Inlet formula (Water Overlay): Difference between revisions

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* C<sub>outthres</sub> = The amount of water outflow desired based on the outlet's [[Upper threshold (Water Overlay)|UPPER_THRESHOLD]] attribute.
* C<sub>outthres</sub> = The amount of water outflow desired based on the outlet's [[Upper threshold (Water Overlay)|UPPER_THRESHOLD]] attribute.


* WL<sub>surface</sub> The water level on the surface, relative to [[Datum|datum]].
* WL<sub>surface</sub> = The water level on the surface, relative to [[Datum|datum]].
* C<sub>total</sub> = The [[Inlet capacity (Water Overlay)|INLET_CAPACITY]] attribute of the inlet.
* C<sub>total</sub> = The [[Inlet capacity (Water Overlay)|INLET_CAPACITY]] attribute of the inlet.
* I<sub>Q</sub> = The INLET_Q attribute of the inlet.
* I<sub>Q</sub> = The INLET_Q attribute of the inlet.

Revision as of 14:08, 4 April 2019

The amount flowing in or out of inlets is calculated for the cell the inlet resides on.

When calculating inlets, first the capacities are calculated.

If a Tlower is defined:

Cinthres = max( 0 , Tlower - WLsurface )

If a IQ is defined:

Cspeed = Δt * IQ

If a Ctotal is defined:

Cincap = Cused - Ctotal

After calculating the capacities, the actual water inflow is calculated.

Δw = max( 0 , min( Cinthres , Cspeed , Cincap ) ) / cell
If any of the terms are undefined, they are not included.


When calculating outlets, first the capacities are calculated.

If a Tlower is defined:

Coutthres = min( 0 , Tupper - WLsurface )

If a IQ is defined:

Cspeed = Δt * IQ

If a Ctotal is defined:

Coutcap = -Ctotal - Cused

After calculating the capacities, the actual water ouflow is calculated.

Δw = min( 0 , max( Coutthres , Cspeed , Coutcap) ) / cell
If any of the terms are undefined, they are not included.


After the water flow (either inflow or outflow) is computed, the capacity is updated.

Cused (new) = Cused (old) + (Δw * cell)


Where:

  • Δw = The amount of water flow which takes place.
  • Δt = Computational timestep.
  • cell = Cell size.
  • Cspeed = The amount of water inflow (or outflow when negative) possible based on the inlet's INLET_Q attribute.
  • Cincap = The amount of water inflow possible based on the total capacity of the inlet.
  • Coutcap = The amount of water outflow possible based on the total capacity of the outlet.
  • Cinthres = The amount of water inflow desired based on the inlet's LOWER_THRESHOLD attribute.
  • Coutthres = The amount of water outflow desired based on the outlet's UPPER_THRESHOLD attribute.
  • WLsurface = The water level on the surface, relative to datum.
  • Ctotal = The INLET_CAPACITY attribute of the inlet.
  • IQ = The INLET_Q attribute of the inlet.
  • Tlower = The LOWER_THRESHOLD attribute of the inlet.
  • Tupper = The UPPER_THRESHOLD attribute of the inlet.

See also

Template:WaterOverlay nav