In this paper, we show the numerical and experimental results of two-dimensional fluid motions inside a rectangular container with a vertical plate subjected to a background rotation added by a rotational oscillation. In the PIV experiment we apply a new algorithm, NTSS, to the velocity calculation. In the numerical computation, the linear Ekman-pumping model was used to take the bottom friction effect into account. It was found that it showed good agreement with the experimental results at low ${epsilon}$ number.