A non-invasive acoustical method to measure the mean roughness height of the free surface of a turbulent shallow water flow.
A non-invasive acoustical method to measure the mean roughness height of the free surface of a turbulent shallow water flow.
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DOI：
10.1063/1.4901932
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发表时间：
2014-11
期刊：
影响因子：
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通讯作者：
A. Krynkin;K. Horoshenkov;Andrew Nichols;Simon Tait
中科院分区：
文献类型：
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作者：
A. Krynkin;K. Horoshenkov;Andrew Nichols;Simon Tait
本文利用气载声场在水槽中被动态粗糙自由流面散射的指向性，确定了紊流水深均匀的六种水力条件下的平均粗糙度。采用非线性曲线拟合的方法，使预测的指向性与指向性数据之间的误差最小。数据拟合算法是基于散射声压作为角度的函数的平均解，该平均解是通过基尔霍夫积分及其近似导出的。该解决方案考虑了声源的方向性。对于所采用的源和接收器的几何形状和声学频率，它示出的贡献，从固定相位点（粗糙表面上的单一镜面反射点）产生类似的结果，可以通过完整的基尔霍夫积分获得。反演的平均粗糙度高度的准确性与用传导波探头阵列实现的准确性相当。该方法能够非侵入性地估计流动雷诺数和均匀流动深度。
In this paper, the directivity of the airborne sound field scattered by a dynamically rough free flow surface in a flume is used to determine the mean roughness height for six hydraulic conditions in which the uniform depth of the turbulent flow. The nonlinear curve fitting method is used to minimize the error between the predicted directivity and directivity data. The data fitting algorithm is based on the averaged solution for the scattered sound pressure as a function of angle which is derived through the Kirchhoff integral and its approximations. This solution takes into account the directivity of the acoustic source. For the adopted source and receiver geometry and acoustic frequency it is shown that the contribution from the stationary phase point (single specular point on the rough surface) yields similar results to those which can be obtained through the full Kirchhoff's integral. The accuracy in the inverted mean roughness height is comparable to that achieved with an array of conductive wave probes. This method enables non-invasive estimation of the flow Reynolds number and uniform flow depth.