Inlet formula (Water Overlay): Difference between revisions
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When calculating inlets, first the capacities are calculated. | When calculating inlets, first the capacities are calculated. | ||
If a T<sub>l</sub> is defined: | 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> )'' | : ''Q<sub>lth</sub> = max( 0 , T<sub>l,t</sub> - w<sub>t</sub> )'' | ||
If | If a positive Inlet q is defined: | ||
: ''Q<sub>t</sub> = Δt * q<sub>t</sub>'' | : ''Q<sub>t</sub> = Δt * q<sub>t</sub>'' | ||
If a capacity Q<sub>total</sub> is defined: | If a capacity Q<sub>total</sub> is defined: | ||
: ''Q<sub>c</sub> = Q<sub>total</sub>''- | : ''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. | 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 | : ''Δw = max( 0 , min( Q<sub>lth</sub> , Q<sub>t</sub> , Q<sub>c</sub> ) ) / A'' | ||
'''Outlets:'''<br> | '''Outlets:'''<br> | ||
When calculating outlets, first the capacities are calculated. | When calculating outlets, first the capacities are calculated. | ||
If | 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 | If a negative Inlet q is defined: | ||
: '' | : ''Q<sub>t</sub> = Δt * q<sub>t</sub>'' | ||
If a | 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. | After calculating the capacities, the actual water ouflow is calculated. | ||
: ''Δw = min( 0 , max( | : ''Δw = min( 0 , max( Q<sub>uth</sub> , Q<sub>t</sub> , Q<sub>c</sub>) ) / A'' | ||
: If any of the terms are undefined, they are not included. | : If any of the terms are undefined, they are not included. | ||
| Line 45: | Line 45: | ||
* Δt = Computational timestep. | * Δt = Computational timestep. | ||
* cell = Cell size. | * cell = Cell size. | ||
* A = area of the inlet/outlet | |||
* C<sub>speed</sub> = The amount of water inflow (or outflow when negative) possible based on the inlet's [[Inlet q (Water Overlay)|INLET_Q]] attribute. | * C<sub>speed</sub> = The amount of water inflow (or outflow when negative) possible based on the inlet's [[Inlet q (Water Overlay)|INLET_Q]] attribute. | ||
* C<sub>incap</sub> = The amount of water inflow possible based on the total [[Inlet capacity (Water Overlay)|capacity]] of the inlet. | * C<sub>incap</sub> = The amount of water inflow possible based on the total [[Inlet capacity (Water Overlay)|capacity]] of the inlet. | ||
Revision as of 13:23, 15 April 2019
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.
The amount flowing in or out of inlets is calculated for the cell the inlet resides on.
Inlets:
When calculating inlets, first the capacities are calculated.
If a lower threshold Tl is defined:
- Qlth = max( 0 , Tl,t - wt )
If a positive Inlet q is defined:
- Qt = Δt * qt
If a capacity Qtotal is defined:
- Qc = Qtotal- ΣQ0..t-1
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( Qlth , Qt , Qc ) ) / A
Outlets:
When calculating outlets, first the capacities are calculated.
If an upper threshold Tu is defined:
- Quth = min( 0 , Tu - wt )
If a negative Inlet q is defined:
- Qt = Δt * qt
If a capacity Qtotal is defined:
- Qc = -Qtotal - ΣQ0..t-1
After calculating the capacities, the actual water ouflow is calculated.
- Δw = min( 0 , max( Quth , Qt , Qc) ) / A
- 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.
- A = area of the inlet/outlet
- 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.
- Tl = The LOWER_THRESHOLD attribute of the inlet.
- Tu = The UPPER_THRESHOLD attribute of the inlet.