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Finite element method, Vortex-motion, Boundary value problems, Polynomials


We introduce a method that gives exactly incompressible velocity approximations to Stokes ow in three space dimensions. The method is designed by extending the ideas in Part I ( of this series, where the Stokes system in two space dimensions was considered. Thus we hybridize a vorticity-velocity formulation to obtain a new mixed method coupling approximations of tangential velocity and pressure on mesh faces. Once this relatively small tangential velocity-pressure system is solved, it is possible to recover a globally divergence-free numerical approximation of the fluid velocity, an approximation of the vorticity whose tangential component is continuous across interelement boundaries, and a discontinuous numerical approximation of the pressure. The main difference between our method here and that of the two-dimensional case treated in Part I is in the use of Nédélec elements, which necessitates development of new hybridization techniques. We also generalize the method to allow for varying polynomial degrees on different mesh elements and to incorporate certain nonstandard but physically relevant boundary conditions


This is the author’s version of a work that was accepted for publication in SIAM Journal on Numerical Analysis. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. A definitive version was subsequently published in SIAM Journal on Numerical Analysis, 43(4), 1651–1672, and can be found online at:



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