Computational fluid dynamics for HVAC: successes and failures

The computational fluid dynamics (CFD) technique has been used for different flow and heat transfer problems in the heating, ventilating, and air-conditioning (HVAC) industry in the last two decades. Considerable success has been achieved; however, there are still some uncertainties. This paper shows that some uncertainties are the results of the many approximations used in turbulence models, numerical algorithms, and discrete methods. It is important that CFD program users should have a good knowledge of turbulent flows and numerical techniques to perform correct simulations. In addition, with the present capacity of computers and the accuracy of measurement techniques, it is difficult to achieve a completely satisfactory validation of numerical predictions. The predictions of mean parameters such as velocities and temperatures by the CFD technique are more accurate than the turbulent variables such as turbulence intensities.