Solving stiff chemistry problems with FIDAP
Stiff means high fluid-phase on surface reaction rate relative to transport rate. A method for implementing surface-only species in FIDAP has been demonstrated. The method requires no modifications to the FIDAP source code or custom subroutines but instead relies on a novel application of FIDAP commands. Although the surface species are formally treated as also existing in the fluid phase, concentrations of these species are mathematical unknowns only on the reactive surfaces, rather than throughout the fluid phase, which keeps the problem size manageable. To take full advantage of this capability, however, it is necessary to employ the full Jacobian for the chemical-reaction source terms in the solution algorithm. An implementation of the full Jacobian of chemical-reaction source terms was demonstrated. This approach allows solution of extremely stiff chemically reacting problems. However, the resultant equations are inherently cross coupled: variations of all species simultaneously affect the chemical-reaction source term portions of all the equations. This precludes solution of the system by a straightforward application of a segregated approach which may be the only practical way at present to solve large three-dimensional problems. To circumvent this difficulty, an approach was demonstrated that maintains an approximate form of the cross-species chemical coupling but permits application of a segregated approach. For problems in which convection dominates diffusion, upwinding must be employed to maintain stability.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 56678
- Report Number(s):
- SAND-95-0197C; CONF-9504145-1; ON: DE95011053
- Resource Relation:
- Conference: Fluid dynamics international (FIDAP) users conference, Chicago, IL (United States), 30 Apr - 2 May 1995; Other Information: PBD: [1995]
- Country of Publication:
- United States
- Language:
- English
Similar Records
Semi-implicit and fully implicit shock-capturing methods for hyperbolic conservation laws with stiff source terms
Development, Implementation, and Verification of Partially-Ionized Collisional Multifluid Plasma Models in Drekar