Civil Engineering - Hydraulics - Discussion

Discussion Forum : Hydraulics - Section 4 (Q.No. 47)
47.
For the two dimensional flow, the stream function is given by ψ = 2xy. The velocity at a point (3, 4) is
6 m/sec
8 m/sec
10 m/sec
12 m/sec
15 m/sec.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
15 comments Page 1 of 2.

Srj said:   6 years ago
For Ψ=3xy velocity=2,3.

Diff w.r.t x=3y.
Diff w.r.t y=3x.
3*2=6,
3*3=9.

√(6^2+9^2)
√(36+81)
√117.

So, the Answer is.10.82.

Triguna sethi said:   5 years ago
U=dy/dx=2y=2*4=8.
V=dy/dy=2x=2*3=6.
Ivl=lv^+u^l=l8^+6^l=l64+36l^1/2=(100)^1/2= √(100)=10.

NILESHKUMAR Mali said:   6 years ago
D/DX=2y=2x4 = 8
D/Dy=2x=2x3 = 6.

Take under root=(√8^2+6^2)= √100=10M/sec.

Priyanka said:   5 years ago
Accurate and understandable explanation. Helpful when your have some doubt.

Thank you.

Mahendra said:   1 decade ago
u = dy/dx = 2y = 2*4 = 8.
v = dy/dy = 2x = 2*3 = 6.
|v| = (8^2+6^2)^1/2 = 10.

Deepankar said:   4 years ago
@All.

U = -d(psi)/dy.

And, V= d(psi)/dx.

So that makes U = -6 and V = 8.

Nayan said:   8 years ago
Differentiate the stream function with X and Y and get value of u and v.

Niki said:   1 year ago
2x = 2 * 3 = 6.
2y = 2 * 4 = 8.
√((6)^2 + (8)^2) = 10.
(5)

Arya said:   8 years ago
How will find velocity. I got the value of u & v?

Apcivilian said:   4 years ago
You're absolutely right, Thanks @Deepankar.


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