TUFLOW Version Backward Compatibility: Difference between revisions
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* New features that use GIS attributes previously reserved (i.e. unused). If these attributes were not populated with the recommended “reserved” value (usually 0 or blank), then they can cause unpredictable results in later releases.
* Bug fixes noting that most bug fixes are input/output related and rarely affect the model's hydraulic calculations.
* Change in timestepping can also produce a small change in results. HPC uses the Runge-Kutta 4th order integrator, which is usually fairly insensitive to time step provided the model is running stably. However when a region is filled by flow that only just overtops an embankment, a 10 mm difference in water levels upstream of the embankment can create a much larger difference in levels downstream. Hence, small differences in time-stepping (along with many other aspects of model setup) can trigger local differences in model results.
* Model orientation (if changed) could also mean slight change in results. This is mostly given by interpolating values from different calculation points. Every cell has nine calculation points. Based on the model origin, all or most of the calculation points would have different topography elevation sampled, which translates to slightly different results.
* If using 1D channel, possibly different cells have been selected as HX boundary and might have different elevations. This can be reviewed in <u>[[Check_Files_1d_to_2d_bc | 1d_to_2d check file]]</u>.
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