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Numerical solution of nonlinear equations in chemical speciation calculations. (English) Zbl 0964.76074

Summary: Speciation calculations involve the computation of concentration of each individual chemical species in a multicomponent-multiphase chemical system. The numerical problem is to solve a system of coupled linear and nonlinear equations subject to the constraint that all unknowns are positive. Here we evaluate performance and accuracy of a series of nonlinear equation solvers: a quasi-Newton method with the global step determined by different line search and trust region algorithms, the conjugate gradient method with the global step determined by line search, and the solvers in the codes TENSOLVE, CONMIN and LBFGS.

MSC:

76M99 Basic methods in fluid mechanics
76V05 Reaction effects in flows
80A32 Chemically reacting flows
65K10 Numerical optimization and variational techniques

Software:

CONMIN; TENSOLVE; L-BFGS
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