CFD Simulation of Cross-Ventilation in Residential Buildings under Mixed-Climate Conditions: Effects of Turbulence Models, Opening Locations, Aspect Ratios and Occupant Position

Accurate CFD simulation of coupled outdoor wind flow and indoor air flow is essential for designing effective wind-driven natural cross-ventilation in residential buildings. This study investigates indoor airflow patterns, ventilation characteristics and thermal comfort in a room containing a rectangular occupant representing a seated person, under mixed-climate conditions. Experimentally validated room dimensions and a neutral homogeneous atmospheric boundary layer (ABL) inlet are employed to ensure realistic analysis. 3D steady-state Reynolds-Averaged Navier–Stokes (RANS) simulations using different turbulence models are conducted and their performance is compared with benchmark studies. Based on a validated SST k-ω model and a fixed reference geometry, parametric analyses are performed for (1) two outlet elevations (reference case and top), (2) two inlet elevations (reference case and bottom), (3) three opening area aspect ratio (20-40%) and (4) various occupant positions. The results show that a configuration with a bottom inlet, top outlet and 30% opening area aspect ratio achieved optimal temperature stratification and velocity distribution. The optimized condition is further examined using Large Eddy Simulation (LES) with a dynamic Smagorinsky subgrid model and thermal comfort is evaluated following ASHRAE Standard 55. The findings provide insight into integrating CFD-based ventilation analysis with architectural design to enhance indoor comfort and reduce energy consumption in residential buildings.