Civil Engineering - GATE Exam Questions - Discussion

Discussion Forum : GATE Exam Questions - Section 2 (Q.No. 38)
38.
Three reservoirs A, B and C are interconnected by pipes as shown in the below figure Water surface elevations in the reservoirs and the Piezometric Head at the junction J are indicated in the below figure.

Discharges Q1, Q2 and Q3 are related as
Q1 + Q2 = Q3
Q1 = Q2 + Q3
Q2 = Q1 + Q3
Q1 + Q2 + Q3 = 0
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
9 comments Page 1 of 1.

Sneha Mathai said:   4 years ago
Ans is option A.

Flow takes place from higher energy level to lower energy level.
Head for A, 200m > head at jn, 160m
So flow from A to jn.

Head for B, 180m > head at jn, 160m
So flow from B to jn.

Head for C, 140m < head at jn, 160m
So flow from jn to C.

Hence, Q1 + Q2 = Q3.

NILADRI ROY said:   4 years ago
Q1+Q2=Q3.

ABHISHEK RAAZ said:   4 years ago
At junction point J velocity head will be zero so total head at J will be 160 m. The total head at A=200m and total head at B=180m and total head at C=140 m. Now you can judge flow condition from higher energy levels to lower levels.

Dipesh said:   5 years ago
But piezometer level only shows p/(density)g + z.

It doesn't show v^2/2g. So it's not total head then how can we make judgement without velocity head?

Saini said:   5 years ago
Option A is correct. I also agree.

Yogesh said:   6 years ago
Option A is correct.

Q1 takes place from 200 to J (160),
Q2 takes place from 180 to J (160),
Q3 takes place from J (160) to 140.

So Q3 = Q1 + Q2.

Radhika said:   7 years ago
Flow always takes place from higher energy level to the lower level.

Hence [B] is correct.

Khatana said:   8 years ago
No, when head at junction-less than B then how it will fill B option A?

VENKATESH said:   1 decade ago
If we take datum at bottom of tank C we conclude that tanks A, B, and C have heads 200m, 180m, 140m respectively but at junction we have some elevation head w.r.t datum and in addition piezometric head of 160m given which may be more than total heads of B, and C so water flows from A to B and C.

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