Speaker: Filippo Sacco - POLIMI

Venue: lecture room 134

Title: 3D Adaptive Boundary Element Method for the Simulation of Potential Flow Past Lifting Aerodynamic Bodies

Abstract: Nowadays computational fluid dynamics has reached a central role in the engineering design of several industrial artifacts. This is particularly true for example in the aeronautic and naval engineering field. There are, however, some complications arising from the complexity of the problem to be solved, as the governing equations of the physical model, namely the Navier-Stokes equations, are computationally expensive to solve. One way to avoid this obstacle is provided by simplified flow models. A classical simplified model is based on the potential flow theory, in which an elliptic Laplace equation for the flow potential is derived from the Navier-Stokes equations under suitable simplifying assumptions. The computational complexity is reduced, whereas the capability of the model to describe the underlying physical phenomenon in relevant operating conditions is surprisingly not significantly reduced. In this seminar, we present and discuss a Boundary Element Method (BEM) to solve 2D and 3D potential flow equations around lifting bodies (airfoils and wings), analyzing different geometrical configurations. This method's main advantage is that it decreases the dimensionality of the problem, which leads to a sensible reduction of the degrees of freedom of the resulting discretized linear system. The Boundary Element Method approach also yields a natural treatment of problems in infinitely large domains. However, it works only for small angles of attack, for which the potential flow assumption is adequate. The numerical model developed in this thesis is a modification of the program π-BEM developed by Nicola Giuliani. The existing solver was able to deal with a potential flow for non-lifting bodies in two and three dimensions. We extended it in order to treat the simulation of lifting bodies in two and three-dimensional cases. A suitable iterative procedure to treat the resulting nonlinear problem which describes the flow potential on the body and its vortical wake has been introduced and will be presented in the seminar. The results will be compared to experimental data and to the results of similar models.