Problem

What factors contribute to length of time it takes for a model to run a 2D analysis in SewerGEMS, CivilStorm, and OpenFlows FLOOD?

Solution

Size of the grid

This will define the total number of grid cells. A large grid will typically mean more grid cells, and longer model run time.

Grid resolution

This is related to size of the individual grid cells. With smaller grid cells, the model will take longer to compute. 

Water depth

The 2D solver in the OpenFlowsFLOOD  products dynamically adjusts its time step to guarantee numerical stability. Water depth is the variable that determines if the integration time step needs to be adjusted. The higher the water depth (at any cell in the grid), the small the time step needs to be. The smaller the time step, the more time it takes to compute the simulation.

If you are simulating areas where the water depth gets too high then it will take longer to compute. Sometimes your terrain model can have errors (inconsistent values) that create unreal depressions, where water can accumulate and cause the model to slow down. Also, if you set closed boundary conditions on 2D grid(see options Impose water level in module RunOff), the water may accumulate at the open boundary and start to increase the water depth and slow the calculations. You In OpenFlows FLOOD, see options Impose water level in module RunOff, In OpenFlows FLOOD, you can also check the HDF5 results even if the simulation hasn't finished.

See Also

OpenFlows FLOOD TechNotes and FAQs

2D Modeling in SewerGEMS and CivilStorm