Simulation Of Three Dimensional Flows Past Infinite Cylindrical Bodies

Download or read book Simulation of Three-dimensional Flows Past Infinite Cylindrical Bodies written by Tanvir Akbar and published by . This book was released on 2010 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: The thesis sheds light on the onset of three-dimensionality in the wake of infinite cylindrical bodies. The first part of thesis consists in an investigation of the wake of a straight infinite circular cylinder by 3D simulations. It shows that the subcriticality of the bifurcation giving rise to the onset of three-dimensionality triggers very strong non-linear effects limiting considerably the relevance of the linear theory. The flow dynamics is shown to be chaotic and to contain very large spanwise scale that must be taken into account to reproduce reliably experimental observations. The obtained numerical results set the subcritical bi-stability interval down to the Reynolds number of 170 and show that the well-known modes A and B co-exist in all regimes since the very onset of the three-dimensionality. The method of investigation of the cylinder wake is further applied to a NACA0012 airfoil with variable angle of incidence. The onset of three-dimensionality is investigated for angles of incidence from 8 to 12 degrees. The corresponding bifurcation is supercritical. The obtained spanwise scales might be of use in designing efficient direct numerical simulations.