Mode (Water Overlay): Difference between revisions

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m (Rudolf@tygron.nl moved page Calculation preference formula (Water Overlay) to Mode (Water Overlay) over redirect: Not a formula, but does affect calculation)
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This configuration option is no longer used.
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===Timesteps===
The mode of the [[Water Overlay]] affects the taken time steps, and with it the evaluation frequency, for ground water and hydraulic structures of the simulation.  
This settings influence the timesteps for rain, surfaceflow and groundwater in the calculation model.
 
All settings result in stable solution, however small fluctuations can occur in the hydro-graphs.  
Surface water simulation time steps are only depended on this mode when [[Surface_water_(Water_Overlay)|surface water]] mode is set to the '''Avg Waterway''' or '''Avg Terrain'''.
By default Speed is selected, only change this when your use-case demands it.
 
It does not influence the evaluation frequency of the surface water simulation when [[Surface_water_(Water_Overlay)|surface water]] is set to the '''Shallow''' or '''Hybrid''' mode.


* Speed: Larger timesteps (default).
===Modes===
* Normal: Average mode between Speed an Accuracy.
There are three modes available:
* Accuracy: Smallest timesteps, smoothest hydro-graphs.


===Low Impulse Mode===
* Speed: Lowest frequencies, fastest calculations. Mode factor 3.
By default the model uses full impulse to simulate waterflow. However when using long term average calculations (e.g. groundwater year round) the (short term) impulse has a very limited effect on the outcome. In this case select the Low Impulse Mode option which reduces gravity in your simulation and thus the impulse. This means that peak velocity in heavy rain-showers or floodings are not accurate, but the average waterflow through the system remains the same.
* Normal: Average mode between Speed an Accuracy. Mode factor 2.
* Accuracy: Highest frequencies, greatest detail in water movements. Mode factor 1.


The low impulse mode will reduce the used [[gravity (Water Overlay)|gravitational constant]] to 0,5.
===Timesteps===
The cell size is defined by dx. The timesteps are in seconds.


Warning: Do not use this option with floodings or heavy rain-shower stress calculations.
The mode has the following effects on timesteps:
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* Horizontal groundwater timestep = min ( 5 * dx * modeFactor , 120 )
* Vertical groundwater timestep is based on whether shallow water simulation is selected.
** Shallow water active: 2 * modeFactor.
** Shallow water not active: Horizontal groundwater timestep
* Structures and features:
** Average areas mode: 0.5 * Vertical groundwater timestep
** No average areas: 1.0 * Vertical groundwater timestep


{{WaterOverlay formula nav}}
{{WaterOverlay formula nav}}

Latest revision as of 09:59, 11 February 2022

This article is a stub.

The mode of the Water Overlay affects the taken time steps, and with it the evaluation frequency, for ground water and hydraulic structures of the simulation.

Surface water simulation time steps are only depended on this mode when surface water mode is set to the Avg Waterway or Avg Terrain.

It does not influence the evaluation frequency of the surface water simulation when surface water is set to the Shallow or Hybrid mode.

Modes

There are three modes available:

  • Speed: Lowest frequencies, fastest calculations. Mode factor 3.
  • Normal: Average mode between Speed an Accuracy. Mode factor 2.
  • Accuracy: Highest frequencies, greatest detail in water movements. Mode factor 1.

Timesteps

The cell size is defined by dx. The timesteps are in seconds.

The mode has the following effects on timesteps:

  • Horizontal groundwater timestep = min ( 5 * dx * modeFactor , 120 )
  • Vertical groundwater timestep is based on whether shallow water simulation is selected.
    • Shallow water active: 2 * modeFactor.
    • Shallow water not active: Horizontal groundwater timestep
  • Structures and features:
    • Average areas mode: 0.5 * Vertical groundwater timestep
    • No average areas: 1.0 * Vertical groundwater timestep