COMPUTATIONAL VISION SYSTEM FOR TURBULENCE MEASUREMENT AND CORRELATION WITH THE PHENOMENUM OF REAERATION

Resumo

Bodies of water receiving wastewater have their dissolved oxygen decreased. The recovery of oxygen concentration occurs, mainly, through the mass transfer across the air-water interface and the process is increased by the surface turbulence. The measurement of the surface turbulence level is important for the determination of the natural reaeration capacity of these  bodies of water. The method developed in this work consists on acquiring and computational processing the digital images of incidence and reflection of a laser beam on the surface flow. By using special algorithms as perspective correction, image threshold, determination of point of incidence and reflection and calculation of coordinates are obtained geometric data of the surface flow, by which the average vertical velocities and the amplified surface can be determined. These parameters are directly related with the turbulent intensity of the surface flow. With a Difference Finite Method the surface flow is simulated, reproducing important data of deformation of the surface. Through a graphic model these data are related to the reaeration coefficient K₂ for estimation of the water body's natural depuration.