Use of numerical simulations to investigate the performance of a virtual acoustic Doppler current profiler in characterizing flow

acoustic Doppler current profiler (ADCP);direct numerical simulation (DNS);sampling;turbulence;velocity flow fields

Boldt, Justin ; Garcia ; Marcelo H.

关键词: acoustic Doppler current profiler (ADCP);    direct numerical simulation (DNS);    sampling;    turbulence;    velocity flow fields;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/45586/Justin_Boldt.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This research investigates the spatial and temporal sampling strategies of a virtual acoustic Doppler current profiler (ADCP) in characterizing flow fields and mean velocity profiles from stationary and moving platforms. This was accomplished in part using a data set with high temporal and spatial resolution from a direct numerical simulation of turbulent open channel flow. The extent of the effect of non-homogeneous flow on the flow field produced by an ADCP is unknown. The numerical simulations presented in this research were resampled like an ADCP, processed, and then compared to the original flow field to see how well they were reconstructed.The primary research objective was to investigate the reliability of flow field visualizations generated from ADCP data. This was accomplished with two different numerical simulations. The first tested what happens when variations of a single roller eddy move through an ADCP beam field. The second tested various ADCP configurations and transect averaging. The benefit of using numerical simulations was not only the ability to have a perfect reference, but also the ability to vary the physical aspects of the flow field and the virtual instrument. Findings indicate the importance of the effect of the beam angle on the measurement technique and that the measured turbulence quantities are good estimates.This research investigated the capabilities and limitations of an ADCP in terms of what scales of coherent flow structures it can resolve. Although some of the results were intuitive, they strengthen the knowledge base already held by the river research and velocity flow mapping communities. The continued focus on using ADCPs to characterize flow will greatly advance the study of fluvial geomorphology and river morphodynamics. It is important to understand the performance of the sampling strategies of ADCPs so that they can continue to be used for measurements and research in a variety of ways with the assurance that the data are quality and representative of the actual flow field.