The effect of system rotation on the development of turbulent wakes and boundary layers is of fundamental importance in the study of rotating machinery. The purpose of this Lecture Series is to understand the role of system rotation in turbulent flows from general standpoint as well as from the aspect of rotating machines. Modeling techniques will then be presented, including the state-of-the-art LES, closure modeling and transition applied to rotating machinery flows. Experimental investigations of rotating boundary layers and wakes will also be discussed to enhance the physical understanding in the context of rotating machines.