Optical methods in the laboratory: An application to density currents over bedforms

Experimental results on density currents flowing over bedforms are presented, with the dual objectives of describing our findings for these flows as well as highlighting the strengths and challenges of the optical techniques used. Particle Image and Particle Tracking Velocimetry (PIV; PTV) provide the spatial and temporal resolution to examine the velocity field; Laser Induced Fluorescence (PLIF) does the same for the density field. Simultaneous measurements of these techniques - that resulted in the development of novel measuring and processing methodology - are extensively used to characterize the flow. Evidence regarding the effect of bed morphology on the mixing and entrainment capacity of the flow, is presented for an experiment designed with this objective, corroborating field results that indicate such effect.