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Preprint 2018-08

Gabriel N. Gatica, Bryan Gomez-Vargas, Ricardo Ruiz-Baier:

Formulation and analysis of fully-mixed methods for stress-assisted diffusion problems

Abstract:

This paper is devoted to the mathematical and numerical analysis of a mixed-mixed PDE system describing the stress-assisted diffusion of a solute into an elastic material. The equations of elastostatics are written in mixed form using stress, rotation and displacements, whereas the diffusion equation is also set in a mixed three-field form, solving for the solute concentration, for its gradient, and for the diffusive flux. This setting simplifies the treatment of the nonlinearity in the stress-assisted diffusion term. The analysis of existence and uniqueness of weak solutions to the coupled problem follows as combination of Schauder and Banach fixed-point theorems together with the Babuska-Brezzi and Lax-Milgram theories. Concerning numerical discretization, we propose two families of finite element methods, based on either PEERS or Arnold-Falk-Winther elements for elasticity, and a Raviart-Thomas and piecewise polynomial triplet approximating the mixed diffusion equation. We prove the well-posedness of the discrete problems, and derive optimal error bounds using a Strang inequality. We further confirm the accuracy and performance of our methods through computational tests.

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This preprint gave rise to the following definitive publication(s):

Gabriel N. GATICA, Bryan GOMEZ-VARGAS, Ricardo RUIZ-BAIER: Formulation and analysis of fully-mixed methods for stress-assisted diffusion problems. Computers & Mathematics with Applications, vol. 77, 5, pp. 1312-1330, (2019).

 

 

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