Experimental setup for measuring roll waves on laminar open channel flows

• We detail an apparatus for roll waves simulation of viscous laminar flows.
• Light absorption technique is tested on free surface of open channel flows.
• Experimental set-up common problems are identified, facilitating reproduction.
• Roll waves measured data are available.

Experimental studies on open channel flows are explored mostly because of their importance in validating analytical and numerical models. Although steady flows are usually measured and explored, difficulties arise in the precise execution of this task when the free surface becomes oscillatory. This paper presents a methodology for measuring a particular non-stationary phenomenon that occurs under specific conditions, namely, roll waves. Limited data exists in literature on roll waves. The objective of this work is to contribute to this database and to describe a useful experimental method for measuring roll waves. Based on some well-known literature experiments, an experimental setup was designed to achieve the free surface flow of a viscous fluid in a steady and uniform configuration. The flow was set to generate roll waves and controlled disturbances were applied at the inlet to develop roll waves. These waves were then measured using a photometric device based on a light absorption technique. The wave profiles for different flow configurations are presented. Experimental results were compared with numerical simulations to assess the validity of the measurements taken.