A priori and a posteriori error analyses of a velocity-pseudostress formulation for a class of quasi-Newtonian Stokes flows

Gabriel N. Gatica, Antonio Márquez, Manuel A. Sánchez

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


In this paper we introduce and analyze new mixed finite element schemes for a class of nonlinear Stokes models arising in quasi-Newtonian fluids. The methods are based on a non-standard mixed approach in which the velocity, the pressure, and the pseudostress are the original unknowns. However, we use the incompressibility condition to eliminate the pressure, and set the velocity gradient as an auxiliary unknown, which yields a twofold saddle point operator equation as the resulting dual-mixed variational formulation. In addition, a suitable augmented version of the latter showing a single saddle point structure is also considered. We apply known results from nonlinear functional analysis to prove that the corresponding continuous and discrete schemes are well-posed. In particular, we show that Raviart-Thomas elements of order k≥ 0 for the pseudostress, and piecewise polynomials of degree k for the velocity and its gradient, ensure the well-posedness of the associated Galerkin schemes. Moreover, we prove that any finite element subspace of the square integrable tensors can be employed to approximate the velocity gradient in the case of the augmented formulation. Then, we derive a reliable and efficient residual-based a posteriori error estimator for each scheme. Finally, we provide several numerical results illustrating the good performance of the resulting mixed finite element methods, confirming the theoretical properties of the estimator, and showing the behaviour of the associated adaptive algorithms.

Original languageEnglish (US)
Pages (from-to)1619-1636
Number of pages18
JournalComputer Methods in Applied Mechanics and Engineering
Issue number17-20
StatePublished - Apr 1 2011

Bibliographical note

Funding Information:
This research was partially supported by FONDAP and BASAL projects CMM, Universidad de Chile, and by Centro de Investigación en Ingenierı´a Matemática (CI 2 MA), Universidad de Concepción.

Copyright 2011 Elsevier B.V., All rights reserved.


  • A posteriori error estimator
  • Mixed finite element method
  • Nonlinear Stokes model
  • Twofold saddle point equation


Dive into the research topics of 'A priori and a posteriori error analyses of a velocity-pseudostress formulation for a class of quasi-Newtonian Stokes flows'. Together they form a unique fingerprint.

Cite this