Pump formula (Water Overlay): Difference between revisions
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* T<sub>l,t</sub> = The LOWER_THRESHOLD attribute of the inlet at time t. | * T<sub>l,t</sub> = The LOWER_THRESHOLD attribute of the inlet at time t. | ||
* T<sub>u,t</sub> = The UPPER_THRESHOLD attribute of the inlet at time t. | * T<sub>u,t</sub> = The UPPER_THRESHOLD attribute of the inlet at time t. | ||
* q<sub>t</sub> = [[ | * q<sub>t</sub> = [[Pump q (Water Overlay)|PUMP_Q]] attribute at time t. | ||
* Δt = Computational timestep. | * Δt = Computational timestep. | ||
* Q<sub>total</sub> = The [[Inlet capacity (Water Overlay)| | * Q<sub>total</sub> = The [[Inlet capacity (Water Overlay)|PU_CAPACITY]] attribute of the inlet. | ||
* Q<sub>0..n</sub> = The calculated previous amounts of flow. | * Q<sub>0..n</sub> = The calculated previous amounts of flow. | ||
* Q<sub>l,t</sub> = The amount of water | * Q<sub>l,t</sub> = The desired amount of water at the entry based on the pump's [[Lower threshold (Water Overlay)|LOWER_THRESHOLD]] attribute. | ||
* Q<sub>u,t</sub> = The amount of water | * Q<sub>u,t</sub> = The desired amount of water at the exit based on the pump's [[Upper threshold (Water Overlay)|UPPER_THRESHOLD]] attribute. | ||
* Q<sub>t</sub> = The amount of water | * Q<sub>t</sub> = The amount of water pumped (or drained when negative) possible based on the INLET_Q attribute and timestep Δt. | ||
* Q<sub>c</sub> = The amount of water | * Q<sub>c</sub> = The maximum amount of water flow based on the total capacity of the outlet. | ||
* A = Size of the | * A = Size of the Entry/Exit area in m<sup>2</sup>, based on the amount of cells and cell size. Current implementation only has one cell. | ||
* Δw = The amount of water flow which takes place. | * Δw = The amount of water flow which takes place. | ||
Revision as of 14:57, 15 April 2019
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: Pumping:
First the capacities are calculated.
If a positive Pump q is defined:
- Qp,t = Δt * qt
If a lower threshold Tl,t is defined as well:
- Ql,t = min ( 0, wl,t - Tl,t )
If an upper threshold Tu,t is defined as well:
- Qu,t = max ( 0, Tu,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( Ql,t , Qu,t , Qt , Qc ) ) / A
Case 2: Draining:
First the capacities are calculated.
If a negative Pump q is defined:
- Qp,t = Δt * qt
If a lower threshold Tl,t is defined as well:
- Ql,t = max ( 0, wl,t - Tl,t )
If an upper threshold Tu,t is defined as well:
- Qu,t = min ( 0, Tu,t- wt,u )
If a capacity Qtotal is defined:
- Qc = Qtotal - abs ( 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 , max( Ql,t , Qu,t , Qt , -Qc ) ) / A
Where:
- wt,l = The water level at the lower water level entry on at time t, relative to datum.
- wt,u = The water level at the upper water level entry 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 = PUMP_Q attribute at time t.
- Δt = Computational timestep.
- Qtotal = The PU_CAPACITY attribute of the inlet.
- Q0..n = The calculated previous amounts of flow.
- Ql,t = The desired amount of water at the entry based on the pump's LOWER_THRESHOLD attribute.
- Qu,t = The desired amount of water at the exit based on the pump's UPPER_THRESHOLD attribute.
- Qt = The amount of water pumped (or drained when negative) possible based on the INLET_Q attribute and timestep Δt.
- Qc = The maximum amount of water flow based on the total capacity of the outlet.
- A = Size of the Entry/Exit 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.