Civil Engineering - Hydraulics - Discussion

Discussion Forum : Hydraulics - Section 1 (Q.No. 15)
15.
Critical depth (h) of a channel, is
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
24 comments Page 1 of 3.

Laxman said:   3 years ago
Froudes number= Inertia Force/viscous force.

F= V/(gy)^0.5.
For channel flow to be critical (Fr=1).
Now, 1= V/(gy)^0.5.

=>. (gy)^0.5 = V
=>. gy = V^2
=>. y= V^2/g.

Thus, Option A is correct.
(9)

Rohit said:   3 years ago
@Nitesh.

Thanks for explaining the answer.

M. Shaikh said:   3 years ago
As per Froude Number (Fr):

If Fr < 1 then flow is Sub-Critical flow.
If Fr > 1 then flow is Super-Critical flow,
If Fr = 1 then flow is Critical flow,

So, The formula of Fr is:
Fr = v / ( g d) ^ 1/2.
For critical depth put Fr = 1 and solve for d.
1 = v / ( g d) ^ 1/2,
(g d) ^1/2 = v.

Squaring on Both Sides;
(g d) = v ^2.
d (critical) = (v ^2)/g.
(6)

Sanjay Panchal said:   5 years ago
Thanks.
(1)

Sudip Timalsena said:   5 years ago
Thank you @Prassy.

Prassy said:   5 years ago
hc=( q2/g)^1/3.

Taking cube on both sides hc^3= q2/g.

q=Q/b= A*V/b= (b*h*V)/b= (h*v),
hc^3= (hc * V)^2/g,
hc= V2/g.

Priyanka Shah said:   6 years ago
Thank you @Nitesh.

Amare yihunie said:   7 years ago
For critical flow type specific energy = yc + v2/2g.
for rectangular channel = Ec = 1.5 yc.
1.5 yc = yc + v2/2g,
0.5 yc = v2/2g,
yc = v2/g.

Anurag said:   7 years ago
I think [q^2/g]^[1/3].

Thundir said:   7 years ago
E = y + v^2/2g is specific energy.
Here, v^2/2g is KINETIC energy and "y" is POTENTIAL energy.
So, the given answer is correct.
(1)


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