山区河流垂线流速分布类型的分形研究

Fractal study on types of vertical flow velocity distribution in mountain river

根据长江上游螃蟹碛至火焰碛水道实测资料,对该河段水流垂线流速分布类型进行归纳;利用分形理论研究了"3"型垂线流速分布,并探讨流量、水位和河道横纵坡降对分形维数的影响。研究结果表明:研究河段垂线流速分布可分为"3"型、"反3"型、"C"型、"反C"型、"1"型、"S"型、"7"型、"反S"型和"类指数"型,其中"3"型流速分布出现频率最高;"3"型垂线流速分布呈一阶累计和变维分形,其实质上是对数流速分布在多种因素作用下发生偏离的结果;垂线流速分布的分形维数与流量、水位和坡降成正相关,但三者对分形维数影响不大。

According to the measured data of the reach between the Pangxieqi and the Huoyanqi in the upper reaches of the Yangtze River,the distribution types of the vertical flow velocity of the river are summarized.We studied the vertical flow velocity distribution of“3”type by fractal theory.The influence of flow rate,water level and channel slope drop on the fractal dimension are discussed.The results show that:the vertical flow velocity distribution of the river segment can be divided into:“3”type,“anti-3”type,“C”type,“anti-C”type,“1”type,“S”type,“7”type,“anti-S”type and“class index”type,and the“3”type of the vertical flow velocity distribution has the highest frequency.There is a fractal phenomenon in the“3”type of the vertical flow velocity distribution and it has a first-order accumulated variable-dimensional and fractal phenomenon.It is essentially a result of the deviation of logarithmic flow velocity distribution under the action of a variety of factors.The fractal dimension of vertical flow velocity distribution is positively correlated with flow,water level and slope,but the three factors have little effect on fractal dimension.