ABSTRACT
When flexible structures are placed in a flow, the predominance of Fluid-Structure Interaction (FSI) phenomena is observed. These structures produce important changes in the flow and energetic dissipations. Pressure loss generated is dependent on mechanical and geometric characteristics of structures and on their arrangement in the flow. The study presented is about modelling pressure loss due to the local presence of a patch of flexible structures in an experimental river flow. Experiments were carried out in the hydrodynamic open channel of the P-PRIME Institute (University of Poitiers - France). Pressure loss was evaluated by measuring water depth, upstream and downstream from the patch of structures with acoustic sensors. The studied flexible structures are vertical stems of circular cylinders with mechanical and geometrical characteristics comparable to plant structures. They are placed locally in the channel with a maximum of 4 staggered rows oriented perpendicularly to the mean flow. They are regularly placed in each row and on the entire width of the channel. 4 densities are studied with a mean flow velocity from 0.5m/s to 1.25m/s and several rows from 1 to 4. The objective of the study is to conclude on an empirical model that characterized pressure loss by connecting, Cauchy numbers, density of stems and number of rows. These results pave the way to applicative studies using flexible structures as dissipative sources for low slope channel as fishways.
