بررسی اثر میدان مغناطیسی بر جابه‌جایی طبیعی جریان آرام و متلاطم نانوسیال در محفظه‌ ذوزنقه‌ای

نویسندگان

دانشگاه کاشان

چکیده

جریان سیال تحت تاثیر میدان مغناطیسی در خنک‌کاری سامانه‌های الکترونیکی و ترانسفورماتورهای برق و پدیده‌های فیزیکی مثل زمین‌شناسی مطرح می‌باشد. در مطالعه حاضر اثر میدان مغناطیسی بر میدان جریان و انتقال حرارت جابه‌جایی طبیعی نانوسیال آب- اکسیدمس با لحاظ اثر حرکت براونی نانوذرات در محفظه‌ ذوزنقه‌ای برای هر دو رژیم جریان آرام و متلاطم مطالعه شده است. مطالعه برای اعداد رایلی 103 تا 1010، اعداد هارتمن 0 تا 100 و کسر حجمی‌های 0تا 04/0 از نانوذرات انجام شده است. معادلات حاکم با روش حجم محدود و الگوریتم سیمپلر به‌صورت عددی با استفاده از یک برنامه کامپیوتری به زبان فرترن حل شده‌اند. نتایج نشان دادند که با اعمال میدان مغناطیسی و افزایش آن، سرعت جابه‌جایی نانوسیال و قدرت جریان در هر دو رژیم جریان آرام و متلاطم کاهش می‌یابد. از مقایسه خطوط جریان و هم‌دما در رژیم آرام با متلاطم مشخص می‌شود که با توجه به ثابت ماندن قدرت میدان مغناطیسی (عدد هارتمن ثابت) در هر دو رژیم جریان آرام و متلاطم، خطوط جریان و هم‌دما در رژیم متلاطم کمتر تحت تاثیر نیروی لورنتس قرار می‌گیرند. برای هر دو رژیم جریان آرام و متلاطم با زیاد شدن کسر حجمی نانوذرات و افزایش عدد رایلی عدد ناسلت متوسط زیاد می‌شود. همچنین در همه‌ اعداد رایلی و کسرهای حجمی‌ با افزایش عدد هارتمن، عدد ناسلت متوسط کاهش می‌یابد.

کلیدواژه‌ها


عنوان مقاله [English]

Investigation of Laminar and Turbulent of Natural Convection of Nanofluid in a Trapezoidal Enclosure under the Influence of Magnetic Field

نویسندگان [English]

  • alireza aghai
  • hosein khorasani zade
  • ghanbar ali sheikh zade
kashan
چکیده [English]

The flow affected by a magnetic field is applied in cooling electronic devices and voltage transformers and in physical phenomenon such as geology. In this study, the effects of magnetic field on the flow field and heat transfer of Cu-water nanofluid natural convection and by considering the Brownian motion of nanoparticles have been studied in a trapezoidal enclosure. The study has been done for Rayleigh numbers 103 to 1010, Hartmann numbers 0 to 100 and the nanoparticles volume fraction of 0 to 0.04. The governing equations have been solved numerically by use of finite volume method and SIMPLER algorithm. The results showed that by applying the magnetic field and increasing it, the nanofluid convection and the strength of flow decrease and the flow tends toward natural convection and finally toward pure conduction. For all of the Reynolds numbers and volume fractions which are considered, by increasing the Hartmann number, the average Nusselt number decreases.

کلیدواژه‌ها [English]

  • Nanofluid
  • Natural Convection
  • Magnetic Field
  • Hartmann Number
  • Variable Properties
  • Turbulent Flow
  • k-ε Model
  1. Mahian, O., Mahmud, S., and Pop, I. “Analysis of first and second laws of thermodynamics between two isothermal cylinders with relative rotation in the presence of MHD flow”, Int. J. Heat. Mass Transfer, Vol. 55, No. 17, pp. 4808-4816, 2012.##
  2. Kandaswamy, P., Sundari, SM., and Nithyadevi, N. “Magnetoconvection in an enclosure with partially active vertical walls”, Int. J. Heat Mass Transfer, Vol. 51, No. 7, pp. 1946–1954, 2008.##
  3. Pirmohammadi, M., and Ghassemi, M. “Effect of magnetic field on convection heat transfer inside a tilted square enclosure”, Int. Commun. Heat Mass Transfer, Vol. 36, No. 7, pp. 776–780, 2009.##
  4. Sadeghi, S., and Ghasemi, A. “Mixed convection heat transfer of nanofluids B.in an inclined channel under magnetic field”, J. Modarres Mechanical Engineering, Vol. 13, No. 7, pp. 18–31, 2013 (in Persian)##
  5. Malekpor, A., and Ghasemi, B. “Magnetic firld effect on natural convection in a nanofluid filled triangular enclosure”, J. Modarres Mechanical Engineering, Vol. 13, No. 3, pp. 10–21, 2013. (in Persian)##
  6. Basak, T., Roy, S., and Pop, I. “Heat flow analysis for natural convection within trapezoidal enclosures based on heatline concept”, Int. J. Heat. Mass Transfer, Vol. 52, No. 11, pp. 2471–2483, 2009.##
  7. Saleh, H., Roslan, R., and Hashim, I. “Natural convection heat transfer in a nanofluid-filled trapezoidal enclosure”, Int. J. Thermal Science, Vol. 54, No. 3, pp. 194–201, 2011.##
  8. Togun, H., Safaei, M.R., Rad Sadri, S., Kazi, N., Badarudin, A., Hooman, K., and Sadeghinezhad, E. “Numerical simulation of laminar to turbulent nanofluid flow and heat transfer over a backward-facing step”, Applied Mathematics and Computation, Vol. 239, No. 1, pp. 153–170, 2014.##
  9. Ahmeda, M. A., Yusoff, M.Z., Ng, K.C., and Shuaib, N.H. “Numerical investigations on the turbulent forced convection of nanofluids flow in a triangular-corrugated channel”, Case Studies in Thermal Engineering, Vol. 6, No. 1, pp. 212–225, 2015.##

