IMPACT OF MULTIZONE MODEL BOUNDARY CONDITIONS ON THE CFD PREDICTION OF ROOM AIRFLOW AND CONTAMINANT CONCENTRATIONS DISTRIBUTION

Coupling CFD and multizone models can avoid their respective drawbacks in predicting airflow andcontaminant concentrations distribution in buildings. Two kinds of boundary conditions are commonlyexchanged between them. The multizone model can give either pressure or mass flowrate boundaryconditions to CFD. This study analyzes in detail the impact of each of the boundary types on the CFDdomain, and compares them with a full CFD simulation without coupling. This study shows that incoupling CFD with multizone, the accuracy of the CFD prediction part depends mainly on the accuracyof the boundary conditions being imposed at their interface. When modeling a very small opening,pressure boundary conditions give slightly more accurate results. For a moderate opening height, bothpressure and flow rate boundary conditions show good agreement with the CFD-only simulation. For alarge opening, the mass flow rate boundary conditions are better to use.