بررسی اثر گرانش بر جابجایی توام یک میکروجریان با استفاده از روش شبکه بولتزمن

نویسندگان

1 دانشگاه آزاد اسلامی واحد نجف‌آباد

2 دانشگاه آزاد اسلامی واحد خمینی شهر

چکیده

هدف این مقاله مطالعه اثرات گرانش بر انتقال حرارت جابجایی توام در یک میکروکانال با استفاده از روش شبکه بولتزمن است. به این منظور، معادلات شرایط‌مرزی هیدرودینامیکی نیز باید اصلاح شوند. سیال سرد وارد میکروکانال شده و بعد از خنک سازی دیوارهای گرم، از آن خارج می گردد. محاسبات برای محدوده گسترده ای از عدد نادسن (Kn) انجام می شود. نتایج در قالب خطوط جریان و همدما، تغییرات طولی ضریب اصطکاک، عدد ناسلت، سرعت لغزشی، پرش دمایی و پروفیل های دما و سرعت در مقاطع مختلف ارائه می گردند. مشاهده شد که روش شبکه بولتزمن را می توان برای شبیه سازی جابجایی توام در یک میکروکانال با دقت خوبی بکار برد و همچنین می توان ادعا نمود که اثرات نیروهای شناوری برروی خواص حرکتی به ازای Kn0.05، این اثرات را می توان نادیده گرفت. علاوه براین، دیده شد که نیروهای شناوری یک سلول چرخشی در جریان داخل میکروکانال ایجاد می کنند که منجر به تولید سرعت لغزش منفی در Kn0.005 می شود.

کلیدواژه‌ها


عنوان مقاله [English]

THE INFLUENCE OF GRAVITY ON A MICROFLUIDIC MIXED CONVECTION BY APPLYING LATTICE BOLTZMANN METHOD

نویسندگان [English]

  • arash Karimipour 1
  • mohammad Akbari 1
  • davood Toghraie 2
1 university
2 university
چکیده [English]

In this article the effects of gravity on the mixed convection of a microflow is studied numerically by using lattice Boltzmann method (LBM). To do this, the hydrodynamic boundary condition equations should also be modified. The cold fluid enters to the microchannel and leaves it after cooling its hot walls. Calculations are provided for a wide range of Knudsen number (Kn). The results are presented as the isotherms and streamlines, the values of slip velocity and temperature jump and the local and global profiles of velocity, temperature and Nusselt number. It is observed that LBM is able to simulate the mixed convection in a microchannel appropriately. It is claimed that the effects of buoyancy forces are important for Kn0.05 they can be ignored. Moreover, the buoyancy forces make a rotational cell in the microchannel flow which generates the negative slip velocity at Kn=0.005.

کلیدواژه‌ها [English]

  • Knudsen number
  • LBM
  • Microchannel
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