Civil Engineering - Waste Water Engineering - Discussion

Discussion Forum : Waste Water Engineering - Section 1 (Q.No. 10)
10.
The width of a rectangular sewer is twice its depth while discharging 1.5 m/sec. The width of the sewer is
0.68 m
0.88 m
1.36 m
1.76 m.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
30 comments Page 1 of 3.

Jinish said:   6 years ago
Take v= 1.62 m/sec.

B=2 D.
Q=AxV.
A= B * D.
A= 2 *D * D = 2D^2.

So Q=AxV and Q = 1.5 m/sec.
1.5= 2D^2 * 1.62.
1.5/1.62= 2D^2.
1.5/ 1.62*2 = D^2,
D= .68m.
B= 2D = 2*0.68 = 1.36 m.
(6)

Emon khan said:   5 years ago
Develop a relation between a diameter of the circular section of a sewer and a side of the rectangular sewer section having width as twice its depth, the three sides being wetted.
(5)

Jurgis said:   1 decade ago
Sewers are never running full, however the answer relates to full pipe discharge. And it is not really correct to relate the unit "m/sec" to discharge as this relates to velocity.

Lakha said:   1 decade ago
For sewer velocity is 0.9m/sec to 0.75. So Q = AV.

Given b =2d and Q = 1.5.
Then A = Q/v, bd = 1.5/0.9 = 1.67.

(2d)d = 1.67, d = 0.91.
Hence b = 2(0.91) = 1.82 m.

Ramgopal Sahu said:   8 years ago
Considering minimum velocity for effective flow I.e, 0.45m/sec.

A =Q/V => 1.5/0.45=3.333.
Area (A) => width b=2d , depth = d.
A= (2d)*d = 3.333.
d = 1.29m.
(1)

Roy said:   8 years ago
Assume velocity of flow as 1m/s given discharge Q= 1.5m3/s A=Q/V WIDTH=2HEIGHT, b *h=2h * h=2h^2=Q//v=1.5/1, h=0.88, W=1.36.

Adhi said:   9 years ago
They have given velocity value 1.5m/s.

Unit of velocity=m/s. And data is insufficient to solve, so please help me.

DHAWAL KALRA said:   1 decade ago
Here we can't assume the velocity direct as designing of sewer relates to max and min conditions of flow.

Rajmohan said:   10 years ago
I think they have to give slope of channel & manning constant then only we can approach to solve.

Sahab said:   7 years ago
Let setling velocity = 1.0 m/sec.
Q = A.V (b=2h given)
A = Q/V.
b * (b/2) = 1.5/1.0,
B = 1.73m.


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