A numerically stable method for integration of the multicomponent species diffusion equations

A diagonally implicit method is shown to be an effective method for integra ting the multicomponent species conservation equations. The constitutive eq uation for multicomponent diffusion is recast into a form analogous to that for binary diffusion. except that the diffusion coefficient is replaced wi th a matrix of effective multicomponent diffusion coefficients. The resulti ng matrix has properties that allow the diagonal terms to be integrated imp licitly and the off-diagonal terms to be integrated explicitly. Numerical e xperiments show the integration procedure is stable for time steps much lar ger than the diffusion equation time step condition. (C) 2001 Elsevier Scie nce.