486 Progress in Computational Fluid Dynamics, Vol. 8, Nos. 7/8, 2008 Copyright © 2008 Inderscience Enterprises Ltd. Numerical predictions of a flow field in a hydrodynamic journal bearing with herringbone microgrooves Jr-Ming Miao Department of Mechatronic, Energy and Aerospace Engineering, Chung Cheng Institute of Technology, National Defense University, Taoyuan, Taiwan, ROC Fax: 886-3-3895924 E-mail: jmmiao@ndu.edu.tw Bao-How Chang and Ping-Hei Chen* Department of Mechanical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan Fax: 886-2-23631755 E-mail: paul_chang@avc.com.tw E-mail: phchen@ntu.edu.tw *Corresponding author Abstract: This study presents numerical predictions of the loading and flow characteristics of the two-phase lubricant flow of a Hydrodynamic Journal (HJ) bearing with herringbone microgrooves on the sleeve. This study employs a computational fluid dynamics technique to solve three-dimensional laminar Reynolds-averaged Navier–Stokes equations with a full cavitation model and obtain characteristics of a two-phase lubricant flow in a microchannel between the shaft and the sleeve. The effect of herringbone groove depth on the lubricant pressure distribution is also examined. Numerical results show the lubricant flow with different eccentricity ratio (e) values and with different herringbone geometries at different rotational speeds (ω). Keywords: hydrodynamic journal bearing; Navier-Stokes equation; cavitation. Reference to this paper should be made as follows: Miao, J-M., Chang, B-H. and Chen, P-H. (2008) ‘Numerical predictions of a flow field in a hydrodynamic journal bearing with herringbone microgrooves’, Progress in Computational Fluid Dynamics, Vol. 8, Nos. 7/8, pp.486–495. Biographical notes: Jr-Ming Miao received his Bachelor Degree from Chung Cheng Institute of Technology in 1989 and PhD Degree from National Taiwan University in 1997. Afterwards, he joined the Department of Mechanical Engineering of Chung Cheng Institute of Technology as an Associate Professor. He was promoted to a Full Professor in 2004. His research areas include CFD application on industry, micro-fluidics, PEMFC, MAV, low Reynolds number aerodynamics of flapping wing, and fluid-thermal process in cooling devices for electronic equipments. Bor-Haw Chang received his Master Degree in Aeronautics and Astronautics Engineering from the National Cheng Kung University, Tainan, Taiwan, in 1996. He has been serving as a Director of Telecom and Server Fan Division since he has joined Asia Vital Components CO., LTD., Hsin-Chuang, Taipei, Taiwan, in 2002. He is currently pursuing the PhD Degree at National Taiwan University. His current research interests include the fluid dynamic bearing design applied in cooling fan application and cooling fan design in electronic equipments. Ping-Hei Chen received his Bachelor Degree from National Taiwan University in 1980 and PhD Degree from University of Minnesota in 1988. Afterwards, he joined the Department of Mechanical Engineering of National Taiwan University as an Associate Professor. He was promoted to Full Professor in 1996. He had served as the Chairman of the Department of Mechanical Engineering of National Taiwan University from 1998 to 2001. His research areas include micro-thermal-fluid systems, Lab-on-a-chip for DNA detections, Nanofluid, MEMS fabrication technology, and cooling devices for electronic equipments. He also serves as the Program Director of Thermal, Fluid, and Energy Division, Department of Applied Science and Engineering, National Science Council in Taiwan.