HPC Model Review: Difference between revisions

<font color="blue"><tt>Map Output Data Types </tt></font><font color="red"><tt>==</tt></font><tt> dt </tt> writes the minimum dt (timestep) calculated for each cell in the model to the specified Map Output Format (XMDF, DAT, ASC, FLT etc.). Reviewing this output helps modellers identify which cells in the model have the lowest timestep and thereby control the model timestep. These locations are likely to have the greatest depth, velocity or turbulence in the model, forcing TUFLOW to lower the timestep to satisfy the conditions of the controlling numbers mentioned in the <u>[[HPC_Adaptive_Timestepping | HPC Adaptive Timestepping]]</u> page. If the timestep is extremely low the HPC model might be “hiding” poor data or model setup in this location. The simulation timestep will always be limited by the minimum occurring timestep anywhere in the model, hence it is important to ensure timestepping isn’t being unnecessarily restricted due to poor model configuration in one spot, even only in one cell. <br>

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The cause of the low timestep may become clearer when observing it geographically in the dt Map Output, as the low timestep may occur close to specific hydraulic features. This is seen in the example above, where an unusually low dt value is observed upstream, where the road intersects a local channel. It is helpful to review this in conjunction with the hpc.dt.csv to know which of the controlling numbers is causing the timestep to be lowered.<br>