Two-Dimensional Dam-Break Flow Simulation in a Sudden Enlargement

by M. ?etina, Univ of Ljubljana, Hajdrihova, Slovenia,
R. Rajar, Univ of Ljubljana, Hajdrihova, Slovenia,



Document Type: Proceeding Paper

Part of: Modelling of Flood Propagation Over Initially Dry Areas

Abstract:

The paper presents the use of a two-dimensional depth averaged mathematical model for an unsteady dam-break flow simulation in a sudden enlargement. Continuity and two momentum equations for depth averaged horizontal velocities u and v are solved numerically by the use of a control-volume formulation of the finite difference approach. The main features of this method are: the space staggered grid with a hybrid scheme, and a fully implicit time scheme. An iterate solution procedure with pressure-correction (SIMPLE algorithm) is used. A basic computer program TEACH was accomplished. It takes into account irregular geometry and time derivatives in the equations; the so called `rigid lid approximation' was also suppressed. Some simple, unsteady, one-dimensional flows in the two prismatic rectangular channels were computed first. The waves simulated by the proposed two-dimensional model were very similar to those predicted by already verified one-dimensional implicit schemes. Finally, an unsteady flow in a rectangular channel with a sudden enlargement was simulated. A qualitative comparison of the results with those observed on a physical model shows good agreement. Qualitatively, the computed maximal water depth in the area was only 3% greater than the experimental value. This is quite acceptable for practical purposes.

Subject Headings: Two-dimensional models | Flow simulation | Dam failures | Two-dimensional flow | Approximation methods | Computer models | Unsteady flow

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