Indoor turbulent airflow modelling with a new integral buoyant wall function

Indoor airflows CFD modelling requires relevant prediction of natural convective heat transfer at wall boundaries. On the one hand, widely used eddy viscosity turbulent models such as k−ɛ or k−ωSST combined with standard wall function perform poorly for the prediction of walls heat fluxes. Improvement of wall heat fluxes prediction requires wall-resolved meshes combined with advanced turbulence models which are generally computationally demanding while not always feasible for complex geometries. On the other hand, zonal and nodal models are widely used to predict building thermal behaviour. These models rely on integral scale correlation to predict room wall heat fluxes but give very limited information about local behaviours. The present study investigates the use of integral scale based wall functions to reach a reasonable compromise between the computational cost of wall-resolved models and the required accuracy for fields of interest such as temperature or velocity.