标题：Reducing Darcy coefficient by using drag reduction methods in open-channel flows: Effect on discharge capacity and potential application to mitigate river flooding impact
摘要：Drag reduction by polymer addition is a common strategy used
to minimize friction losses in pipe flows but has not been tested in river
flows. Present paper then aims at measuring backwater curves and velocity
profiles within smooth and rough bed flume configurations to assess the
capabilities of such polymer addition to decrease the water depth with
regards to the use of plain water and thus increase the channel conveyance.
The inclusion of a limited amount of polymers proves to be able to reduce
the typical Darcy-Weisbach friction coefficient with regards to plain water
by a factor 2 in smooth bed conditions and a factor 1.5 in rough bed
conditions. Moreover, the vertical profiles of streamwise velocity appear to
be hardly affected by the addition of such polymers. Whether such drag
reduction would still be effective in real watercourses remains unknown
and would now require field experiments at larger scale.
其他摘要：Drag reduction by polymer addition is a common strategy used to minimize friction losses in pipe flows but has not been tested in river flows. Present paper then aims at measuring backwater curves and velocity profiles within smooth and rough bed flume configurations to assess the capabilities of such polymer addition to decrease the water depth with regards to the use of plain water and thus increase the channel conveyance. The inclusion of a limited amount of polymers proves to be able to reduce the typical Darcy-Weisbach friction coefficient with regards to plain water by a factor 2 in smooth bed conditions and a factor 1.5 in rough bed conditions. Moreover, the vertical profiles of streamwise velocity appear to be hardly affected by the addition of such polymers. Whether such drag reduction would still be effective in real watercourses remains unknown and would now require field experiments at larger scale.
