Author(s): M. Nassiri; S. Babarutsi; V. H. Chu
Linked Author(s): Sofia Babarutsi, Vincent H. Chu
Keywords: Open-Channel Flow; Recirculating flow; Bottom friction; Numerical Computation; Turbulence Model; K-εModel; Wall Function; Boundary Condition; Mixing; Inland and Coastal Waterways
Abstract: Despite the dominant effect of the bottom friction, the wall boundary conditions still have a significant role in the structure of the recirculation open-channel flow of shallow depth. Numerical calculations are conducted to determine the recirculation flow in a sudden open-channel expansion using the two-length-scale k-εmodel. Two different wall boundary conditions, based (i) on the logarithmic law of the wall and (ii) on a two-layer model including the effect of viscosity, are employed in the calculations. The results show that the reattachment length and the recirculation flow rate of the main eddy are not significantly affected by the wall boundary conditions. However, the secondary (corner) eddy which was observed in the laboratory experiments, is produced only when the two-layer model is selected for the calculations. The implication of this numerical results on mathematical modeling of mixing process in the low flow region of inland and coastal waterways are examined in this paper.
Year: 1999