On the Modelling of Thermal Buoyancy Flows Involving Laminar–Turbulent Transition

Laminar–turbulent transition is a phenomenon that extensively exists in many fluid flows. Accurate and cost-effective modelling of the transition is of fundamental importance for the design and diagnosis of relevant flow processes and industry systems. Existing transition turbulence models were mostly developed for high-speed aerodynamics applications. Their suitability for buoyant low-speed flows, such as natural and mixed convection flows, has been rarely assessed. This study aimed to bridge this gap through comparing the velocity and temperature fields yielded from various transition turbulence models against the experimental data of natural convection flow in a differentially heated cavity. The results showed that Wilcox’s low-Re modification to the SST k-ω model and the transport γ-equation had good accuracies for low-speed natural convection flows. Other models, including the algebraic γ-equation, γ-Reθ model and kt-kl-ω model, overpredicted the turbulence quantities, resulting in significant predictive errors in velocity and temperature simulations.