Presentation Hydraulics Weirs
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Transcript of Presentation Hydraulics Weirs
Team advisors :Anne GADEKE &Tamas
KRAMER
Team leader :Ricardo SANTAELLA
February 2011February 2011
Weir characteristics and equations
Mike11 formulationsType of Weirs and equationsSensitivity of coefficients
ISIS formulations
Type of Weirs and equationsSensitivity of coefficients
Comparison of results: Mike11 vs. ISIS
Conclusions
Presentation OutlinePresentation Outline
Weir CharacteristicsWeir CharacteristicsBroad-crested weirs
Transversal structures to the flow
Control of donwstream water level
Flow over the structure
Critical conditions induced
Low velocities upstream, flow acceleration downstream.
Hydraulic discontinuity (Freeflow)
Critical energy – Critical depthDirect relation Discharge ->
Depth
Weir EquationsWeir Equations
Mike11 Weir FormulationMike11 Weir Formulation
Under this formulation:C1= (1.2 – 1.705)
Broad-crested Honma Formula
Mike11 Sensitivity analysisMike11 Sensitivity analysis
ISIS Weir FormulationISIS Weir Formulation
Free-flow condition
Drowned condition
Under this formulation:
Cv Cd= (0.7 – 0.95)
Under this formulation:
Cv Cd= (0.7 – 0.95)
ISIS Sensitivity analysisISIS Sensitivity analysis
Comparison Mike11 vs ISISComparison Mike11 vs ISIS
ConclusionsConclusions Every software defines weirs equations using specific formulas/coefficients.
The theory behind weir behavior is the same (Energy equation – critical conditions), thus coefficients are related between them.
Under free-flow conditions, changes in the weir coefficients influence only conditions upstream the structure.
In general a higher coefficient defines a more effective weir, therefore smaller water level to convey a given discharge.
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