Nested Hydrodynamic Modeling Using the MIKE 3 Model

The numerical technique adopted in a hydrodynamic model using multiple grids of different spatial resolutions is described. The nested grid configuration can reduce the CPU time compared to the standard approach of using only one fixed grid size. Typically applications of hydrodynamic models have a limited physical area of main interest. A standard hydrodynamic model can be set up using one grid size, but this will often result in a very large number of computational grid points beyond the area of main interest. This approach will require a large amount of computer time and memory. When applying a multiple grid resolution set-up, it is necessary to ensure conservation of mass and momentum during the dynamic exchange between coarser grid region and the finer grid regions. This nested model design included a simple test channel with dimensions of 12,000m x 300m x 10m. The initial condition was set up as still water. The driving force in the model is a simple 5 cm set-up and 5 cm set-down at the closed ends of the channel. Fifteen 300m x 300m x 10m coarse grids were used in both channel closed ends, making the channel cross-section only one cell wide. Thirty 3-cell fine grid cross-sections were nested in the middle of the channel. The fine grid size was 100m x 100m x 10m, creating 3 cells in the channel cross-section. The MIKE 3 model was set up with 10 vertical layers. The model was simulated until a steady state was achieved conservation of mass and momentum was then verified between a fine grid cross-section and two coarse grid cross-sections. A real application in which the nested MIKE 3 model has been used is also described. This application illustrates that the nesting technique successfully can be adopted without compromising the model accuracy and performance. The applied nesting technique is thus an efficient tool to optimize simulations with otherwise excessive and potentially prohibitive run times.

Language

  • English

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 949-968
  • Monograph Title: Estuarine and Coastal Modeling

Subject/Index Terms

Filing Info

  • Accession Number: 01005908
  • Record Type: Publication
  • ISBN: 0784407347
  • Files: TRIS
  • Created Date: Oct 14 2005 2:18PM