A Comparative Analysis of Turbulence Models Utilised for the Prediction of Turbulent Airflow through a Sudden Expansion

Abstract

The turbulent airflow in a circular duct with sudden expansion was investigated utilizing three turbulence models. The turbulence models chosen are: the k-epsilon model, the shear stress transport model and the Reynolds-stress model. The performance of the models was investigated with respect to the flow parameter-recirculation length. The turbulent kinetic energy and velocity predictions were compared between the turbulence models and with experimental data, then interpreted on the basis of the recirculation length. From the results, the shear stress transport model predictions of recirculation length had the closest agreement with the experimental result compared to the other model. Likewise, the convergence rate for the shear stress transport model was reasonable compared to that of the Reynolds model which has the slowest convergence rate. In light of these findings, the shear stress transport model was discovered to be the most appropriate for the investigation of turbulent air flow in a circular duct with sudden expansion. Keywords: Turbulence, recirculation length, sudden expansion, Turbulence models.

Fractal Geometric Model for Statistical Intermittency Phenomenon

“…However, the Kolmogorov's theory does not agree with the results of many numerical and experimental studies carried out later, showing significant deviations from the linearity of scaling exponents assumed by Kolmogorov [1,[8][9][10][11][12][13][14]. This deviation from linearity (homogeneity's assumption) is due to the intermittent characteristics of energy dissipation, where the gradient of turbulent flows fluctuates significantly over the volume occupied by the fluid [15][16][17]. This phenomenon is known as "intermittency".…”