Analysis And Study Of Wind Wave Growth Relations

It is traditionally assumed that the relationship between wave steepness and wave age is independent of the wind wave growth state. And some authors proposed that (while D is a constant ascertained by experience). On the basis of the proposed relations between wave steepness and wave age this paper assumes that the relationship between wave steepness and wave age is restricted by the wind wave growth state. Therefore on the basis of the relations proposed by HOU Yi-jun and WEN Sheng-chang, we propose while increases with dimensionless fetch , which describes a continuous state. So the new relation between wave steepness and wave age is established. Comparisons of the result of present paper with the relations already proposed and the observation data show that:The result of the model proposed in present paper accords well with the fact. It's superior to the other existing models. The formula (2.2.4)proposed in present paper accords much better with the observations, especially at small fetches. Due to the restriction of the observation data, the data at small fetches is correspondingly rare. But the ten groups data, which we choose are representative enough to reflect the predominance of the result of present paper. In present paper we also choose three groups of laboratory measurements, which the dimensionless fetch are small. From Fig.4,Fig.5 and the numbers in Table 2 it canbe seen that with the verifying examples the results of the model proposed in present paper accords well with the fact. It's superior to the other existing models. So it's reasonable that we believe that the relationship changes with the varying of dimensionless fetch. This is a sound improvement for traditional results.Then we enter on the variety of wind wave energy. Combining the relationship between wave steepness and wave age with the significant wave energy balance equation for wind wave, a new wind wave growth relation is presented. Comparisons with the other existing wind wave growth relations show that:In present paper, the increasing velocity of wave age at small fetches is quicker than the other models while the former is slower than the later at large fetches. For wave height and wave period, the start point of wind wave growth is lies in the middle of the other growth relations. At small fetches the increasing velocity is comparatively quicker and larger than the other models while at large fetches the increasing velocity obviously reduces and is less than the others. As a whole the result of present paper is close to the most representative and authoritative wind wave growth relations. However the result in present paper can clearly reflect the whole course of the growth of wind wave.The study results also indicate that wind wave grows quickly in the beginning, but with the increase of fetch wind wave tends to be saturated to the wind wave growth relations in form of power function. This is consistent with the physical concept Then basing on the relation between dimensionless fetch and dimensionless wind duration proposed by Wen, we get the relations of wave characteristic parameters (as wave age,dimensionless wave height and dimensionless period) changing with the dimensionless duration...