École Nationale Supérieure de
Techniques Avancées

Abstract

The aim of the internship is to study the 2D flow around obstacles with separation and to characterize the evolution of several parameters such as drag or lift as a function of the angle between the axis of the body and the direction of the flow. The simulations are performed in 2D and are based on the Navier-Stokes equations. The code used is Freefem++ and the data are analyzed with Matlab. This internship is part of a project of the Liverpool Fluid Mechanics Laboratory which is conducting experimental tests in a wind tunnel on 3D bodies to compare our results and see if the phenomena observed in 3D are also observed in 2D. After checking that the code gives consistent results for the flow around a cylinder, we select a half-ellipse geometry to avoid boundary layer separation before the back of the obstacle, and we set the Reynolds number high enough. When analyzing the results, we observe many differences between the 2D and 3D results in parameters such as drag or recirculation length. The observed results are analyzed in order to try to give them a physical explanation. Moreover, we try to study the flow around other obstacles such as a splitterplate or a cavity. The results found confirm that the phenomena observed in 3D are therefore purely 3D and their explanation is not solved through this course.