DSMC Simulation of the Subsonic Flow Past a Vertical Plate

• Main Authors: Shin-Chieh Lin, 林士傑
• Other Authors: Jong-Shinn Wu
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/36965453204015601503

碩士 === 國立交通大學 === 機械工程系所 === 96 === The phenomena of vortex shedding associated with the subsonic external flow problems in different length scales are visible everywhere in fluid dynamics. For example, aviation of fruit flies and birds, driving car in the wind, flowing river through piers under a bridge, and the air current interaction with an island and so forth. A large number of experimental and numerical studies have been reported on the vortex-shedding flows in the continuum limit, while there have been very few studies focusing on similar flows in the rarefied gas regime. Major obstacle of the investigation in rarefied regime mostly came from the difficulties of experiments and also numerical simulations for unsteady flows in this regime. In the present paper, a general-purpose Parallel Direct Simulation Monte Carlo Code, named PDSC, is used to simulate the subsonic flow pasts a 2D vertical plate for studying the vortex-shedding phenomena. An unsteady time-averaging with temporal variable time step sampling method, called TVTS. Parametric studies, including temporal variable time step (TVTS) factor, particles per cell, number of temporal nodes, domain size and Reynolds number, are conducted to obtain the Strouhal number and aerodynamics coefficients. The results are compared to experimental data in the continuum region and simulations from the literature wherever they are available. Results of TVTS=100 and 150 has oscillation phenomenon, but results of TVTS=100 has results clear vortex shedding. Both the Strouhal number (0.174, 0.188, and 0.21) and the average drag coefficients (1.05, 1.14, 1.35, and 1.4) are increased with respect to Re=73, 126, 287 and 412 respectively, expect that the Strouhal value of Re=73 case is unavailable because the vortex is steady.