Pump formula (Water Overlay)

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Revision as of 14:30, 15 April 2019 by Frank@tygron.nl (talk | contribs)
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Pumps are hydraulic structures can pump water from areas with a lower water level to areas with a higher water level. A negative pump speed is also allowed. In this article we will refer to this as a drain.

The amount being pumped or drained is dependent on the water levels on both sides of the pump.

Case 1: Pump:
First the capacities are calculated.

If a positive Pump q is defined:

Qp,t = Δt * qt

If a lower threshold Tl is defined as well:

Qlth = max ( 0, wt,l - Tl,t )

If an upper threshold Tl is defined as well:

Quth = max ( 0, Tl,t- wt,u )

If a capacity Qtotal is defined:

Qc = Qtotal- ΣQ0..t-1

After calculating the capacities, the actual water pumped upwards is calculated. If any of the terms are undefined, they are not included.

Δw = max( 0 , min( Qlth,Quth , Qt , Qc ) ) / A

Where:

  • wt = The water level on at time t, relative to datum.
  • Tl,t = The LOWER_THRESHOLD attribute of the inlet at time t.
  • Tu,t = The UPPER_THRESHOLD attribute of the inlet at time t.
  • qt = INLET_Q attribute at time t.
  • Δt = Computational timestep.
  • Qtotal = The INLET_CAPACITY attribute of the inlet.
  • Q0..n = The calculated previous amounts of flow.
  • Qlth = The amount of water inflow desired based on the inlet's LOWER_THRESHOLD attribute.
  • Quth = The amount of water outflow desired based on the outlet's UPPER_THRESHOLD attribute.
  • Qt = The amount of water inflow (or outflow when negative) possible based on the INLET_Q attribute and timestep Δt.
  • Qc = The amount of water outflow possible based on the total capacity of the outlet.
  • A = Size of the Inlet/Outlet area in m2, based on the amount of cells and cell size. Current implementation only has one cell.
  • Δw = The amount of water flow which takes place.

See also

Template:WaterOverlay nav