Numerical calculation is performed for turbulent mixed convection with property variation in a vertical heated pipe using the commercial software, FLUENT. It is found that, at low Reynolds-number, the turbulence models available in the FLUENT yield very poor prediction, as most of the low-Reynolds number k-ε turbulence models do.
To overcome this discrepancy, a new turbulence model is proposed taking into account of low Reynolds-number effect. This model is based on the eddy-viscosity model of Okamoto & Shima(2003, TCFD 16 p.369) and includes no near-wall treatments in the Reynolds stress model. The prediction performance of the present model is compared with those of four other low-Reynolds number k-ε turbulence models for turbulent forced-convection heat transfer. The Reynolds number ranges from 4,000 to 10,000. For eddy-diffusivity model, three different turbulent Prandtl number models are employed. For low Reynolds-number flow, the present model performs very well in Nusselt number and skin friction.
