An experimental investigation of turbulent flow characteristics beneath a simulated ice jam
Loading...
Date
2016
Authors
Pahlavan, Hoda
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Ice jams have caused serious hazards such as floods in northern countries. Despite several studies focused on river ice jams, a lack of research has been identified in the existing literature to analyze impacts of an ice jam on turbulent flow characteristics. Thus, this research attempts to address this knowledge gap. A better comprehension of flow features beneath an ice jam will help river ice engineers to reduce economic, environmental, and ecological damages.
Technical difficulties and safety concerns limit data collection in ice jam field studies. Therefore, a physical model of a river ice jam was constructed in the Hydraulics Research & Testing Facility at the University of Manitoba. Two scenarios were proposed to simulate an ice jam. The first scenario was to use a basic model with constant upstream and downstream water depth. The second scenario was developed as an extension of the first scenario, with a modified setup to allow the upstream water depth to be greater than the downstream water depth. This was done to increase similarity with the real ice jam in nature and improve the results. For the second scenario, different roughness ratios of channel bed to ice jam were defined. Experiments were conducted to quantify the turbulent flow characteristics including streamwise velocity and streamwise turbulence intensity distribution beneath the ice jam. The flow velocities were measured at different locations beneath the ice jam using an acoustic Doppler velocimeter. The turbulence intensities and bed shear stresses were calculated using the measured velocities.
The results indicated that the flow velocity and turbulence intensity were a function of the streamwise location beneath the ice jam as well as the roughness of the bed and ice jam. Significant changes were observed in the velocity and turbulence intensity profiles where the boundaries were fully rough, which could influence an ice jam formation, sediment concentration and water quality, as well as river bed deformation. It is believed that the results from this research will improve our fundamental understanding of flow beneath an ice jam, and can be used for validation of subsequent ice jam numerical models.
Description
Keywords
Ice Jam, Flow Characteristics, Experimental Study