Multi-channel laser doppler velocimetry (LDV) and digital image processing (DIP) in fluvial hydromechanics

Recent efforts in fluvial hydromechanics aim at the capability of reliably predicting fluvial flow, turbulence and mass transport by means of multi-dimensional hydrodynamic numerical models. For this purpose, most detailed and highly accurate experimental data are needed in order to calibrate and verify the simulation tools. An optimum, but so far non-existing measurement technique would provide the complete state-space representation of the investigated water body at a high spatial and temporal resolution. While this is far from being available, already well established optical methods, such as Laser Doppler Velocimetry (LDV) and Digital Image Processing (DIP), seem to bear the potential for coming close to the optimum if applied in effective combination. Within this paper, several corresponding applications of LDV and DIP to the investigation of compound open-channel flow are described and discussed regarding their characteristic results, advantages and disadvantages as well as possible future improvements.