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Line 8: 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. <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: <br> : ''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: <br> : ''* 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.'' ~~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.

TUFLOW 2D Cell Size Selection: Difference between revisions