Numerical simulation of Al2O3–water nanofluid mixed convection in an inclined annulus

Document Type: Research Paper


1 Faculty of Mechanical Engineering, Tarbiat Modares University, Iran P.O. Box 14115-143 Tehran, Iran

2 Faculty of Aerospace Engineering, KNTU, P .O. Box 16765-3381 Tehran, Iran


Laminar mixed convection of Aluminium oxide (Al2O3)–water nanofluid flow in an inclined annulus using a single-phase approach was numerically studied. Constant heat flux boundary conditions were applied on the inner and outer walls. All the thermophysical properties of nanofluid, such as, viscosity, heat capacity, thermal conductivity, and thermal expansion coefficient, except density in the body force term were assumed to be constant. Based on Boussinesq’s hypothesis, density was assumed to be a linear function of temperature. The nanofluid properties were calculated in terms of constant properties of nanoparticles and the base fluid. Using the finite volume method the continuity, momentum, and energy equations were numerically solved. Numerical simulations were conducted for the nanoparticle concentrations of 0, 2, and 5% and five different inclination angles including-30o,-15o ,0 , +15o, and+30o. Results showed that a variation in the inclination angle affected the Nusselt number on the inner wall more than the outer one. The Nusselt number in negative angles was higher than in the positive ones, so that at a volume fraction of 5%, the average Nusselt number at the inner wall decreased almost 2% when changing the angle from -30o to+30o. The local Friction factor in the positive angles was higher than in the negative ones.


[1] Choi S.U.S., Enhancing Thermal Conductivity of Fluid with Nanoparticles, Developments and Applications of Non-Newtonian Flow, ASME, FED 231/MD, 66 (1995) 99–105.

[2] Yu W., Xie H., Chen L., Li Y., Investigation of Thermal Conductivity and Viscosity of Ethylene Glycol Based ZnO Nanofluid, Thermochim. Acta, 491 (2009) 92–96.

[3] Zhang X., Gu H., Fujii M., Effective Thermal Conductivity and Thermal Diffusivity of Nanofluids Containing Spherical and Cylindrical Nanoparticles, Exp. Therm. Fluid Sci. 31 (2007) 593–599.

[4] Xie H., Fujii M., Zhang X., Effect of Interfacial Nanolayer on the Effective Thermal Conductivity of Nanoparticle-Fluid Mixture, Int. J. Heat Mass Trans. 48 (2005) 2926–2932.

[5] Nguyen C.T., Desgranges F., Galanis N., Roy G., Maré T., Boucher S., Angue Mintsa H., Viscosity Data for Al2O3–Water Nanofluid-Hysteresis: Is Heat Transfer Enhancement Using Nanofluids Reliable?, Int. J. Therm. Sci. 47 (2008) 103–111.

[6] Masoumi N., Sohrabi N., Behzadmehr A., A New Model for Calculating the Effective Viscosity of Nanofluids, J. Phys. D: Appl. Phys. 42 (2009) 055501 (p. 6).

[7] Maige S.E., Nguyen C.T., Galanis N., Roy G., Heat Transfer Behaviors of Nano fluids in a Uniformly Heated Tube, Superlattices Microstruct. 35 (3-6) (2004) 543-557.

[8] Roy G.,   Nguyen C.T.,    Lajoie P.R., Numerical Investigation of Laminar Flow and Heat Transfer in a Radial Flow Cooling System with the Use of Nanofluids, Superlattices Microstruct. 35 (3-6) (2004) 497-511.

[9] Khanafer K., Vafai K., Lightstone M., Buoyancy Driven Heat Transfer Enhancement in a Two Dimensional Enclosure Utilizing Nanofluids, International Journal Heat Mass Transfer. 46 (2003) 3639-3653.

[10] Akbarinia A., Behzadmehr A., Numerical Study of Laminar Mixed Convection of a Nanofluid in Horizontal Curved Tubes, Journal Appl. Thermal Eng. 27 (2007) 1327-1337.

[11] Sundar L.S., Sharma K.V., Parveen S., Heat Transfer and Friction Factor Analysis in a Circular Tube with Al2O3 Nanofluid by Using Computational Fluid Dynamics, International Journal Nanoparticles. 2 (1-6) (2009) 191-199.

[12] Bianco V., Chiacchio F., Manca O., Nardini S., Numerical Investigation of Nanofluids Forced Convection in Circular Tubes, Appl. Thermal Eng. 29 (2009) 3632-3642.

[13] He Y., Men Y., Zhao Y., Lu H., Ding Y., Numerical Investigation into the Convective Heat Transfer of TiO2 Nanofluids Flowing Through a Straight Tube under the Laminar Flow Conditions, Appl. Thermal Eng. 29 (2009) 1965-1972.

[14] Abu-Nada E., Effects of Variable Viscosity and Thermal Conductivity of Al2O3– Water Nanofluid on Heat Transfer Enhancement in Natural Convection, International Journal Heat Fluid Flow. 30 (2009) 679-690.

[15] Abu-Nada E., Masoud Z., Hijazi A., Natural Convection Heat Transfer Enhancement in Horizontal Concentric Annuli Using Nanofluids, International Commun. Heat Mass Trans. 35(2008) 657-665.

[16] Izadi M., Behzadmehr A., Jalali-Vahida D., Numerical Study of Developing Laminar Forced Convection of a Nanofluid in an Annulus, International Journal Therm. Sci. 48 (2009) 2119-2129.

[17] Ben Mansour R., Galanis N., Nguyen C.T., Experimental Study of Mixed Convection with WatereAl2O3 Nanofluid in Inclined Tube with Uniform Wall Heat Flux, International Journal of Thermal Sciences. 50 (2011) 403-410.

[18] Mokhtari Moghari R., Akbarinia A., Shariat M., Talebi F., Laur R., Two Phase Mixed Convection Al2O3–Water Nanofluid Flow in an Annulus, International Journal of Multiphase Flow. 37 (2011) 585–595.

[19] Maxwell J.C., A Treatise on Electricity and Magnetism, second ed., Clarendon Press, Oxford University, UK, (1881).

[20] Pak B.C., Cho Y.I., Hydrodynamic and Heat Transfer Study of Dispersed Fluids with Submicron Metallic Oxide Particles, Exp. Heat Transfer. 11 (1998) 15.

[21] Xuan Y., Roetzel W., Conceptions for Heat Transfer Correlation of Nanofluids, International Journal Heat Mass Transfer. 43 (2000) 3701.

[22] Drew D.A., Passman S.L., Theory of Multi Component Fluids, Springer, Berlin, (1999).

[23] Khanafer K., Vafai K., Lightstone M., Buoyancy Driven Heat Transfer Enhancement in a Two Dimensional Enclosure Utilizing Nanofluids, International Journal Heat Mass Trans. 46 (2003) 3639–3653.