In the present study, to investigate the characteristics of subsonic rarefied gas flows efficiently, the information preservation(IP) method was applied to the direct simulation Monte-Carlo(DSMC) method to reduce statistical scatters from the DSMC method for low speed rarefied gas flows. To find the...
In the present study, to investigate the characteristics of subsonic rarefied gas flows efficiently, the information preservation(IP) method was applied to the direct simulation Monte-Carlo(DSMC) method to reduce statistical scatters from the DSMC method for low speed rarefied gas flows. To find the effects of the IP method, the results of the IP method were compared to the results of the DSMC method for the same numbers of sampling. Before the comparison, it was necessary to verify the DSMC solver. The verification of the solver was conducted by simulations of the micro-channel flows by comparing to the other researchers' DSMC results. The velocity profiles at the 2/3 section of the channel agreed well with the other researchers' results. In addition, the normalized slip velocity distributions on the wall and the pressure distributions along the centerline also agreed well with the other researchers' results. After the DSMC solvers were verified, two types of Couette flows were considered. One is the flows that have temperature differences between two plates, and the other is the flows that have moving plates. For the first Couette flows, the temperature of 373K was used for the upper plate, and of 173K for lower plate. For the second Couette flows, the upper plate is moving at 300m/s, and the temperature of 273K was used for both two plates. All simulations of Couette flows were conducted from near-continuum to free-molecular regimes. From both Couette flow simulations, it was found that the temperature jump and the velocity slip occurred on the plate surface. In addition, it was also shown that the temperature and the velocity differences between the plate and the gas became larger as the flow fields became more rarefied. Lastly, flow simulations around a NACA0012 airfoil were conducted to identify the effects of the IP method. The freestream Mach number of 0.8 was used, and the Knudsen number of 0.014 was considered. It was observed that more clear contours were obtained from the IP method than the DSMC method, since the statistical scatter error was reduced by the IP method. In addition, it was found that the velocity slip on the airfoil surface occurred due to the effects of the rarefied atmospheric environment.
In the present study, to investigate the characteristics of subsonic rarefied gas flows efficiently, the information preservation(IP) method was applied to the direct simulation Monte-Carlo(DSMC) method to reduce statistical scatters from the DSMC method for low speed rarefied gas flows. To find the effects of the IP method, the results of the IP method were compared to the results of the DSMC method for the same numbers of sampling. Before the comparison, it was necessary to verify the DSMC solver. The verification of the solver was conducted by simulations of the micro-channel flows by comparing to the other researchers' DSMC results. The velocity profiles at the 2/3 section of the channel agreed well with the other researchers' results. In addition, the normalized slip velocity distributions on the wall and the pressure distributions along the centerline also agreed well with the other researchers' results. After the DSMC solvers were verified, two types of Couette flows were considered. One is the flows that have temperature differences between two plates, and the other is the flows that have moving plates. For the first Couette flows, the temperature of 373K was used for the upper plate, and of 173K for lower plate. For the second Couette flows, the upper plate is moving at 300m/s, and the temperature of 273K was used for both two plates. All simulations of Couette flows were conducted from near-continuum to free-molecular regimes. From both Couette flow simulations, it was found that the temperature jump and the velocity slip occurred on the plate surface. In addition, it was also shown that the temperature and the velocity differences between the plate and the gas became larger as the flow fields became more rarefied. Lastly, flow simulations around a NACA0012 airfoil were conducted to identify the effects of the IP method. The freestream Mach number of 0.8 was used, and the Knudsen number of 0.014 was considered. It was observed that more clear contours were obtained from the IP method than the DSMC method, since the statistical scatter error was reduced by the IP method. In addition, it was found that the velocity slip on the airfoil surface occurred due to the effects of the rarefied atmospheric environment.
1994, Bird, G.A., Molecular Gas Dynamics and the Direct Simulation of Gas Flows, Clarendon, Oxford.
1998, Fan, J. and Shen, C., "Statitical Simulation of Low-speed Unidirectional Flow in Transition Regime," Proceedings of the 21th International Symposium on Rarefied Gas Dynamics, pp.245-252.
2001, Fan, J., Boyd, I.D. and Cai, C., "Computation of Rarifes Gas Flows Around a NACA0012 Airfoil," AIAA Journal, Vol.39, No.4, pp.618-625.
2002, Sun, Q. and Boyd, I.D., "A Direct Simulation Method for Subsonic, Mircoscale Gas Flows," Journal of Computational Physics, Vol.178, pp.400-425.
2003, Sun, Q., "A Direct Simulation Method for Subsonic, Mircoscale Gas Flows,", Ph.D. Thesis, University of Michigan.
2007, Masters, N.D. and Ye, W., "Octant Flux Splitting Information Preservation DSMC Method for Thermally Driven Flows," Journal of Computational Physics, Vol.226, pp.2044-2062.
2009, Roohi, E. and Darbandi, M., "Extending the Navier-Stokes Solution to Transition Regime in Two-dimensional Micro- and Nanochannel Flows Using Information Preservation Scheme," Physics of Fluids, Vol.21, No.082001, pp.1-12.
2010, Otten, D.L. and Veluda, P., "Inportance Sampling Based Direct Simulation Monte Carlo Method," 10th AIAA/ASME Joint Thermophysics and Heat Transfer Conference, No.5061, pp.1-13.
2011, Yao, Z.H., Zhang, X. and Xue, X.B., "IP-DSMC Method for Micro-scale Flow with Temperature Variation," Applied Mathematical Modelling, Vol.35, pp.2016-2023.
2013, Fei, F. and Fan, J., "A Diffusive Information Preservation Method for Small Knudsen Number Flows," Journal of Computational Physics, Vol.243, pp.179-193.
1991, Koura, K. and Matsumoto, H., "Variable Soft Sphere Molecular Model for Inverse-power-law of Lenard Jones Potential," Physics of Fluids, Vol.3, pp.2459-2465.
2004, Wang, M. and Li, Z., "Simulations for Gas Flows in Microgeometries Using the Direct Simulation Monte Carlo Method," International Journal of Heat and Fluid Flow, Vol.25, pp.975-985.
※ AI-Helper는 부적절한 답변을 할 수 있습니다.