اثر میدان مغناطیسی بر جابجایی آزاد سیال غیرنیوتنی در محفظه مربعی با چشمه حرارتی مرکزی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه شهرکرد، شهرکرد

2 دانشگاه شهرکرد*دانشکده فنی ومهندسی

چکیده

در این مطالعه جریان لایه‌ای تراکم ناپذیر سیال غیرنیوتنی با چشمه گرمایی مرکزی در یک محفظه برای حالت‌های بدون میدان مغناطیسی و اعمال میدان مغناطیسی یکنواخت تحت زاویه‌ای مشخص، بررسی شده است. معادلات حاکم به روش اختلاف محدود بر مبنای حجم کنترل گسسته‌سازی شده‌اند و میدان حل مسئله با استفاده از شبکه یکنواخت شبکه‌بندی شده است. این مسئله برای حالت پایدار با فرمول‌بندی ضمنی و با الگوریتم سیمپل حل شده است. در مطالعه حاضر تأثیر غیرنیوتنی بودن سیال با مدل قانون توانی با وجود میدان مغناطیسی یکنواخت، برای مقادیر شاخص توانی ۴/۱ ,۱ ,۷۵/۰  بررسی شده و نتایج به دست آمده با شرایط عدم وجود میدان مقایسه شد. با توجه به نتایج حاصل شده، می‌توان بیان کرد که اعمال میدان مغناطیسی برای شاخص‌های مختلف سیال، در رایلی‌های متفاوت رفتار یکسانی را نشان نمی‌دهد و با اعمال میدان مغناطیسی، جابجایی جریان در محفظه تقلیل می‌یابد. همچنین می‌توان گفت که با اعمال میدان مغناطیسی در محدوده  برای سیال مدل قانون توانی، افزایش عدد رایلی باعث کاهش نوسلت متوسط و برای ۱n˂ باعث افزایش نوسلت متوسط خواهد شد. برای شاخص ۱n˃ با افزایش رایلی در حضور یک میدان مغناطیسی ثابت، می‌توان جابجایی آزاد را تضعیف نمود در حالیکه این روند برای ۱n˂ با کاهش عدد رایلی رخ می‌دهد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Effects of Magnetic Field on Natural Convection of Non-Newtonian Fluid in a Square Enclosure with a Central Heat Source

نویسندگان [English]

  • Akram Jahanbakhshi 1
  • Afshin Ahmadi Nadooshan 2
1 Shahrekord University, Shahrekord
2 Mechanical Engineering Department, Shahrekord University, Shahrekord
چکیده [English]

In this study, the incompressible laminar flow of non-Newtonian fluid is studied in a cavity with a central heat source under a uniform inclined magnetic field. The governing equations are converted into nonlinear ordinary differential equations using similarity transformations and solved using finite difference based numerical methods. In the current study, the effect of non-Newtonian power-law fluid is investigated for power-law indices of 0.75, 1 and 1.4. The results are compared with the ones in which the magnetic field is not applied. It is found that the implementation of a magnetic field for different fluid indices in different Rayleigh numbers does not show similar behaviors and the results show that the magnetic field affects the convection flow, leading to a reduction in it. Also can be said that with the implementation of a magnetic field in the range of indices n ≥ 1 for power-law model fluid, increased Rayleigh number leads to reduced average Nusselt number and for n ˂ 1, the average Nusselt increases. For n ˂ 1, with increased Rayleigh number in the presence of a fixed magnetic field, free convection can be weakened while this trend for n ˂ 1 occurs with reduced Rayleigh number.

کلیدواژه‌ها [English]

  • Non- Newtonian fluid
  • Power-law model
  • magnetic field
  • Natural convection
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