The characteristics of high speed, high pressure, microscale, and rotating flow fields result in very complicated flow between the dynamic and static rings of a dry gas seal. In particular, the existence of a groove, dam, and weir further contribute to the uncertainty of a microscale flow field. Classically, the flow regime of pipe flow is determined based on the critical Reynolds number (Pipe model) while the rotating flow field is sometimes determined by the flow factor (Oval model). In this study, a new method was developed that can be used for prediction of flow regime of a dry gas seal rotating flow field based on a three-dimensional velocity component (Ellipsoid model). The aim was to make the given model reflect the flow regime more realistically based on the consideration of the axial velocity component. When modeling dry gas seal rotating flow fields, we showed that compared to the one-dimensional Pipe model and the two-dimensional Oval model, the three-dimensional Ellipsoid model proposed in this paper can produce more accurate results. QIONG HU received the Ph.D. degree in mechanical engineering from Nanjing Forestry University, Jiangsu, China, in 2016. She worked as an Engineer with NGC, Jiangsu, until March 2018. She has a half-year experience of studying with the Department of Mechanical Engineering, Louisiana State University. She is currently a Lecturer and teaches several professional courses of mechanical engineering with Jiangsu Ocean University, Jiangsu. She has published 14 research articles in the journals. Her research interests include fluid sealing technology, tribology, numerical simulations, and heat transfer.