A particle-free stereo-video free-surface reconstruction method for wave-tank experiments

This paper introduces a new stereo-video-based free-surface reconstruction system developed for wave-tank experiments. The originality of the proposed approach relies on the use of short water waves and an adapted lighting system to create a fine texture suitable for the cross-correlation of the stereo image pairs. The feasibility of the approach is demonstrated experimentally in a wave flume. The accuracy of the stereo-video free-surface reconstruction method is assessed through comparisons with measurements performed with a servo-controlled wave gauge. The reconstruction of the free surface at rest and during different regular (periodic) long-crested wave experiments are considered for this purpose. The results demonstrate that, with a suitable free-surface roughness, the accuracy of the stereo-system can be similar to the accuracy of the wave gauge. The accuracy, the simplicity and the flexibility of the approach, which does not necessitate any seeding or dying of the water, nor the use of a laser light source, make it a promising measurement technique for water-wave experiments.