Find the rate of flow and conveyance for a rectangular channel `7.5 m` wide for uniform flow at a depth of `2.25 m`. The channel is having bed slope as 1 in 1000. Take Chezyâ??s constant `C = 55`. Also state whether the flow is tranquil or rapid.
Solution:
Width of the rectangular channel, b=7.5m'>b=7.5mb=7.5m
Depth of flow, y=2.25m'>y=2.25my=2.25my=2.25m
Bed slope, S0'>S0S0S0 =11000'>110001100011000
Chezy's constant, C=55'>C=55C=55C=55
Now, we have,
Rate of flow, Q=A??V=A??CR??S0.......(I)'>Q=A??V=A??CR??S0????????????.......(I)Q=A??V=A??CR??S0????????????.......(I)Q=A??V=A??CR??S0????????????.......(I)
Where, Flow area, A=b??y=7.5??2.25=16.875m2'>A=b??y=7.5??2.25=16.875m2A=b??y=7.5??2.25=16.875m2A=b??y=7.5??2.25=16.875m2
Wetted perimeter, P=b+2y=7.5+2??2.25=12.0'>P=b+2y=7.5+2??2.25=12.0P=b+2y=7.5+2??2.25=12.0P=b+2y=7.5+2??2.25=12.0
Also,
hydraulic radius, R=AP=16.87512.0=1.406'>R=AP=16.87512.0=1.406R=AP=16.87512.0=1.406R=AP=16.87512.0=1.406
Thus from equation (I)'>(I)(I)(I),
Q=A??V=A??CR??S0=16.875'>Q=A??V=A??CR??S0????????????=16.875Q=A??V=A??CR??S0????????????=16.875Q=A??V=A??CR??S0????????????=16.875??....
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Solution:
Width of the rectangular channel, b=7.5m'>b=7.5m
Depth of flow, y=2.25m'>y=2.25my=2.25my=2.25m
Bed slope, S0'>S0S0S0 =11000'>110001100011000
Chezy's constant, C=55'>C=55C=55C=55
Now, we have,
Rate of flow, Q=A??V=A??CR??S0.......(I)'>Q=A??V=A??CR??S0????????????.......(I)Q=A??V=A??CR??S0????????????.......(I)Q=A??V=A??CR??S0????????????.......(I)
Where, Flow area, A=b??y=7.5??2.25=16.875m2'>A=b??y=7.5??2.25=16.875m2A=b??y=7.5??2.25=16.875m2A=b??y=7.5??2.25=16.875m2
Wetted perimeter, P=b+2y=7.5+2??2.25=12.0'>P=b+2y=7.5+2??2.25=12.0P=b+2y=7.5+2??2.25=12.0P=b+2y=7.5+2??2.25=12.0
Also,
hydraulic radius, R=AP=16.87512.0=1.406'>R=AP=16.87512.0=1.406R=AP=16.87512.0=1.406R=AP=16.87512.0=1.406
Thus from equation (I)'>(I)(I)(I),
Q=A??V=A??CR??S0=16.875'>Q=A??V=A??CR??S0????????????=16.875Q=A??V=A??CR??S0????????????=16.875Q=A??V=A??CR??S0????????????=16.875??'>??????551.406??11000'>551.406??11000??????????????????????551.406??11000??????????????????????551.406??11000??????????????????????
or, Q=34.76m3sec'>Q=34.76m3secQ=34.76m3secQ=34.76m3sec
Also, Conveyance,K=A??cR=16.875'>K=A??cR??????=16.875K=A??cR??????=16.875K=A??cR??????=16.875??'>??????55'>555555??'>??????1.406'>1.406??????????1.406??????????1.406??????????=1100.5'>=1100.5=1100.5=1100.5
Again, Froude's number, Fr=Vg??y=C??R??S09.81??2.25=0.438'>Fr=Vg??y??????????=C??R??S0????????????9.81??2.25??????????????????=0.438Fr=Vg??y????????=C??R??S0????????????9.81??2.25??????????????????=0.438Fr=Vg??y??????????=C??R??S0????????????9.81??2.25??????????????????=0.438
Since froudes number,Fr'>FrFrFr is less than 1'>111, the flow in the channel is of tranquil in nature.
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