Development of an Adaptive Boundary-Fitted Coordinate Code for Use in Coastal and Estuarine Areas.
Abstract
Most coastal and estuarine systems that have problems requiring numerical hydrodynamic and transport modeling contain winding navigation channels. Accurate and efficient modeling of flow and suspended sediment transport requires a numerical grid that follows the navigation channel with a fine gird spacing in the channel, while retaining a larger spacing in the remainder of the field. A computer program called WESCORA has been developed to enable the numerical computation of such boundary-fitted grids for use in the finite difference modeling of flow and constituent fields. Two adaption mechanisms are included, one based on a variational principle and the other based on control functions, with the former being apparently the more consistent and reliable. With the variational approach, a functional that consists of the sum of three integrals involving the physical coordinates is minimized over the grid. The first of the integrals controls gird point concentration by forcing the grid points to cluster where the water depth is large, i.e., in navigation channels. The other two integrals control grid smoothness, i.e., the rate of change of grid spacing and the skewness of the coordinate lines. By weighting the importance of the three integrals, either grid point concentration, gird smoothness, or orthogonality can be emphasized. Mathematical aspects of the grid generation equations and the interpolation schemes employed for the water depths are discussed. In addition, example grids generated on Chesapeake Bay are presented. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1985
- Accession Number
- ADA168575
Entities
People
- Billy H. Johnson
- Joe F. Thompson