Numerical study on flow and heat transfer characteristics of low pressure gas in slip flow regime

• Published in: International journal of thermal sciences 2018-02, Vol.124, p.131-145
• Main Authors: Xie, Fushou, Li, Yanzhong, Wang, Xingbao, Wang, Ying, Lei, Gang, Xing, Kewei
• Format: Article
• Language: English
• Subjects: Circular cylinder; Crossing flow; Heat transfer; Low pressure gas; Numerical simulation; Slip flow regime
• ISSN: 1290-0729; 1778-4166
• DOI: 10.1016/j.ijthermalsci.2017.09.022

The flow and heat transfer characteristics in slip flow regime at low pressure state are numerically investigated by using CFD solver. The complete boundary conditions of first-order velocity slip are considered by User Defined Functions (UDFs), which include effects of thermal creep and wall curvature, as well as temperature jump. Based on the dimensionless continuity, momentum and energy equations along with these boundary conditions, the numerical simulation for flow and heat transfer behaviors over a circular cylinder is conducted in a wide range of Re = 0.001 to 20 and Kn = 0.01 to 0.1. It is found that the prediction results without considering the slip boundary conditions obviously deviate from the experimental values with the increase of Knudsen number, while the one by the developed model is in good agreement with the experimental results. Meanwhile, the variation of physical fields under different Reynolds and Knudsen numbers is discussed in detail. The empirical correlations in the slip flow regime for predicting average drag coefficient and average Nusselt number are proposed on the basis of simulation data, which makes the traditional method used for continuous flow regime be successfully applied into the prediction of flow and heat transfer performances in the slip flow regime. •Numerical simulation in the slip flow regime of low pressure gas is achieved.•The slip boundary conditions considering wall curvature are imposed into Fluent solver.•The simulation results are in good agreement with our previous experimental data.•The variation of physical fields under different Re and Kn numbers is discussed.•The empirical correlations in the slip flow regime for CD and Nu are proposed.