TY - CPAPER
DO - https://doi.org/10.26868/25222708.2021.30482
UR - https://publications.ibpsa.org/conference/paper/?id=bs2021_30482
PY - 2021
DA - 2021/September
PB - IBPSA
AU - Lup, Wai Chew
AU - Chen, Chen
AU - Catherine, Gorlé
TI - CFD-Based Analysis of the Discharge Coefficient for Buoyancy-Driven Ventilation in a Full-Scale Operational Building
T2 - Proceedings of Building Simulation 2021: 17th Conference of IBPSA
VL - 17
SN - 978-1-7750520-2-9
C1 - Bruges, Belgium
J2 - Building Simulation
SP - 3096-3102
AB - Natural ventilation can play a key role in reducing building energy consumption for ventilation and cooling. The ventilation rate across an opening can be characterized using a still-air discharge coefficient, Cd, which is often assumed to be constant for a given opening. We aim to evaluate this constant Cd assumption for the buoyancy-driven natural ventilation process in Stanfordâ€™s Y2E2 Building. Computational fluid dynamics (CFD) simulations, specifically large eddy simulations, are used to calculate the flow rate through each window and determine the corresponding Cd. The validated CFD results show that Cd decreases linearly with Reynolds number (Re, calculated based on the flow rate across the windows) when Re < 10,000 but stays constant around 0.51 when Re > 10,000. As a result, assuming a constant Cd to estimate natural ventilation rate can introduce significant errors. Widespread use of CFD would support a more accurate characterization of the dependency of Cd for Re for specific building geometries and support robust natural ventilation system design.
ER -