Résumé
The numerical simulation of low Mach compressible flows around a generic airship is investigated using a Godunov-like numerical method. The hyperbolic differential problem -the three-dimensional Euler equations- is solved on unstructured meshes by a finite volume scheme based on Roe's upwind scheme [7] and Turkel's low Mach preconditioner [12, 5, 9, 10]. The effects of artificial viscosity and preconditioning on the computation of Drag and Lift coefficients are investigated. The classical Roe's scheme and its low Mach preconditioned variant are both considered using a sequence of three meshes of different fineness for solutions comparison and convergence. The numerical results show the preponderant part played by the low Mach preconditioner in terms of accuracy and robustness when very subsonic flows are considered, and the importance of using a small amount of numerical dissipation.