FMA Challenge 2: Difference between revisions

Data for this model is provided viain ZIPa compressedvariety fileof availabledifferent [http://www.tuflow.com/Tuflow%20Tutorial%20Models.aspxGIS compatible onformats. Download the TUFLOWdataset Downloadsthat Page]matches underthe 'CurrentGIS Demosoftware Models'.you are using:

*General 2D modelling - <u>[[Tutorial Module01Tutorial_M01|Tutorial Module 1]] </u>

*2D topography modification - <u>[[Tutorial Module03Tutorial_M02|Tutorial Module 32]]</u><br><br>

It is at your discretion which GIS package, text editor and method of model simulation to use (batch mode or within the text editor). All files required to setup and run the models are available within the download package. You have the choice of running with shape file or mif for usage in ArcGIS/QGIS or Mapinfo respectively.<br> <br>

Generally Manning’s n values are very similar for 1D and 2D schemes. Where there is rapid changes in flow direction and magnitude (ege.g. at a structure, sharp bend or embankment opening), fully 2D schemes will simulate energy losses associated with the change in flow patterns, whereas 1D schemes either require user specified energy losses (ege.g. a structure) or artificially increasing Manning’s n. In these situations 1D schemes may utilize higher Manning’s n values than 2D schemes. Conversely, 2D schemes typically apply no side wall friction, so if there is significant wall friction a 2D scheme may require a slightly lower Manning’s n than a 1D scheme.

<li>The modeller should NOT adopt unrealistic parameter values (ege.g. excessively low or high Manning’s n values) for the sole purpose of achieving a good calibration. It is invariably the fact that there are other uncertainties causing the discrepancy when unrealistic Manning’s n values are used. Unrealistic Manning’s n values or other parameters (ege.g. high eddy viscosity) distort the results and are a sure sign that there is something else wrong.