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Next: Capillary waves Up: Special cases Previous: Centered disturbances

Short gravity waves

For this case

displaymath5581

displaymath5583

so (1.33) yields

displaymath5585

and (1.34) yields

displaymath5587

These are sufficiently simple that one can obtain tex2html_wrap_inline5589 explicitly. From (1.36)

displaymath5591

which implies that the local wave length tex2html_wrap_inline5593 increases with x and decreases with t. Taking the arbitrary phase constant b = 0, (1.37) and (1.38) yield

displaymath5601

so

displaymath5603

which corresponds to a relation given in Art. 238 in Lamb's Hydrodynamics, but arrived at in quite a different manner.

Let n = tex2html_wrap_inline5607 , which when restricted to the ordinal numbers 1, 2, 3, tex2html_wrap_inline5609 identifies a given wave crest. From (1.39) we find that

displaymath5611

Contours of the wave crests n = 5 to 40 are plotted in Fig. 1 using this relation. The units of x and t in this plot are taken such that tex2html_wrap_inline5619 = 1. For example, if x has units of 100 m, then t has units of 16 seconds tex2html_wrap_inline5625 .


next up previous contents
Next: Capillary waves Up: Special cases Previous: Centered disturbances

Steve Baum
Sun May 19 00:59:05 CDT 1996