“…In particular, for the Stokes problem, M. Ainsworth and J. Oden [2], D. Kay and D. Silvester [23], C. Cartensen and S. A. Fuken [9] and R. Verfurth [31] introduced several error estimators and provided that they are equivalent to the energy norm of the errors. Other works for the stationary Navier-Stokes problem have been introduced in [27], [32], [22], [34], [1], [26], [3].…”