Partially full pipe (Manning) calculator

Inputs in the worked example

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Worked example — results

• ✓ Capacity ≥ design
• ✓ Self-cleansing V ≥ 0.6 m/s

Method, formulas and assumptions

• Central angle θ = 2 acos(1 − 2y/D) = 2*ACOS(1-2*0.7) = 3.9646 rad
• A = D²(θ − sinθ)/8 = (600/1000)^2*(3.9646-SIN(3.9646))/8 = 0.2114 m²
• P = Dθ/2 = 600/1000*3.9646/2 = 1.1894 m
• Q = 0.2114*(0.2114/1.1894)^(2/3)*SQRT(1/100)/0.013*1000 = 514.07 L/s
• V = 514.07/1000/0.2114 = 2.4317 m/s
• Full-bore Q = PI()*(600/1000)^2/4*(600/4000)^(2/3)*SQRT(1/100)/0.013*1000 = 614.01 L/s

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