International Scientific Journal

Thermal Science - Online First

online first only

Numerical study of turbulent natural convection of nanofluids in differentially heated rectangular cavities

In this work we study numerically the turbulent natural convection of nanofluids (water + AL2O3 / NTC / Cu) in rectangular cavities differentially heated. The objective is to compare the effect of the macrostructural aspect of the rectangular cavity and the effect of the types of nanofluids studied on the thermal exchange by turbulent natural convection in this type of geometry. Therefore, we have numerically treated the cases of these three nanofluids, for different particles volume fractions (0≤ Ф ≤ 0.06) and for different form ratios of the rectangular cavity. The standard κ - ε turbulence model is used to take into account the effects of turbulence. The governing equations are discretized by the finite volume method using the power law scheme which offers a good stability characteristic in this type of flow. The results are presented in the form of streamlines and isothermal lines. The variation of the average Nusselt number is calculated as a function of the types of nanoparticles, of theirs particles volume fractions Ф, for different form ratios of the cavity and for different Rayleigh numbers. The results show that the average Nusselt number is greater as the form ratio is large and that the effect of the use of carbon nanotubes (CNT) in suspension in a water prevails for voluminal fractions and large Rayleigh numbers.
PAPER REVISED: 2019-09-19
PAPER ACCEPTED: 2019-11-20
  1. S.U.S.Choi, enhancing thermal conductivity of fluids with nanoparticules, developments and applications of Non -Newtonian flows. FED-Vol.231/MD-Vol.66 (1995) 99-105.
  2. S.M.S. Murshed, K.C. Leong, and C. Yang. Thermal conductivity of nanoparticle suspensions. International Journal of thermal science, Singapore (2007).
  3. F. Ehsan F. Mousa, S. Kurosh, N. Hasan, Lattice Boltzmann simulation of natural convection heat transfer in nanofluids, Int. J. Thermal Sciences, 52 (2012), 137-144.
  4. M. Anish et al. Experimental study of heat transfer through cooling water circuit in a reactor vault by using Al2O3 Nanofluid. Thermal Sciences (2018), Vol. 22, No. 2, pp. 1149-1161.
  5. S. Morsli and al. Influence of aspect ratio on the natural convection and entropy generation in rectangular cavities with wavy-wall, ScienceDirect Energy Procedia 139 (2017) 29-36.
  6. Oztop H.F., Abu-Nada E., Varol Y., Chamkha A., (2011), Natural convection in wavy enclosures with volumetric heat sources, International Journal of Thermal Sciences, vol. 50, pp. 502-514.
  7. R. D. Flack, T. T. Konopnicki and J. H. Rooke, The measurement of natural convective heat transfer in triangular enclosures, J. Heat Transfer, Trans. ASME. 101 (1979); 648-654.
  8. R. Zarrit and al. Convection naturelle dans une cavité rectangulaire inclinée de différents rapports de forme, Revue des Energies Renouvelables Vol. 19 N°1 (2016) 97 - 109.
  9. M. Mahmoodi, Mixed convection inside nanofluid filled rectangular enclosures with movingbottom wall. Thermal Science, Year 2011, Vol. 15, No.3, pp. 889-903.
  10. S. Salari and al. Effects of circular corners and aspect-ratio on entropy generation due to natural convection of nanofluid flows in rectangular cavities. Thermal Science, (2015), Vol. 19, No. 5, pp. 1621-1632.
  11. Mebrouk, R., and al. Numerical Study of Natural Turbulent Convection of nanofluids in a tall cavity heated from below, Thermal Science, Year 2016, Vol. 20, No. 6, pp. 2051-2064.
  12. M. Salari and al. 3D numerical analysis of natural convection and entropy generation within tilted rectangular enclosures filled with stratified fluids of MWCNTs/water nanofluid and air, Journal of the Taiwan Institute of Chemical Engineers 000 (2017) 1-15.
  13. Brinkman, H.C., "The Viscosity of Concentrated Suspensions and Solutions", J. Chem. Phys., 20, 571-581 (1952).
  14. Maxwell, J.C., "A Treatise on Electricity and Magnetism", Clarendon Press, U.K, (1891).
  15. B.C. Pak, Y.I. Cho, Hydrodynamic and heat transfer study of dispersed fluids with submicron metallic oxide particles, Exp. Heat Transfer 11 (2) (1998) 151-170.
  16. B.E. Launder, D.B. Spalding, The numerical computation of turbulent flows, Comput. Methods Appl. Mech. Eng. 3 (1974) 269-289.
  17. Henkes and al. Comparison of the standard case for turbulent natural convection in a square enclosure, in a seminar on turbulent natural convection in enclosures: a computational and experimental benchmark study, ed. Henkes R. A. W. M. and Hoogendoorn, C. J., Delft, Netheriands, 1992, 185-213.
  18. Baϊri and al. Nusselt-Rayleigh correlations for design of industrial elements Experimental and numerical investigation of natural convection in tilted square air filled enclosures, Energy Conversion and Management (2008), vol. 49, pp.771-782.
  19. Marakos and al. Laminar and turbulent natural convection in an enclosed cavity, Int. J. Heat Mass Transfer (198, 27, pp. 755-772.
  20. Dixit and al. Simulation of high Rayleigh number convection in a square cavity using the lattice Boltzmann method, Int. J. Heat and Mass Transfer (2006), 49, pp.727-739.
  21. Ampofo and al. Experimental benchmark data for turbulent natural convection in an air filled square cavity, Int. J. Heat Mass Transfer, 46, pp. 3551-3572.