Performance of the Vectrino Profiler at the sediment–water interface

The Vectrino Profiler is increasingly recognized as a promising instrument for characterizing near-bed velocities and turbulence due to its high spatio-temporal resolution and velocity profiling range. However, its measurement performance in the vicinity of the bed (<10 mm) is not well documented. This study reports on the comparisons of mean velocity, turbulent kinetic energy, and power spectral density above various bed materials between the Vectrino Profiler and particle image velocimetry in a laboratory flume. Our analyses demonstrate that the bed interference adversely influences the measurements as close as 1.7–5 mm above the bed, depending on the bed material. We provide a criterion to identify the vertical extent of the interference region. Outside of the interference region, best agreement between the Vectrino Profiler and particle image velocimetry was found around the sweet-spot of the profiler where the observed differences were <6% for mean velocities and <10% for turbulent kinetic energy.

Vectrino剖面仪（Vectrino Profiler）凭借其高时空分辨率与流速剖面测量范围，正日益被视作表征近底流速与湍流的极具潜力的观测仪器。然而，其在床面附近（<10毫米）的测量性能尚未得到充分的文献记录。本研究通过实验室水槽实验，对比了不同床面材料工况下，Vectrino剖面仪与粒子图像测速法（particle image velocimetry）在床面上方区域的平均流速、湍动能及功率谱密度测量结果。分析表明，床面干扰会对床面上方1.7~5毫米范围内的测量产生不利影响，该干扰范围的具体区间取决于床面材料类型。本研究提出了一种用于确定该干扰区域垂直范围的判定准则。在干扰区域之外，当测量处于Vectrino剖面仪的最佳测量区间时，二者的测量结果吻合度最优，此时平均流速的相对差异小于6%，湍动能的相对差异小于10%。