مغناطیسی با استفاده از روش شبکه بولتزمن بر پایه مدل زمان آرامش چندگانه دوتایی

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشکده فنی و مهندسی، دانشگاه بجنورد، بجنورد، ایران

چکیده

در این مقاله اثر میدان مغناطیسی بر روی جریان جابجایی طبیعی سه بعدی نانوسیال مس/آب داخل یک حفره مکعبی با استفاده از روش شبکه بولتزمن بر پایه مدل جدید زمان آرامش چندگانه دوتایی مورد بررسی قرار گرفت. به منظور اعمال مدل زمان آرامش چندگانه دوتایی شبکه D3Q19 برای حل معادله جریان و شبکه D3Q7 نیز برای حل میدان دما استفاده شد و تاثیر اعداد گراشف(Gr=1e3-1e5) و هارتمن (Ha=0-100) برای میزان نسبت حجمی‌های نانوذره متفاوت (12%-0=φ) مورد بررسی قرار گرفت. نتایج برای صفحات و خطوط مختلف مکعب نشان داده شد و با توجه به دقت نتایج بدست آمده، روش عددی استفاده شده روشی مناسب برای حل جریان های پیچیده ارزیابی شد. همچنین با افزایش عدد هارتمن در حالت سیال بدون نانوذره مقدار انتقال حرارت کاهش یافت به‌طوری که بیشترین مقدار کاهش عدد ناسلت با افزایش عدد هارتمن از صفر تا 100 برابر 71% برای عدد گراشف 1e4مشاهده شد. در صورتی که با افزایش عدد گراشف و نسبت حجمی نانوذره میزان انتقال حرارت برای تمام اعداد هارتمن افزایش یافت و بیشترین میزان تاثیر نانو ذره در عدد گراشف 1e4 و عدد هارتمن 50 مشاهده گردید به طوری که با افزایش 12% حجمی نانوذره عدد ناسلت به میزان 43% افزایش یافت.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Investigation of 3-D Nanofluid Natural Convection in Presence of Magnetic Field using Double MRT Lattice Boltzmann method

نویسندگان [English]

  • Hasan Sajjadi
  • Amin Amiri Delouei
Department of Mechanical Engineering, University of Bojnord
چکیده [English]

In this work numerical simulation of magneto hydrodynamics (MHD) natural convection in a three dimensional square cavity has been considered by new means of the Lattice Boltzmann method with double Multi-Relaxation-Time (MRT) model utilizing cu/water nanofluids. D3Q19 and D3Q7 models have been used to solve the momentum and energy equations, respectively and the effect of different Grashof numbers (Gr=1e3 _1e5) and various Hartmann numbers (Ha=0-100) for volumetric fraction of the nanoparticles between 0 and 12% have been investigated. The results have been shown at different planes and lines of the 3-D enclosure and based on the results the double MRT-LBM method is a proper method for simulating the complex 3-D flows. Also, the results show that augmentation of the Hartmann number decreases the heat transfer for base fluid and the maximum reduction of Nusselt number with increasing Hartmann number from 0 to 100 has been observed as 71% for Gr=1e4. While increasing the Grashof number and volumetric fraction of the nanoparticles enhance the heat transfer rate for all Hartmann number. The highest effect of nanoparticle is obtained at Gr=1e4 and Ha=50 as with increasing 12% of volumetric fraction of the nanoparticles Nusselt number enhances 43% .

کلیدواژه‌ها [English]

  • Lattice Boltzmann method
  • Double MRT
  • Nanofluid
  • MHD
  • Natural convection

مراجع

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نشریه مهندسی مکانیک امیرکبیر
دوره 51، شماره 4
مهر و آبان 1398
صفحه 111-120

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