Using URANS to Predict Turbulent Flow Features in a Channel with Lateral Slot

摘要

Employing a commercial code an unsteady Reynolds Average Navier-Stokes (URANS) with Spalart-Allmaras as turbulence model numerical calculations were performed in order to predict the mean and velocity fluctuations fields in a rectangular channel with a lateral slot. The slot is attached to a lateral wall channel, being characterized by its deepness p and the gap width d. Simulations were performed keeping constant the slot deepness p and the length L while the gap width d was increased from 2 up to 6 mm. Three test sections involving p/d ratios--12.50，6.25 and 4.17-were studied. Main results revealed that turbulence production increases with gap dimension decreasing. Large scale structures appearance were also the target of this paper. The study showed gap width plays an important role on this issue. As the gap width was increased large scales structures could be observed farther from channel's entrance. Moreover, a kind of viscous effect in the gap was observed. As gap become very tight the frequency of coherent motions is reduced.