Print Email Facebook Twitter Improved simulation of main flow and secondary flow in a curved open channel Title Improved simulation of main flow and secondary flow in a curved open channel Author Pennekamp, J.G.S. Booij, R. Faculty Civil Engineering and Geosciences Department Hydraulic Engineering Date 1984-01-01 Abstract For the computation of depth averaged flows in tidal channels and rivers a recently developed fully implicit finite difference method of the ADI-type proved vastly superior to the partly explicit variants, commonly used. The fully implicit variant allowed a relatively large time step in combination with arealistic lateral diffusion coefficient. The fully implicit method, used, requires a square grid for the time being. The irregular numerical representation of the sidewalls of a curved channel or flume gives rise to disturbances in the computed flow field. In this report a correction scheme to keep the disturbances small is considered. In this scheme a correction is realized by a modification of the depth near the sidewalls. The correction scheme is actually a combination of two different corrections. The first correction is aimed at forcing the velocity at corner points of the computational grid in the direction of the physical boundary. The second correction compensates for the local narrowing and widening of the flow by the irregular numerical representation of the sidewalls. The influences of both corrections appear to be small when applied separately, but the combination of the two corrections has, however, important consequences. The application of the combined corrections on the simulation of steady flow in a curved flume with a rectangular cross-section annihilates nearly the important disturbances caused by the use of a rectangular grid. For a curved flume with the geometrical proportions of a river, in which case the disturbances proved much less important, a less important amelioration is obtained. For flow in tidal channels even smaller disturbances and less improvement are expected. The effect of the corrections is very sensitive to the exact waterdepth at the sidewalls. In time dependent flows it is therefore difficult to apply the right corrections. Further improvement will have to await the possibility to use a curvilinear grid in the fully implicit finite difference method. This research is aimed at the computation of secondary flow in tidal channels based on the depth averaged velocity field. The improved computation of the depth averaged velocity field brings about an improved computation of the secondary flow. Knowledge of the secondary flow in a tidal channel is essential for predictions about the morphology of the bottom. Subject flow simulationsecondary flowcurved open channeldepth averaged flowfully implicitgrid To reference this document use: http://resolver.tudelft.nl/uuid:5ed0f393-0f2c-4ccb-b87e-cba06bde84cb Publisher TU Delft, Department of Hydraulic Engineering Source Report no. 1-84 Part of collection Institutional Repository Document type report Rights (c) 1984 TU Delft, Department of Hydraulic Engineering Files PDF Pennekamp_Booij1984.pdf 8.74 MB Close viewer /islandora/object/uuid:5ed0f393-0f2c-4ccb-b87e-cba06bde84cb/datastream/OBJ/view