Three-dimensional numerical modelling of flows over a natural dune field

HARDY R,; PARSONS D,; L BEST, JAMES; LANE J,; KOSTASCHUCK R,; OSCAR ORFEO

Lisboa

Congreso; River Flow 2006, International Conference on Fluvial Hydraulics; 2006

ABSTRACT: Our ability to numerically predict the interaction between complex topography and three di-mensional flow at large scales (~1 km) has yet to be fully developed. This is the result of our inability to de-sign numerically stable meshes for complex topographies at these spatial resolutions. This paper deals with the numerical simulation of flow over a natural dune field located in the Rio Paraná, NE Argentina. The methodology is based upon the development and application of a new five term porosity algorithm that modi-fies the mass conservation equation within a regular Cartesian mesh. Bathymetric measurements were made in the field using a multibeam echo sounder which provided an unparalleled topographic dataset to test this new numerical modeling approach. Measurements of flow were made using an acoustic Doppler current pro-filer and are used as inlet boundary conditions and validation data. The results demonstrate simple flow accel-eration due to topographic forcing over the dune stoss and expansion and deceleration over the dune lee.