Title: On Error Estimates of the Penalty Method
       for Unsteady Navier-Stokes Equations

Author: Jie Shen

Status: SIAM J. Numer. Anal. 32, 386-403, 1995

Abstract:

The penalty method has been widely used for numerical computations of
the unsteady Navier-Stokes equations. However the  best error
estimates available, to the author's knowledge, were not optimal, and
could lead to an improper choice of the penalty coefficient $\ep$ for time
discretizations of the penalized system. We shall derive optimal error
estimates for the penalized system and its time discretizations for
the unsteady Navier-Stokes equations.