Recovering the Free-Surface Dynamics of Shallow Turbulent Flows Using Digital Image Correlation (DIC)

Numerous studies on free-surface behaviour of turbulent flows have described it as a complex phenomenon composed of different moving features. No agreement exists as to which water surface features are expected for specific flow conditions in a channel with a rough bed. There is practical difficulty in capturing the dynamic nature of the surface with sufficient accuracy and resolution. This paper describes a series of experiments for a range of conditions over two bed topographies, in which Digital Image Correlation (DIC) was used to capture surface elevation data. Frequency–wavenumber analysis highlighted a range of disturbances assumed to be created by features of the turbulent flow. Surface wave patterns were observed to change with flow condition and indicated sensitivity to the bed arrangement. This indicated that DIC can be an appropriate method in studies that wish to examine the mechanics of surface behaviour in open channel turbulent flows.