Page 302 - Fundamentals of Ocean Renewable Energy Generating Electricity From The Sea

Other Aspects of Ocean Renewable Energy Chapter | 10 287

FIG. 10.9 Effect of tidal currents on wave height and wave power using a simplified method [25].
Note that opposing currents have negative speed. (A) Effect of currents on wave height. (B) Effect
of currents on wave power.

Using the conservation of wave action, we can assess the effect of tidal
currents and tidal elevations (water depth) on wave properties. For instance, for
linear monochromatic waves, and assuming the deep water approximation for
the dispersion relation (i.e. C = g/ω), the effect of currents on wave height can
be estimated as [25]
P * σ 2u σ −1 σ u 1/2 −1
= 1 + ; = 2 1 + 1 + 4 (10.5)
P ω C ω ω C
*
where P is the wave power in the presence of currents. Fig. 10.9 demonstrates
how wave height and wave power are affected by opposing or following currents