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Coastal Engineering: Theory and Practice
From the wave tables,
dh T
db
2.07
— = 0.04612 => b = Q 04612 = 0.04612 “
Cb = y =
= 4.488 m/sec,
Lo
156
,
Co = T = lô- = 15,6 m/sec’
From Snell’s Law,
sincto _ Cq sin39° _ 15.6
sinctf,
Cb ' sinctb
4.488
=> ab = 10°
Longshore energy flux factor is given by
Pis = Pib = ^itfCbSÏnïab
1b
=
x (1025 x 9.81) x (1.616)2 x (4.488) x sin2(10°) = 2519 N/sec
Similarly,
(b) Ho = 1.5 m, q0 = 39°, m = 1:50, T = 10 sec
Longshore energy flux factor = 6315 N/sec
(c) Hq = 1 m, cto = 39°, m = 1:50, T — 15 sec
Longshore energy flux factor = 3371 N/sec
(d) Hq = 1 m, Q0 = 58.5°, m = 1:50, T = 10 sec
Longshore energy flux factor = 3458 N/sec
(e) Ho = 1 m, Q0 = 60°, m = 1:50, T = 10 sec
Longshore energy flux factor = 3548 N/sec
From above, it is clear that increase in wave height increases Pis va^ue
significantly. The increase in wave period and the angle also changes the
value of Pis parameter.