Ursell Number
Ursell number, abbreviated as U, a dimensionless number, indicates the nonlinearity of long surface gravity waves on a fluid layer.
Ursell Number formula |
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\(\large{ U = \frac {H} {h} \; \left( \frac {\lambda} {h} \right)^2 = \frac {H \; \lambda^2} {h^3} }\) | ||
Symbol | English | Metric |
\(\large{ U }\) = Ursell number | \(\large{dimensionless}\) | |
\(\large{ h }\) = mean water depth | \(\large{ft}\) | \(\large{m}\) |
\(\large{ H }\) = the wave height, the difference between the elevations of the wave crest and trough | \(\large{ft}\) | \(\large{m}\) |
\(\large{ \lambda }\) (Greek symbol lambda) = the wavelength, which has to be large compared to the depth, \(\large{\lambda \gg h}\) | \(\large{ft}\) | \(\large{m}\) |