Inlet formula (Water Overlay): Difference between revisions

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Inlets are hydraulic structures can pump water in and out of the project area and are connected with a water body outside the project area.__NOTOC__


The amount flowing in or out of inlets is calculated for the cell the inlet resides on.
''Case 1: '''Inlet''':''<br>
When calculating inlets, first the capacities are calculated.
If a lower threshold T<sub>l</sub> is defined:
: ''Q<sub>lth</sub> = max( 0 , T<sub>l,t</sub> - w<sub>t</sub> )''
If a positive Inlet q is defined:
: ''Q<sub>t</sub> = Δt * q<sub>t</sub>''
If a capacity Q<sub>total</sub> is defined:
: ''Q<sub>c</sub> = Q<sub>total</sub>''- ΣQ<sub>0..t-1</sub>
After calculating the capacities, the actual water inflow is calculated. If any of the terms are undefined, they are not included.
: ''Δw = max( 0 , min( Q<sub>lth</sub> , Q<sub>t</sub> , Q<sub>c</sub> ) ) / A''
''Case 2 '''Outlets''':''<br>
When calculating outlets, first the capacities are calculated.
If an upper threshold T<sub>u</sub> is defined:
: ''Q<sub>uth</sub> = min( 0 , T<sub>u</sub> - w<sub>t</sub> )''
If a negative Inlet q is defined:
: ''Q<sub>t</sub> = Δt * q<sub>t</sub>''
If a capacity Q<sub>total</sub> is defined:
: ''Q<sub>c</sub> = -Q<sub>total</sub> - ΣQ<sub>0..t-1</sub>''
After calculating the capacities, the actual water ouflow is calculated. If any of the terms are undefined, they are not included.
: ''Δw = min( 0 , max( Q<sub>uth</sub> , Q<sub>t</sub> , Q<sub>c</sub>) ) / A''
Where:
* w<sub>t</sub> = The water level on at time t, relative to [[Datum|datum]].
* 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.
* q<sub>t</sub> = [[Inlet q (Water Overlay)|INLET_Q]] attribute at time t.
* Δt = Computational timestep.
* Q<sub>total</sub> = The [[Inlet capacity (Water Overlay)|INLET_CAPACITY]] attribute of the inlet.
* Q<sub>0..n</sub> = The calculated previous amounts of flow.
* Q<sub>lth</sub> = The amount of water inflow desired based on the inlet's [[Lower threshold (Water Overlay)|LOWER_THRESHOLD]] attribute.
* Q<sub>uth</sub> = The amount of water outflow desired based on the outlet's [[Upper threshold (Water Overlay)|UPPER_THRESHOLD]] attribute.
* Q<sub>t</sub> = The amount of water inflow (or outflow when negative) possible based on the INLET_Q attribute and timestep Δt.
* Q<sub>c</sub> = The amount of water outflow possible based on the total capacity of the outlet.
* A = Size of the Inlet/Outlet 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.
==See also==
* [[Inlet (Water Overlay)|Inlet]]
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Revision as of 14:10, 15 April 2019