90° Triangular Sharp-Crested Weir Plate
Precision milled brass plate with 90° notch angle and 45° downstream beveled knife edge.
Agricultural Engineering / V-Notch Weir Calibration
FREE TO EXPLORELABORATORY 15 · AGRICULTURAL ENGINEERING
90° V-Notch Sharp-Crested Weir Flow Rate & Discharge Coefficient (C_d)
Calibrate a 90° V-notch sharp-crested weir in an open irrigation flume and evaluate the weir discharge coefficient C_d and proportionality constant C_w. Explore interactive farm machinery simulation, irrigation hydraulics, and agricultural engineering telemetry.
FARM MACHINERY · SOIL & WATER · POST-HARVEST · STRUCTURES
Your virtual agricultural engineering laboratory.
MEASURED WEIR DISCHARGE Q—
FIELD & TEST CELL TELEMETRY
Ready to sample with H^2.5 = 0.021 m^2.5.
Adjust H^2.5, then execute agricultural trial.
Agricultural engineering telemetry and biosystems states are evaluated rigorously using 64-bit IEEE 754 precision. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity agricultural and environmental modeling.
Agricultural assumptions and boundary condition limits
The 5/2 power law applies strictly for heads H > 0.05 m; below 5 cm, water surface tension and fluid viscosity dominate. Evaluated using a precision brass 90° V-notch plate mounted in a rectangular flume across water heads from 0.12 m to 0.28 m (H^2.5 from 0.005 to 0.045 m^2.5).
Agricultural apparatus & field instrumentation sensors.
Hydraulic Open-Channel Laboratory Flume
Recirculating water flume with wave-damping baffles and upstream calming section.
Vernier Point Gauge with Micrometer
Measures upstream water surface elevation H with 0.1 mm precision.
Primary Volumetric Gravimetric Tank
Captures discharged water over timed intervals to determine true benchmark flow rate Q.
Nappe Aeration Vent Pipes
Supplies ambient air beneath the falling nappe to prevent vacuum cling and calibration distortion.
Electromagnetic Reference Flow Meter
Monitors flume inflow rate continuously for flow stability verification.
FOLLOW THE METHOD
A reason behind every step.
Calibrate a 90° V-notch sharp-crested weir in an open irrigation flume and evaluate the weir discharge coefficient C_d and proportionality constant C_w. Standardized parameter settings: 0.005, 0.013, 0.021, 0.029, 0.037, 0.045 m^2.5.
01
Weir Zero Datum Setting
Fill the flume until water is exactly level with the vertex of the V-notch. Lower the vernier point gauge until its tip touches the meniscus at the notch vertex and record the zero datum reading H_0.
02
Calming Screen Alignment
Place mesh calming baffles 3.0 meters upstream of the weir to dissipate surface waves and establish uniform approach velocity.
03
Initial Flow Stabilization
Start the supply pump to establish an upstream head H = 0.120 m (H^2.5 = 0.0050 m^2.5), verifying that the nappe springs clear of the crest and is fully aerated.
04
Timed Volumetric Collection
Divert the weir discharge into the gravimetric weigh tank for exactly 60.0 seconds, measuring collected mass to calculate volumetric flow rate Q (m³/s).
05
Head Incrementation
Systematically increase pump flow across five additional stages up to H = 0.280 m (H^2.5 = 0.0450 m^2.5), logging H and Q for each trial.
06
Weir Coefficient Regression
Plot measured discharge Q against H^2.5, perform linear regression through the origin, and determine the Thomson weir discharge coefficient C_w and C_d.
YOUR NOTEBOOK · 0 OBSERVATIONS
Turn measurements into agricultural engineering insight.
Points are your recorded observations. The solid regression line validates V-Notch Weir Calibration mathematical scaling.
LINEAR REGRESSION FIT · y = mx + b
Q = C_w · H^2.5 = 1.3800 · H^2.5
| # | Head Raised to 2.5 Power H^2.5 (m^2.5) | Measured Weir Discharge Q (m³/s) | Head raised to 2.5 power H^2.5 (m^2.5) | Discharge Q (m³/s) | Remove |
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