Assessment of a common nonlinear eddy-viscosity turbulence model in capturing laminarization in mixed convection flows

Laminarization is an important topic in heat transfer and turbulence modelling. Recent studies have demonstrated that several well-known turbulence models, failed to provide accurate prediction when applied to mixed convection flows with significant re-laminarization effects. One of those models, a well-validated cubic non-linear eddy-viscosity model, was observed to miss entirely this feature. This paper studies the reasons behind this failure by providing a detailed comparison with the baseline Launder-Sharma model. The difference is attributed to the method of near-wall damping. A range of tests have been conducted and two noteworthy findings are reported for the case of flow re-laminarization.