Data

The drag coefficient and the roughness height, k_s, can be specified in one of three ways

·         Constant (in time and domain)

·         Constant in time, varying in domain

·         Varying in time and domain

For the case with values varying in domain you have to prepare a data file containing the drag coefficient, the roughness height or the grain diameter before you set up the hydrodynamic simulation. The file must be a 2D unstructured data file (dfsu) or a 2D grid data file (dfs2). The area in the data file must cover the model area. If a dfsu-file is used piecewise constant inter­polation is used to map the data. If a dfs2-file is used bilinear interpolation is used to map the data. If the data is varying in time the data must cover the complete simulation period. The time step of the input data file does not, how­ever, have to be the same as the time step of the hydrodynamic simulation. A linear interpolation will be applied if the time steps differ.