INVESTIGADORES
STORTI Mario Alberto
artículos
Título:
Dynamic boundary conditions in Computational Fluid Dynamics
Autor/es:
STORTI, M.A.; NIGRO, N.N.; PAZ, R.R.; DALCÍN, L.D.
Revista:
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
Editorial:
Elsevier
Referencias:
Lugar: Amsterdam, Holanda; Año: 2008 vol. 197 p. 1219 - 1232
ISSN:
0045-7825
Resumen:
The number and type of boundary conditions to be used in the numerical
modeling of fluid mechanics problems is normally chosen according to a
simplified analysis of the characteristics, and also from the
experience of the modeler. The problem is harder at inflow/outflow
boundaries which are, in most cases, artificial boundaries, so that a
bad decision about the boundary conditions to be imposed may affect the
precision and stability of the whole computation. For inviscid flows,
the analysis of the sense of propagation in the normal direction to the
boundaries gives the number of conditions to be imposed and, in
addition, the conditions that are absorbing for the waves
impinging normally to the boundary. In practice, it amounts to counting
the number of positive and negative eigenvalues of the advective flux
Jacobian projected onto the normal. The problem is even harder when the
number of incoming characteristics varies during the computation, and
the correct treatment of these cases poses both mathematical and
practical problems. One example considered here is a compressible flow
where the flow regime at a certain part of an inlet/outlet boundary can
change from subsonic to supersonic and the flow can revert. In this
work the technique for dynamically imposing the correct number of
boundary conditions along the computation, using Lagrange multipliers
and penalization, is discussed and several numerical examples are
presented.