کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
7056563 | 1458053 | 2015 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Counter-current motion of a droplet levitated on a liquid film undergoing Marangoni convection
ترجمه فارسی عنوان
حرکت قطره ای روی یک فیلم مایع تحت جابجایی مارنگونی
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کلمات کلیدی
کنسانتره مارانگونی، پدیده های متقابل، انتقال حرارت بین فاز پراکندگی قطره، حرکت ترموکاپیلی، ضریب کشیدن،
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
جریان سیال و فرایندهای انتقال
چکیده انگلیسی
This paper experimentally and analytically investigates the motion of a levitated droplet against the Marangoni flow in an immiscible outer fluid. Based on our earlier experiments, when a droplet is released from a height â¼1.5-4 times its diameter from the liquid surface, it can overcome the impact and stay levitated at the liquid-air interface due to the existence of an air gap between the droplet and the liquid film. Surprisingly, such a levitated droplet, moves toward the heating source against the Marangoni convection. In order to explain this behavior, we propose a simple approach: first, the Marangoni convection inside the thin film is considered without the droplet floating on the surface. By using a level-set method and solving the Navier-Stokes equation, the free surface velocity and deformation are calculated. Then, these quantities are used to solve for droplet velocity and drag coefficient simultaneously using a force balance. In order to compare the simulation results, experiments with levitated water droplets on an immiscible carrier liquid, FC-43, are conducted for various temperature gradients and droplet velocities are measured at different locations using high-speed imaging. The experimental results are in good agreement with the developed theoretical model. For a Reynolds number range of 2-32, it is shown that the drag coefficients are up to 66% higher than those for the fully immersed sphere at the same Reynolds numbers. Finally, a correlation is proposed to calculate the drag coefficient of levitated droplets for various temperature drops across the channel.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Heat and Mass Transfer - Volume 89, October 2015, Pages 345-352
Journal: International Journal of Heat and Mass Transfer - Volume 89, October 2015, Pages 345-352
نویسندگان
Ashkan Davanlou, Ranganathan Kumar,