NUMERICAL INVESTIGATION OF TURBULENT SHALLOW RECIRCULATING FLOWS BY A QUASI-THREE-DIMENSIONAL k–ϵMODEL
✍ Scribed by C. W. LI; T. S. YU
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 723 KB
- Volume
- 23
- Category
- Article
- ISSN
- 0271-2091
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✦ Synopsis
A quasi-three-dimensional multilayer k-c model has been developed to simulate turbulent recirculating flows behind a sudden expansion in shallow waters. The model accounts for the vertical variation in the flow quantities and e l i t e s the problem of closure for the effective stresses resulting from the depth integration of the nonlinear convective accelerations found in the widely used depth-integrated models. The gweming equations are split into three parts in the finite difference solution: advection, dispersion and propagation. The advection part is solved using the four-node minimax-characteristics method. The dispersion and propagation parts are treated by the central difference method, the former being solved explicitly and the latter implicitly using the Gauss-Seidel iteration method. The relative effect of bed-generated turbulence and transverse shear-generated turbulence on the recirculating flow has been studied in detail. In comparison with the results computed by the depth-integrated k-c model, the results computed by the present model are found to be closer to the reported data. KEY WORDS shallow recirculating flow; multilayer model; turbulence model k-6 model and studied the recirculating flow generated by a side discharge into an open channel.
Booij3 and Yu and Zhang4 presented several different versions of the k-c model. In these models the rigid lid assumption was employed. This assumption allows only a linear variation in the water surface and wave formation at the water surface will be suppressed. In contrast, Chapman and Kuo' developed a depth-integrated kc model which allows free surface variation. When simulating recirculating flows, these depth-integrated k-c models were found to underpredict the reattachment length. It is widely accepted that this is due to the inadequacy of the k-c model for turbulence.
However, in flow simulation using depth-integrated models, the effect of the vertical variation in the flow quantities has not been explicitly accounted for. In particular, the problem of closure of the