MODIFICATION OF THE κ-ε TURBULENCE MODEL FOR SWIRLING RECIRCULATING FLOW IN A PIPE EXPANSION

SUMMARY A modified turbulence model, incorporating anisotropic effects into the standard κ-ε model, is proposed for the numerical simulation of swirling recirculating flow in a pipe expansion. The new modification follows the concept that the correction to the standard κ-ε model is made only in the flow regions where the anisotropic effects are appreciable. The performance of the present hybrid κ-ε model for two swirling flows with moderate and high swirl levels is better than that of the standard κ-ε model and the modified κ-ε model proposed by Abujelala and Lilley and is also competitive with our previously developed hybrid κ-ε model. Moreover, the present hybrid modification provides a relatively simpler form compared to our previously developed model; this also helps alleviate the numerical instability in the calculation procedure. Encouraging improvement in the prediction of the size of the central toroidal recirculation zone using the present hybrid modification is also exhibited