Study of unstructured finite volume methods for the solution of the Euler equations
Document typeMaster thesis
Rights accessOpen Access
This work deals with the numerical solution of inviscid compressible flows by means of the Euler equations. It focuses on the description of an unstructured finite volume method for these equations and its numerical application to solve external, two-dimensional steady problems. On first place, the standard formulation of the Euler equations is presented, reviewing the most important properties that characterize their mathematical behavior. The hyperbolic nature of the system is discussed, emphasizing the fundamental importance of taking into account the propagation of information in the flow field in order to obtain physically meaningful solutions, which also leads to a description of how the boundary conditions should be treated to avoid undesirable behaviors. To complete this presentation, a dimensionless form of the equations is derived, which provides substantial advantages to the numerical solution. The attention is then focused on the unstructured finite volume formulation, which is based on a central approximation of the fluxes at the volume interfaces. According to the need of properly accounting for the propagation of characteristic variables, the requirement to add artificial dissipation terms to the central discretization is justified. Then, two classical forms of artificial dissipation are defined, namely, the first-order upwind scheme and the Jameson-Schmidt-Turkel high-order model, detailing how to adapt the formulation of the dissipation terms to an unstructured mesh. Eventually, the time integration of the spatially discretized equations is assessed. With the objective of performing a practical implementation of the theoretical concepts studied, the development of a numerical solver is presented next, briefly describing the program structure and characteristics. After that, five different test cases are solved with the purpose of validating the code, consisting on two transonic flows around a NACA0012 airfoil and three supersonic examples, respectively around a NACA0012 airfoil, a double wedge airfoil and circular cylinder. The results obtained for each case are then analyzed and compared against reference solutions, showing an overall satisfactory performance of the solver developed.
Development of an unstructured finite volume solver for the numerical solution of high-speed flows using the Euler equation set.