  A posteriori error analysis is a technique to quantify the error in
particular simulations of a numerical approximation method. In this article, we
use such an approach to analyze how various error components propagate in
certain moving boundary problems. We study quasi-steady state simulations where
slowly moving boundaries remain in mechanical equilibrium with a surrounding
fluid. Such problems can be numerically approximated with the Method of
Regularized Stokelets(MRS), a popular method used for studying viscous
fluid-structure interactions, especially in biological applications. Our
approach to monitoring the regularization error of the MRS is novel, along with
the derivation of linearized adjoint equations to the governing equations of
the MRS with a elastic elements. Our main numerical results provide a clear
illustration of how the error evolves over time in several MRS simulations.
