Author(s): Shawn P. Clark; Mitchel Peters; Karen Dow; Jarrod Malenchak; Devon Danielson
Linked Author(s): Shawn Clark
Keywords: No Keywords
Abstract: Unlike open channel flow or flow in channels with a complete ice cover, the flow characteristics beneath a river surface with a partial ice cover extending from each bank is not well understood. Border ice can form along the banks of a river during the winter freeze-up season, and in some cases a channel can remain partially ice-covered for a significant duration. Partial ice covers can also develop throughout the winter in some river reaches and persist for much, if not all of the winter. To better understand the effects of a partial ice cover on the flow characteristics within a river, an experimental program was developed at the Hydraulics Research& Testing Facility at the University of Manitoba. A 14 m long, 1.2 m wide rectangular channel was constructed, and a simulated ice cover was installed on each side wall using high density overlay plywood. A set of four experiments were designed to quantify the effects of channel bed and border ice roughness on the flow characteristics within a partially covered rectangular channel. Detailed velocity and turbulence intensity measurements were taken using an acoustic Doppler velocimeter beneath the ice, as well as within the open water portion of the channel. It was found that roughness had a very significant impact on flow redistribution beneath the ice cover. The flow redistribution subsequently effects the boundary shear stress on the bed and ice cover, which in turn may impact border ice growth rates and bed scour throughout the winter.