Revision as of 11:12, 20 August 2018 view source Chris Huxley (talk \| contribs) Bureaucrats, Administrators 7,785 edits →Test Case 2 - Discussion ← Older edit		Revision as of 11:13, 20 August 2018 view source Chris Huxley (talk \| contribs) Bureaucrats, Administrators 7,785 edits →Test Case 2 - Discussion Newer edit →
Line 160: * Detailed integrated 1D/2D urban modelling may adopt the 15ft (4.6m) or slightly finer 12ft (3.7m) cell resolution if the cumulative simulation time for all model events/scenarios does not adversely impact the project timeline. This timeframe consideration is particularly relevant in locations such as Australia where an ensemble methodology is currently replacing single event approaches as a way to address uncertainty associated with hydrologic assumptions. * Broad-scale quick run simulation for urban flood forecasting purposes may adopt a coarser 20ft cell resolution or investigate the suitability of a 25ft cell resolution to achieve a quicker simulation turnaround time.<br> The run time results from this test case highlight a useful relationship used by modellers who wish to estimate likely simulations times for models that use a higher resolution than that presently simulated. The simulation time trend is as follows: * A factor 2.0 increase in model resolution (eg. increasing the resolution from 30ft to 15ft) will increase the simulation time by a factor of 8.0. In basic terms this relationship is due to doubling the resolution (halving the cell size) increasing the number of cells by a factor (4) four and requiring half the timestep to maintain stability (i.e. 2 two times the number of calculations) (4x2=8). The ratios for this test case don't match the above generalised trend exactly, though are close enough to be useful when optimising the cell size to meet project requirements.<br> ~~[[File:Mesh Converge Direct Rainfall Simulation Time Factor.png\|700px]]~~

TUFLOW 2D Cell Size Selection: Difference between revisions