250
5 Wave Evolution in Non-uniform Currents in Deep Water
Estimation of current influence on wind wave distribution functions. The problem of the influence of current on the regime-climatic functions of the wave parameters is still incompletely investigated. However, it is
of great practical importance. The regime functions allow obtaining the wave
parameters used directly in engineering practice.
Using the aforementioned results, an attempt is undertaken to estimate
the influence of strong tidal currents in the White Sea on the regime functions
of mean wave heights in the small probability range (Korobov & Lavrenov,
1989). It should be noted that there is a regular semi-diurnal tide with current
velocities up to 250-270 cms- 1 . In order to do this it is divided into regions
according to the prevailing role of one of two possible current influence mechanisms on the wave generation or transformation. As the estimation shows,
the diagrams of regime functions, with currents taken into account, are displaced relative to the diagrams for calm water conditions towards larger wave
heights. The estimates of the calculated wave heights appear to increase by
14-16 per cent in sea regions with strong tides.
As far as the problem of current influence on the distribution of wave elements within a quasi-stationary range is concerned, this still remains open.
At least it is well known that currents can significantly change the distribution functions of wave heights and lengths. The proportion of wave heights
and lengths greater than the mean values is decreased according to the experimental data (Krivoshey, 1976). In addition, the variation and asymmetry
coefficients are considerably changed (Mass et al., 1988). Observations in natural conditions show that the currents significantly change the distribution
function of wave heights and periods (Matushevskiy, 1985).
An estimation of wave elements of prescribed probability is performed on
the basis of the mean wave height using a distribution function. The wave
height distribution function is known to be subordinate to the Rayleigh law
for all stages of wave development. The distribution function of wave elements
in deep water is dependent on the non-dimensional fetch (Krylov et al., 1976).
This assumption is confirmed by field and laboratory experiments.
Using these results, the distribution function for the case of the influence
of current on the wave generation was estimated by Mass et al. (1990). The
current and the fetch restriction by a coastline are taken into account using
the effective fetch length. It is assumed that the wave height distribution
function preserves its form and is determined by the effective fetch:
(5.155)
where
10 3
5 Wave Evolution in Non-uniform Currents in Deep Water
Estimation of current influence on wind wave distribution functions. The problem of the influence of current on the regime-climatic functions of the wave parameters is still incompletely investigated. However, it is
of great practical importance. The regime functions allow obtaining the wave
parameters used directly in engineering practice.
Using the aforementioned results, an attempt is undertaken to estimate
the influence of strong tidal currents in the White Sea on the regime functions
of mean wave heights in the small probability range (Korobov & Lavrenov,
1989). It should be noted that there is a regular semi-diurnal tide with current
velocities up to 250-270 cms- 1 . In order to do this it is divided into regions
according to the prevailing role of one of two possible current influence mechanisms on the wave generation or transformation. As the estimation shows,
the diagrams of regime functions, with currents taken into account, are displaced relative to the diagrams for calm water conditions towards larger wave
heights. The estimates of the calculated wave heights appear to increase by
14-16 per cent in sea regions with strong tides.
As far as the problem of current influence on the distribution of wave elements within a quasi-stationary range is concerned, this still remains open.
At least it is well known that currents can significantly change the distribution functions of wave heights and lengths. The proportion of wave heights
and lengths greater than the mean values is decreased according to the experimental data (Krivoshey, 1976). In addition, the variation and asymmetry
coefficients are considerably changed (Mass et al., 1988). Observations in natural conditions show that the currents significantly change the distribution
function of wave heights and periods (Matushevskiy, 1985).
An estimation of wave elements of prescribed probability is performed on
the basis of the mean wave height using a distribution function. The wave
height distribution function is known to be subordinate to the Rayleigh law
for all stages of wave development. The distribution function of wave elements
in deep water is dependent on the non-dimensional fetch (Krylov et al., 1976).
This assumption is confirmed by field and laboratory experiments.
Using these results, the distribution function for the case of the influence
of current on the wave generation was estimated by Mass et al. (1990). The
current and the fetch restriction by a coastline are taken into account using
the effective fetch length. It is assumed that the wave height distribution
function preserves its form and is determined by the effective fetch:
(5.155)
where
10 3