WORKED EXAMPLES 623
- Choose a convenient time of travel t, which is 10 s in this example.
Obviouslytshould be small for closely packed bed contours in order
to achieve better accuracy. Draw the orthogonals or rays at A, B, C,
D... and advance these rays by cAt,cBt,cCt,cDt,... to A, B, C,
D.... - Repeat steps 2 and 3 at A, B, C, D... to advance the rays for time
t. - The lines drawn normal to the rays are the wave crests. Rays and
crests are sketched until wave breaking is reached. Refraction coeffi-
cients may be determined from the spacing of the rays and wave
heights calculated if required.
The refraction pattern for the example is shown in Fig. 14.27.
Fig. 14.27 Refraction diagram (Worked example 14.3)
Worked Example 14.4
During construction of a pier, one of the vertical steel piles, diameter
0.508 m, thickness 12.5 mm, and length equal to the depth of water of 10 m,
is subjected to a current of 0.5 m s^1. The mass of the pile is 195 kg m^1. The
modulus of elasticity is 200 109 Nm^2. The second moment of area of the
section is 6.0 10 4 m^4. The density of sea water is 1030 kg m^3.
Will this pile be subjected to flow-induced oscillations?