Research on Backflow Region Length of Sudden-Enlarge Oil Tube Flows

Jiahong Wang, Wanzheng Ai*
Institute of Navigation, University of Zhejiang Ocean, Zhoushan, 316022, China

© 2014 Wang and Ai

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Institute of Navigation, University of Zhejiang Ocean, No.1 South Road, Dinghai District, Zhoushan, 316022, P.R. China; Tel: 15257070064; E-mail:


Sudden-enlarge tube has important applications in reality lives. The backflow region length in sudden-enlarge tube flows is closely related with its energy loss. In this paper, the characteristics of backflow region length in suddenenlarge oil tube flows are researched. The results show that backflow region length decreases with the increase of the contraction ratio; when Reynolds number is more than 105, Reynolds number have little impacts on backflow region length. Empirical expression about backflow region length is also obtained by fitting curve in this paper.

Keywords: Backflow region, Contraction ratio, Reynolds number, Simulations, Transportation in tube.