Hydraulic jump and GVF water surface.

Question 1

What are the engineering importance of hydraulic jumps?

Answer 1

Dissipates energy of high velocity water.
Reduces downstream erosion
40% -60% flow energy can be dissipated
highly fluid mixing can be used for water and sewage treatment.

Question 2

what is the Hydraulic jump equation?

Answer 2

P1 = rho*g*hcentre1*A1
P2 = rho*g*hcentre2*A2

so,
(rhoQ^2)/A1 + rhoghcentre1A1
=
(rhoQ^2)/A2 + rhoghcentre2A1

Question 3

What is the Conjugate depth formula in rectangular channel?

Answer 3

h2 = h1/2 * (sqrt(1+8Fr^2) - 1)
or
h1 = h2/2 * (sqrt(1+8Fr^2) - 1)

Question 4

What happens to the jump strength when the Fr number gets higher?

Answer 4

The jump becomes more turbulent and more energy is dissapated.

Question 5

What should the Ljump / h2 ratio be?

Answer 5

4 < Ljump / h2 < 6

Question 6

how to calculate the efficiency of a jump?

Answer 6

n = /\E / E1 * 100

(h2 + V2^2/2g) -(h1 + V1^2/2g)) / (h1 + V1^2/2g

Question 7

What variables are in the backwash calculation?

Answer 7

h, A, X, R, C, V, E, /\E, V_, R_, C_, J_, /\s, sum(/\s).

Question 8

What does:
V_ = 
R_ =
C_ = 
J_ =

Answer 8

V_= (V1 +V2)/2
R_= (R1 +R2)/2
C_= (C1 +C2)/2  (C = 1/n * R^1/6)
J_ = V_^2 / (C_^2 * R_)

(V_ doesn’t = Q/ A_)

Question 9

Whats does dh/dx = ?

What does it mean?

Answer 9

(i - J) / (1 - Fr^2)
dh/dx > 0 - water increasing
dh/dx < 0 - water decreasing
dh/dx = 0 - uniform flow
dh/dx = i - then staying level
dh/dx = infinity - shooting up or down

Question 10

What are the M types of water flow?

Answer 10

M —-> i < ic
M1 flow is above critical and uniform
M2 flow is above critical but below uniform
M3 flow is below both circle and uniform

Question 11

What are the S types of flow?

Answer 11

S —-> i > ic
S1 = flow is above critical and uniform
S2 = flow is above uniform but below critical
S3 = Flow is below both critical and uniform

Question 12

What are the C types of flow?

Answer 12

C —-> i = ic
C1 = flow is above both critical and uniform
C3 = flow is below both critical and uniform

Question 13

What are the H types of flow?

Answer 13

H —-> i = 0
H1 = flow is above both critical and uniform
H3 = flow is below both critical and uniform

Question 14

What are the A types of flow?

Answer 14

A —-> i < 0
A2 = flow is above both critical and uniform
H3 = flow is below both critical and uniform