An Evaluation of Turbulence Models for the Numerical Study of Forced and Natural Convective Flow in Atria

Abstract

A demand for methods that can be used in the numerical analysis of three dimensional air flow in large buildings has developed as more buildings are being designed with large atriums using a solar loading that leads to complex flow. The flow in such buildings is almost always turbulent which means that turbulence models that are accurate but which do not require undue computer resources have to be selected. As a result, a numerical study of natural convective heat transfer and turbulent flows in large atria, specifically part of the Atria in the EV building at Concordia University, has been completed. Experimental work on turbulence modeling and atria design has been studied and compared with the numerical results obtained here to gain confidence in the modeling techniques used in the study. The flow has been assumed to be steady, and the Boussinesq approximation has been used. The governing equations have been numerically solved using the CFD solver FLUENT. The three-dimensional air flow in the Concordia-like atria used the following parameters: forced flow vent inlet angle; forced flow vent velocity; date and time (for solar radiation purposes). The case with adiabatic floor and ceiling conditions was examined and compared to the case with isothermal floor and ceiling conditions. Several models were studied to compare the effect of turbulent modeling in the atria, including the following: (1) K-Epsilon; (2) K-Omega; (3) Detached Eddy Simulation (DES) model; (4) Large Eddy Simulation (LES) model. Further study was completed after it was noted the flow was completely based on natural convection when the velocity of the inlet flow was set to zero. In addition, experimental results were available and this situation was modeled using similar parameters to the work explained above. Comparing these results supported the accuracy of the work done on the Concordia Atrium. Experimental work on the Annex 26 Atrium in Yokohama Japan was also compared to numerical results to gain confidence in techniques used in the present study and results were obtained that were in good agreement.