Gérard Pineau

Modification of vertical slot fishway flow with a supplementary cylinder

ABSTRACT The paper reports on the experimental results of a vertical slot fishway (VSF) study. Particle image velocimetry and Acoustic Doppler Velocimetry were used to estimate the effects of a supplementary cylinder, appropriately positioned inside existing VSFs, on the hydraulic parameters and the instantaneous flow patterns. Special attention was paid to the analysis of the spatial flow distribution and to the instantaneous flow dynamics initiated by the addition of a cylinder. Modifications of velocity amplitudes, flow fluctuations and vorticity values were quantified for two dimensions of VSF. The contribution of a supplementary cylinder has been quantified in order to “smooth” the effects of turbulence and to facilitate the passage of the largest number of fish irrespective of their size or swimming capacity. The results provided insights on the control of the fishway turbulence, which might help engineers to develop effective systems for the passage of fish with low swimming capabilities.

Navier-stokes analysis of a regular two-dimensional roughness pattern under turbulent flow regime

The present work deals with the flow characteristics induced by a two-dimensional textured surface. The texture consists of identical and equally spaced rectangles with characteristic lengths at least one order of magnitude larger than the clearance of the thin film. Periodic boundary conditions enable the analysis of a single groove and the complete Navier-Stokes analysis is carried on for turbulent flow Reynolds numbers. The analysis is performed for shear driven flows (Couette), pressure driven flows (Poiseuille), and combined Couette-Poiseuille flows. First, the presence of inertial forces generated by the groove is emphasized by the momentum balance performed for the computational cell. The peculiar effect of the groove is also shown by the rotor and the stator shear stresses variations. Finally, it is shown that despite the presence of fluid inertia forces, cell-averaged rotor, and stator shear stresses obtained for pure Couette or Poiseuille flows can be added or subtracted to obtain with good accuracy the characteristics of combined shear and pressure driven flows.

Navier-Stokes Analysis of Two-Dimensional Roughness Pattern Under Turbulent Flow Regime

The present work deals with the flow characteristics induced by a two-dimensional roughness pattern. The roughness pattern consists of identical and equally spaced rectangles with characteristic lengths at least one order of magnitude larger than the clearance of the thin film. Periodic boundary conditions enable the analysis of a single groove and the complete Navier-Stokes analysis is carried on for turbulent Reynolds numbers. The analysis is performed for shear driven flows (Couette), pressure driven flows (Poiseuille) and combined Couette-Poiseuille flows. First, the presence of inertial forces generated by the groove is underlined by the momentum balance performed for the computational cell. The peculiar effect of the groove is also depicted by the rotor and the stator shear stresses variations. Finally, it is shown that despite the presence of inertial forces, cell-averaged rotor and stator shear stresses obtained for pure Couette or Poiseuille flows can be added or subtracted for approximately obtaining the characteristics of combined shear and pressure driven flows.Copyright