Idealized River (IMAGE) University of Pennsylvania Caption Researchers from the University of Pennsylvania spent two years constructing an 'idealized river,' a doughnut-shaped apparatus the size of a large fish tank. Within the 'river' a rotating lid drives the flow of liquid over a bed of spherical acrylic particles. By adding a fluorescent dye to the fluid and shining a laser through the apparatus, the team was able to produce images of the internal 'river bed' structure and precisely track the motion of individual particles over the course of days. Credit University of Pennsylvania Usage Restrictions In context of reporting License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.