TUFLOW 2D Cell Size Selection: Difference between revisions

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[[File:Mesh_Converge_XS_20m.png|500px]][[File:Mesh_Converge_XS_10m.png|500px]][[File:Mesh_Converge_XS_05m.png|500px]]<br>
 
Unfortunately it isn't practical for all models to be designed at an infinitely fine resolution due to the cost it has on simulation speed. Increasing a model resolution will make a simulation run slower. As a rule of thumb, halving the cell size in a model will typically increase the simulation run time by a factor 8. This is due to the number of cells increasing by a factor of (4) four and the necessity for a calculation timestep half that of the larger resolution, translating to (2) twice the number of calculations (4 x 2 = 8). The challenge for modellers is knowing what resolution is necessary to achieve results that are fit for purpose with sufficient accuracy. This Wiki page uses two test cases to discuss this topic.
 
<u>[https://tuflow.com/download/Australian_Rainfall_Runoff_Project15_TwoDimensional_Modelling_DraftReport.pdf Australian Rainfall and Runoff Guideline - Two Dimensional Modelling in Urban and Rural Floodplain]</u> provides some recommendations on this topic. It states:
''The resolution of a 2D model grid/mesh determines the scale of physical features and flow behaviour that can be modelled for a given study area. Selection of an appropriate resolution is generally driven by a combination of the following factors:
* The scale of topographic and/or flow phenomena to be modelled
* The desired level of detail to be achieved in the model outputs
* The length of event time and consequent run time
* The size of the area of interest
Details of the model schematisation process including resolution aspects are described in Chapter 6. Chapter 7 also highlights the importance of grid/mesh resolutions in achieving manageable run times to maximise calibration outcomes.
Table 10-2 (below) provides guidance on levels of model resolution that may be appropriate in certain typical situations.''
 
This Wiki page uses two test cases to discuss this topic.
 
= Test Case 1 =