This paper is based on findings resulting from ASHRAE Research Project RP-1493.

This paper is a summary of a study conducted by the team at HVAC design d.o.o. Sarajevo in the framework of the ASHRAE RP-1493 CFD Shootout Contest—Prediction of Duct Fitting Losses. In the introductory section, methods of airflow modeling and simulation used in this analysis are briefly described. This is followed by a presentation of a set of validation results that were used to select appropriate simulation parameters. Next, computational fluid dynamics (CFD) results of pressure loss coefficients in flat-oval ducts and tee and lateral duct fittings at different flow rate ratios and Reynolds numbers in both converging and diverging flow modes are compared to empirical correlations and measurements. Obtained duct fitting simulation results are generally in qualitatively good agreement with laboratory data.