Yves Gagnon

Numerical simulation and physical analysis of high Reynolds number recirculating flows behind sudden expansions

This work presents the results of numerical simulations of unsteady recirculating flows at high Reynolds number. The two geometries investigated are a two‐dimensional channel that incorporates a sudden expansion in the form of a single backward‐facing step and a two‐dimensional channel that incorporates a sudden expansion in the form of a double symmetrical backward‐facing step. The random vortex method (RVM) is used in this study. This grid‐free Lagrangian method solves the unsteady, incompressible Navier–Stokes equations and the continuity equation, with the appropriate physical boundary conditions, using a formulation in vorticity variables. In order to show the ability of the RVM an extensive set of numerical results is presented and compared with experimental results from the literature. In particular, the dissymmetrical behavior of the flow in the double expansion channel, as observed experimentally, is simulated accurately. Frequency analyses and autocorrelation analyses show that the flows are cha...

Study of atmospheric boundary layer flows over a coastal cliff

The extent to which a wind energy site is affected by a coastal cliff is presented by studying numerically a neutral Atmospheric Boundary Layer (ABL) flow using an RNG k-ε model and different geometries. Initially, the classical flow over a forward-facing step is modelled, followed by the modelling of a neutral ABL over a rough plane in two and three dimensions with various types of ground conditions. Finally, the two and three-dimensional flows over a forward-facing step, representing a coastal cliff, in a neutral ABL were modelled and applied to the Atlantic Wind Test Site (AWTS), site composed of a wind turbine testing facility and a 13 MW wind farm, in the province of Prince Edward Island, Canada. After assessing that the model can predict classical flows and ABL with relatively good accuracy and robustness, the results show that the extent of the effect of a coastal cliff on the flow above the AWTS is limited to a distance of 5h downstream of the (height h = 10 m) cliff. Based on the sitting of the existing wind power infrastructure, it appears that the coastal cliff does not influence the power capacity of the site.

A Methodology for the Evaluation of the Economic Impacts of Wind Energy Projects

In this paper, a methodology for the evaluation of the economic impacts of wind energy projects is presented. With an application to the Canadian setting, the methodology is based on modified input-output techniques using national/provincial economic Input-Output tables and multiplier coefficients. The model makes use of a profile of investment for a generic 100 MW wind energy project based on publicly available financial data from current wind energy projects developed and operating in Canada. Subsequently, a case study of the economic impact assessment for both the construction and operations phases of a generic 100 MW wind farm project constructed and operated in the province of New Brunswick, Canada is performed. Results show that in total, including direct, indirect and induced jobs, the construction phase could create a total of 225 person-years of labour, while the operations and maintenance phase could create a total of 17 person-years of labour annually.

Fast Vortex Method for the Simulation of Flows Inside Channels With and Without Injection

A fast vortex method is presented for the simulation of fluid flows inside two-dimensional channels. The first channel studied is formed by two parallel walls simulating the entrance length of a developing flow. The second channel is similar to the first one but with an injection of a secondary fluid through a slot on one of its walls. In both cases, results are presented for flows at low Reynolds numbers and for flows at a high Reynolds number. The numerical method used is based on the Random Vortex Method and on the Vortex-In-Cell algorithm. Physical analyses of the numerical results are also presented, mostly in application to film cooling.

Development of a Wind to Power Model for Wind Farm Power Production Forecasting

The objective of this study is to develop a Wind to Power forecasting methodology where wind farm power curves are used to convert the predicted wind speeds to predicted power productions of wind farms. A methodology is proposed to develop a wind farm power curve by performing several experiments using historical wind farm power productions and wind measurements. A simple method, the Bins Method, is compared to an advanced method based on Artificial Neural Networks (ANN). It is shown that the advanced method does not have significant advantages in terms of accuracy. However, due to its flexibility on the choice of input parameters, the ANN method is best suited for studies such as the optimal selection of input parameters. For this reason, these two methods are used alternatively in this study according to the applications. The influence of different meteorological parameters on the wind farm power curve has also been investigated with the ANN method. The wind farm power curves developed in this work have been tested for the prediction of the wind power productions using forecasted wind speed data obtained from a Numerical Weather Prediction model (GEM-LAM) as input variables to the Wind to Power model. The predicted power productions compare well with those recorded at the wind farm. The proposed method is applied to a second operating wind farm to demonstrate its validity.

Vortex simulation of axisymmetrical flows in cylindrical geometries. Part II: Application to pipes incorporating an orifice plate

The Random Vortex Method extended to an axisymmetrical flow is used in the study of the flow field inside pipes incorporating an orifice plate with different contraction ratios and different inlet velocity profiles. Three test-cases, each having experimental measurements available in the literature, are studied. In particular, instantaneous and average velocity fields along with the turbulent statistics for high Reynolds number flows are computed and compared to the corresponding experimental results. These comparisons show the ability and the limitations of the method. The results of the numerical simulations are used in the physical analysis of the flow fields and thus allow for a better understanding of the dynamics of the flow in pipes incorporating an orifice plate.

On the wind resource mapping of Burkina Faso

ABSTRACT In this work, mesoscale wind resource maps, at 5-km resolution, of the country of Burkina Faso (274,200 km2) were developed using the Anemoscope and mesoscale compressible community models. Results show that the northeast region of Burkina Faso has a good wind regime at 80 m above ground level (agl), while the wind regime in other parts of the country is generally low, even at 80 m agl. In addition, the technical power potential and the potential annual energy production that can be generated from the wind in Burkina Faso are identified using analysis tools based on geographical information systems and economic constraints. Results from the technical power potential at 80 m agl show that a total of 312 MW of wind farms, generating annually a total of 741 GWh of energy, could be installed in Burkina Faso. On the other hand, a total of 4411 MW of small wind turbines (50 kW) could be installed over the territory, corresponding to an annual energy production of 7843 GWh. The Wind Atlas of Burkina Faso provides an opportunity for local stakeholders to consider wind energy for the electricity portfolio of the country.

PIV measurements around 2D and 3D building models

Particle image velocimetry (PIV) measurements for three Reynolds numbers were performed around two-dimensional and three dimensional model buildings that were placed inside an Eiffel type wind tunnel. For the 2D model, the height was half the length while for the 3D model the height equaled half the width and the length. Along with the velocity measurements, pressure measurements on the center plane of the models were also taken. Noticeable differences in the pressure coefficient distribution between the 2D and 3D models were observed. However, there are no significant Reynolds number effects in the range studied for both types of models.

Numerical simulation of the flow over a model of the cavities on a butterfly wing

The objective of this paper is to present results of numerical simulations for the flow over cavities modeling the scale structures on the upper surface of a typical butterfly wing. The numerical results, obtained using a vortex method, show that the dynamics of the flow are strongly dependent on the Reynolds number of the flow. The large coherent structures, formed in the cavity of adjoining scales, exhibit a stationary behaviour for low Reynolds number flows, while they exhibit strong dynamics and instabilities for high Reynolds number flows. The numerical results are in very good agreement with corresponding experimental results available in the literature.

Vortex simulation of axisymmetrical flows in cylindrical geometries. Part I: Numerical algorithm

The Random Vortex Method extended to an axisymmetrical flow is used in the study of the flow field inside circular geometries characterized by an axis of symmetry. The method uses a formulation in vorticity variables expressed in cylindrical coordinates with the assumption of an axisymmetrical flow. The algorithm uses a semi-Lagrangian approach for the simulation of the vortex dynamics. In this paper, the algorithm of the computational method, along with a description of the method of vorticity generation on solid walls, are presented in detail.