University of Technology-IraqEngineering and Technology Journal1681-690029620110401A Numerical Prediction of the Turbulence Parameters in Two-Dimensional Ventilated Rooms105210683092210.30684/ etj.29.6.2ENAyad M. SalmanJournal Article20110401Turbulent flow in two-dimensional ventilated room has been numerically<br /> simulated in the present research. A modified form of Wilcox's two-equation LRN<br /> k-w model is proposed for predicting internal turbulent ventilation flows. The<br /> modifications include adding a turbulent cross-diffusion term in the w-equation,<br /> and re-establishing the closure constants and damping functions, with the<br /> application of the wall-function method. The turbulent cross-diffusion for specific<br /> rate, w, is modeled with two parts: a second-order diffusion term and a first-order<br /> cross-diffusion term.<br /> The air was used as the working fluid, and the length of ventilation enclosure (9<br /> m), and height of ventilation enclosure (3 m). The study was made for Reynolds<br /> number values of (Re=7.5´103).<br /> A finite volume method is used with a staggered grid arrangement. The<br /> continuity, momentum and turbulence model equations are solved with hybrid<br /> method by using SIMPLE algorithm. A computer program in FORTRAN (90) was<br /> developed to carry on the numerical solution. The Computational algorithm is<br /> capable of calculating the hydrodynamic and turbulence properties such as the<br /> velocity, and turbulent kinetic energy, specific dissipation rate (w), turbulent<br /> Reynolds stress, and terms of convection, production, diffusion, destruction,<br /> turbulent cross-diffusion and square root mean of fluctuating velocity. The results<br /> showed the peak value of velocity near the wall jet region and negative value of<br /> velocity near the bottom region (floor region) i.e. recirculating zone. The<br /> maximum value of turbulent kinetic energy near wall jet region in the first<br /> horizontal section of ventilation enclosure, and the profile become flattened in the<br /> second section of ventilation enclosure room. The same behavior in the turbulent<br /> Reynolds stress distribution because depending on velocity in his calculations. The<br /> same behavior between production term and destruction term but the values of<br /> production term is positive and the value of destruction term is negative. The<br /> distribution approximately symmetry.<br /> The numerical results were compared with other previous theoretical results.<br /> The agreement was good, confirming the reliability of the proposed mathematical<br /> model and computational algorithm in investigating the performance of turbulence<br /> model in numerical simulation of turbulent ventilation flows.https://etj.uotechnology.edu.iq/article_30922_a7520d0165036947864305d50f6492c9.pdf