USGS - Guide for Selecting Manning's Roughness Coefficients for Natural Channels and Flood Plains
Copy of flow, slope &pipe dia. calculation using manning's formula (2).xls
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Transcript of Copy of flow, slope &pipe dia. calculation using manning's formula (2).xls
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8/18/2019 Copy of flow, slope &pipe dia. calculation using manning's formula (2).xls
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Manning's formula
v = cross-sectional mean velocity (m/s)
R = hydraulic radius A/P (m)
S = slope of pipe (m/m)
Q= A * 1/n * R 2/3 * S 1/2
V = 1/n * R 2/3 * S 1/2
S = (V * n * R -2/3)2
D = (6.42 *Qn /S 1/2)3/8
Q = volume flow =V*A (m3 /s)
n = Manning coefficient of roughness
A = cross sectional area of flow (m2)P = wetted perimeter (m)
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Calculation
IN!"S #!"!"
Pipe Diameter (inch) ₌ 4
₌ $% ₌ %.%%%%
n ₌ %.%11
V (&t/') ₌ %.%%
slope () ₌ %
₌!"!!#$
P (m)₌
!"$%&'
(m)₌
!"!2%#
Q= A * 1/n * R 2/3 * S 1/2 V = 1/n * R 2/3 * S 1/2
Percent of (or ratio to) full depth ($!! ifflowing full) = (!$!!)
Q (3 /')
A (m2)
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Calculation
IN!"S #!"!"
Pipe Diameter (inch) ₌ 8 S () ₌ %.%%%
₌ %
n ₌ %.%11
velocity (ft/s) ₌ %
₌!"!2#2
P (m)₌
!"#!2*
(m)₌
!"!'!2
S = (V * n * R -2/3)2
Percent of (or ratio to) full depth ($!! ifflowing full) = (!$!!)
A (m2)
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+n case of half flow
Calculation
IN!"S #!"!"
n ₌ %.%11 D (in) ₌ +DIV/%,
₌ %.%%%%
V (&t/') ₌ +DIV/%,
slope () ₌ %
₌!"!2#2
P (m)₌
!"#!2*
(m)₌
!"!'!2
D = (6.42 *Qn /S 1/2)3/8
,(m/s)
A (m2)
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0aulic Raiu' o& a0tiall ill Ci0cula0 Conuit' (i')
Inut' to calculat 'lo
Percent filling of pipe = .!
Pipe +nside Diameter d = 2!"2 mm
Calculation'
Pipe adius r = !"$!$' m
0low Depth h = !"!'!&'
1entral Angle = 2"$&
1ircular 3egment Area 4 = !"!!*2
Arc 5ength s = !"2%' m
0low Area A = !"!2#2
!"#!2* m
!"!'!$&% m
Inut' to calculat QVPercent filling of pipe = %!
Pipe +nside Diameter d = $!$"' mm
Calculation'
Pipe adius r = !"!%!* m
0low Depth h = !"!%!*
1entral Angle = "$#2
1ircular 3egment Area 4 = !"!!#$
Arc 5ength s = !"$%&' m
0low Area A = !"!!#$
!"$%&' m!"!2%# m
m2
m2
6etted Perimeter P6
=
7ydraulic adius 7 =
m2
m2
6etted Perimeter P6
=
7ydraulic adius 7 =
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0aulic Raiu' o& a0tiall ill Ci0cula0 Conuit' (i')
lo5 Dt7 0
1ircular 3egment Area 1ircular 3egment Area
Arc 5ength Arc 5ength
0low Area 0low Area
6etted Perimeter 6etted Perimeter
7ydraulic adius 7ydraulic adius
lo5 Dt7 90
θ
4
r
s
r
h
s
4
θ
θ
h
r
4
θ=2arccos
(r−h
r )
k =r2 (θ−Sinθ )
2
s=r×θ
A=k
PW =s
R H =
A
Pw
θ=2arccos
(r−h
r )
k =r2 (θ−Sinθ )
2
s=r×θ
A =πr 2−k
PW =2πr −s
R H =
A
Pw
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Su0&ac :at0ial
:annin;
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3teel - ew unlined !"!$$
3teel - iveted !"!$&
?itrified 3ewer !"!$ - !"!$%
6ood - planed !"!$2
6ood - unplaned !"!$
6ood stove pipe small diameter !"!$$ - !"!$2
6ood stove pipe large diameter !"!$2 - !"!$
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