10. Abdellahoum, C., Mataoui, A., and Oztop, H. F. “Comparison of viscosity variation formulations for turbulent flow of Al2O3–water nanofluid over a heated cavity in a duct”, Advanced Powder Technology, Vol. 26, No. 1, pp. 1210-1218, 2015.##

11. Davarnejad, R., and Jamshidzadeh, M. “CFD modeling of heat transfer performance of MgO-water nanofluid under turbulent flow”, Engineering Science and Technology, Int. J., Vol. 18, No. 1, pp. 536-542.##

12. Abdellahoum, C., Mataoui, A., Abu-Hamdeh, N., and Oztop, H. F. “Effects of different models of thermal conductivity on turbulent nanofluid flow through rectangular cavity in duct”, J. Molecular Liquids, Vol. 212, No. 9, pp. 915–921, 2015.##

13. Choudhary, R., and Subudhi, S. “Aspect ratio dependence of turbulent natural convection in Al2O3/water nanofluids”, Applied Thermal Engineering, Vol. 108, No. 9, pp. 1095–1104, 2016.##

14. Siavashi, M., and Jamali, M. “Heat transfer and entropy generation analysis of turbulent flow of TiO2-water nanofluid inside annuli with different radius ratios using two-phase mixture model”, Applied Thermal Engineering, Vol. 100, No. 1, pp. 1149-1160, 2016.##

15.  Ghodsinezhad, H., Sharifpur, M., and Meyer, J. P. “Experimental investigation on cavity flow natural convection of Al2O3–water nanofluids”, Int. Commun. Heat. Mass Transfer, Vol. 76, No. 1, 1120-1129, 2016.##

16. Mosayebidorcheha, S., Sheikholeslami, M., Hatamid, M., and Ganji, D.D. “Analysis of turbulent MHD Couette nanofluid flow and heat transfer using hybrid DTM–FDM”, Particuology, Vol. 13, No. 1, pp. 20-27, 2016.##

17. Launder, B. E., and Spalding, D. B. “Lectures in Mathematical Models of Turbulence”, Academic Press, London, England, 1972.##

18. Mohamad, A. A., and Viskanta, R. “Modeling of Turbulent Buoyant Flow and Heat Transfer in Liquid Metals”, Int. J. Heat Mass Transfer, Vol. 36, No. 11, pp. 2815-2826, 1993.##

19. Brinkman, H.C. “The viscosity of concentrated suspensions and solution”, The Journal of Chemical Physics, Vol. 20, No. 9, 571–581, 1952.##

20. Maxwell-Garnett, J.C. “Colours in metal glasses and in metallic films, Philos”, Trans. Roy. Soc. A, Vol. 203, No. 1, pp. 385-420, 1904.##

21. Koo, J., and Kleinstreuer, C. “A new thermal conductivity model for nanofluids”, J. Nanoparticle Research, Vol. 6, No. 9, pp. 577–588, 2004.##

22. Ghasemi, B., Aminossadati, S.M., and Raisi, A. “Magnetic field effect on natural convection in a nanofluid-filled square enclosure”, Int. J. Thermal Sciences, Vol. 50, No. 9, pp. 1748-1756, 2013.##

23. Bohn, M.S., Kirkpatrick, A.T., and Olson, D .A. “Experimental Study of Three Dimensional Natural Confection High-Rawleiah Number”, J. Heat Transfer, Vol. 106, No. 9, pp. 339-345, 1984.##