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 an Inlet q is defined:
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>t-1</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<sub>i</sub>''
: ''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 a T<sub>lower</sub> is defined:
If an upper threshold T<sub>u</sub> is defined:
: ''C<sub>outthres</sub> = min( 0 , T<sub>upper</sub> - WL<sub>surface</sub> )''
: ''Q<sub>uth</sub> = min( 0 , T<sub>u</sub> - w<sub>t</sub> )''


If a I<sub>Q</sub> is defined:
If a negative Inlet q is defined:
: ''C<sub>speed</sub> = Δt * I<sub>Q</sub>''
: ''Q<sub>t</sub> = Δt * q<sub>t</sub>''


If a C<sub>total</sub> is defined:
If a capacity Q<sub>total</sub> is defined:
: ''C<sub>outcap</sub> = -C<sub>total</sub> - C<sub>used</sub>''
: ''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( C<sub>outthres</sub> , C<sub>speed</sub> , C<sub>outcap</sub>) ) / cell''
: ''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.


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* 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.

See also

Template:WaterOverlay nav