Scale-adaptive simulation of turbulent mixed convection of nanofluids in a vertical duct

作者：Bazdidi Tehrani Farzad^*; Vasefi Seyed Iman; Khabazipur Arash

来源：Journal of Thermal Analysis and Calorimetry, 2018, 131(3): 3011-3023.

DOI：10.1007/s10973-017-6747-9

• Nanofluid
• Turbulent
• Mixed convection
• SAS approach
• Vertical duct

The present paper focuses on the turbulent mixed convection of nanofluids through a vertical square duct. The prediction accuracy of scale-adaptive simulation (SAS) approach is investigated versus RANS-based models (k - epsilon and k - omega), in terms of Nusselt number and friction factor. A thermal-dependent model is considered to determine the effective thermal conductivity and effective dynamic viscosity of nanofluids. The present numerical simulations are performed for CuO-water and SiO2-water nanofluids and compared with various experimental data. Results indicate that the SAS approach can predict the unsteady flow and heat transfer of nanofluids more accurately than the k - epsilon and k - omega models. Moreover, it is found that the turbulent velocity fluctuations enhance in streamwise, spanwise and wall-normal directions with an increasing nanoparticle volume fraction, whilst this increment is higher in streamwise direction. Also, in the near-wall region the effect of the presence of nanoparticles on the turbulent velocity fluctuations is more considerable, which increases the turbulence content of the flow field.

• 出版日期2018-3