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The extraction of energy from flowing water in rivers and tidal regions is gaining acceptance around the world as a means of generating electricity without the use of conventional hydropower dams. The purpose of this guideline is to provide a uniform methodology that will ensure consistency and accuracy in the estimation, measurement, characterisation, and analysis of the velocity/hydrokinetic resource at sites that could be suitable for the installation of an individual or array of turbines, together with defining a standardised methodology with which this resource can be described and reported.

International audience; An analysis of the vortex dynamics in the wake of three different free-stream turbine concepts is conducted to gain a better understanding of the main processes affecting the energy recovery in their wakes. The turbine technologies considered are the axial-flow turbine (AFT), the cross-flow turbine (CFT), also known as the H-Darrieus turbine, and the oscillating-foil turbine (OFT). The analysis is performed on single turbines facing a uniform oncoming flow and operating near their optimal efficiency conditions at a Reynolds number of $10^7$. Three-dimensional Delayed Detached-Eddy Simulations are carried out using a commercial finite-volume Navier-Stokes solver. It is found that the wake dynamics of the AFT is significantly affected by the triggering of an instability while that of the CFT and the OFT are mainly governed by the mean flow field stemming from the tip vortices’ induction.

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Dumas Guy. La politique linguistique québécoise. In: Revue Québécoise de droit international, volume 12-1, 1999. Séminaire international de Montréal sur l'éducation interculturelle et multiculturelle. Actes, sous la direction de François Crépeau, Stéphanie Fournier et Lison Néel. pp. 65-78.

Incompressible, viscous flows in the spherical gap between a rotating inner-sphere and a stationary outer-shell, Spherical Couette Flows (SCF), are studied via direct numerical simulations. The investigation covers both "small-gap" and "large-gap" geometries, and is concerned primarily with the first occurrence of transition in those flows. Strong emphasis is put on the physical understanding of the basic flows and their transition mechanisms. An alias-free spectral method, based on divergence-free vector expansions for the 3-D velocity field in spherical coordinates, is developed. The vector expansions are constructed with Chebyshev polynomials in the radial direction and Vector Spherical Harmonics for the two angular directions. Accuracy and spectral convergence of the resulting initial-value code are thoroughly tested. Three-dimensional transitional flows in both narrow-gaps and large-gaps as well as axisymmetric transitions in moderate-gaps are simulated. For small-gap SCF's, this study shows that the formation of Taylor-vortices at transition is a deterministic process and not the result of the instability of initial perturbations. The formation process involves the sub-critical appearance of a saddle-stagnation point within the meridional circulation cell in each hemisphere. A minimum length-scale ratio is shown necessary, and for a given inner-sphere radius, this leads to a theoretical prediction of the largest gap-width in which Taylor-vortices may form. This investigation confirms that the first transition in large-gap SCF's is caused by a 3-D instability of a linear nature. It is found that the process is characterized by very small growth-rates of the disturbance and by the absence of a "jump" in the friction torque. The supercritical flow is a complex-structured, laminar, time-periodic flow that exhibits traveling azimuthal-waves. The physical mechanism responsible for the large-gap transition is shown to be related to a shear instability of the "radial-azimuthal jet" that develops at the equator of the basic flow. A physical model is proposed in which that jet is viewed as a sequence of adjacent "fan-spreading quasi-2-D plane jets". Predictions from the model are presented and verified from the computed unstable disturbance field. Extension of the model to the transition toward waviness in the Taylor-Couette flow, the Gortler-vortex flow and the Dean-vortex flow is proposed.