Numerical study of turbulent flow in heated circular tube using transitional shear stress transport turbulence model

• Low Re turbulent flow in vertical tubes simulated using transitional SST model.
• Transitional SST model predictions agree well with experimental and DNS results.
• The transitional SST model accurately predicts laminarization.
• Nusselt number correlation, pressure drop correlation, and laminarization criterion are proposed.

Low Reynolds number turbulent air flow moving upward in a vertical circular tube subjected to high heating rates was simulated using the transitional shear stress transport (SST) model for an inlet Reynolds number range of 4000 ≤ Rein ≤ 10,000 and a non-dimensional heating rate range of 0.001≤qw+≤0.005. The transitional SST model was validated by comparing pressure drop, Stanton number, and local velocity and temperature profiles with available experimental data and DNS results. The good agreement obtained between the transitional SST turbulence model predictions and the experimental data and DNS results shows that the transitional SST turbulence model is able to predict laminarization accurately. Parametric calculations using the validated transitional SST model were performed to obtain Nusselt number and pressure drop correlations. In addition, a laminarization criterion that is based on the attenuation of Reynolds shear stress due to flow laminarization is proposed. The laminarization criterion predicts a reduction in the Nusselt number as compared to the constant property results, ranging from as much as 62% reduction for Rein = 4000–23% reduction for Rein = 10,000.