INVESTIGADORES
ELASKAR sergio Amado
artículos
Título:
Reducing the Numerical Viscosity in Non Structured Three-Dimensional Finite Volumes Computations
Autor/es:
FALCINELLI, OSCAR; ELASKAR, SERGIO; TAMAGNO, JOSÉ
Revista:
JOURNAL OF SPACECRAFT AND ROCKETS
Editorial:
American Institute of Aeronautics and Astronautics
Referencias:
Año: 2008 vol. 45 p. 406 - 409
ISSN:
0022-4650
Resumen:
When solving numerically the fluid mechanic equations using finite volume techniques, the necessity of computing convective fluxes arises. Traditional approaches for computing such fluxes give good results if the variables undergo smooth variations, however, they have serious difficulties if the solution contains discontinuities. In these cases, the numerical schemes that use second or higher order approximations develop convergence problems and the solution has oscillations next to discontinuities. On the other hand, the schemes that use first order approximations generate solutions without oscillations but, the discontinuities may poorly be resolved. To deal with this problem, flux limiter functions were built as linear combinations of first and second order approximations.1,2 In this lineal combination, if the first order approach has more weight than that of second order, the scheme becomes diffusive and reciprocally, if the second order approach has more weight the scheme becomes compressive. In robust schemes the number of limiter functions is equal to the number of equations and a spectral decomposition is used.3 For the three-dimensional Euler equations system, the spectral decomposition leads to the appearance of three lineally degenerate families of waves.4  Discontinuities associated with these waves are very difficult to resolve except for schemes that use higher compressive limiters, however, schemes with these limiters are not very robust in solving discontinuities associated with the non lineal wave families.2  In this work, a scheme is described which has the capacity to solve satisfactorily discontinuities associated with lineally degenerate wave families without losing robustness. It was implemented in a computational code that using a non-structured finite volume technique, solves the three-dimensional Euler equations. Results obtained in some applications are presented.