Efficient and accurate estimation of water surface velocity in STIV
Efficient and accurate estimation of water surface velocity in STIV
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DOI：
10.1007/s10652-018-9651-3
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发表时间：
2019-10-01
影响因子：
2.2
通讯作者：
Tateguchi, S.
中科院分区：
文献类型：
--
作者：
Fujita, I;Notoya, Y.;Tateguchi, S.
在浅水流条件下，湍流效应在水面上表现为由大量波动波纹组成的不规则表面形状。这种波动的强度随着弗劳德数和雷诺数的增加而增加，正如在洪水泛滥的河水流量中可以观察到的那样。在这种流动条件下，表面不规则性被视为随流动移动的表面特征或纹理。尽管在地物的可追溯性方面存在一些讨论，但从实际的角度来看，地物的平流速度与地表速度非常吻合。基于表面特征可追溯性的假设，基于图像的技术在过去几十年中得到了发展。时空图像测速（STIV）是 Fujita 等人开发的技术之一。 （Int J River Basin Man 5(2):105-114, 2007），在不播种流量的情况下成功测量河流表面速度分布。然而，在从 STIV 中使用的时空图像 (STI) 确定准确的表面速度方面仍然存在一些改进的空间。为此，开发了一种新技术，该技术利用 STI 中图像强度的二维自相关函数以及 STI 的质量指数。使用合成图像及其在融雪洪水测量中的应用验证了新技术的性能。
In shallow flow conditions, turbulence effects appear on a water surface as a form of irregularity of surface shape composed of a large number of fluctuating ripples. The intensity of such a fluctuation increases with the Froude number and also with the Reynolds number as can be observed in flooding river flow. In such a flow condition, surface irregularities are viewed as surface features or textures moving with the flow. Although there has been a discussion in terms of the traceability of surface features, the advection speed of surface features agrees well with the surface velocity from a practical point of view. Based on the assumption about the traceability of surface features, image-based techniques have been developed in the past decades. The space-time image velocimetry (STIV) is one of those techniques developed by Fujita et al. (Int J River Basin Man 5(2):105-114, 2007), with success of measuring river surface velocity distributions without seeding the flow. However, there is still some room for improvement in determining accurate surface velocity from a space-time image (STI) used in STIV. For that purpose, a novel technique was developed that utilizes the two dimensional auto-correlation function of the image intensity in an STI together with quality indices of STI. The performance of the new technique was verified using synthetic images as well as its application to the measurement of snowmelt flood.