This paper analyzes triangular finite elements for the preconditioning of Chebyshev collocation solutions of elliptic boundary value problems. Results are given for scalar model problems and for both Stokes and Navier-Stokes equations.
Deville, MO., Mund, EH., & Vankemenade, V. (1994). Preconditioned Chebyshev Collocation Methods and Triangular Finite-elements. Computer Methods in Applied Mechanics and Engineering, 116(1-4), 193-200. https://doi.org/10.1016/S0045-7825(94)80023-5 (Original work published 1994)