本研究將先對慕尼黑工業大學Heft等人開發之Fastback Drivaer model，以及克蘭菲爾德大學Soares、Rjins等人開發之High-Performance Drivaer model，對Fluent之模擬數據與上述模型之實驗數據進行比對驗證，以此增加模擬數據之可信度。
接著，針對一般車輛與高性能車輛在相同流場條件下，比較因外型差異所產生的空氣動力與穩定性分析。研究中採用 Ansys Fluent 軟體作為計算流體力學工具，並選用 SST k-ω 紊流模型以進行數值模擬，建構矩形外型且具有可調整進出口位置的邊界條件之流體場域。模擬範圍涵蓋從直線(曲率為 0 度)以及從曲率5度之彎道開始以每 2.5 度的步進方式至曲率 15 度進行穩態模擬，提供針對彎道中車輛空氣動力行為的數值驗證與詳細模擬分析，並且由此數據進行一般車輛(Fastback Drivaer model)與高性能車輛(High-Performance Drivaer)之氣動力以及穩定性分析，主要之指標將分為阻力係數C_D與下壓力C_L、空氣動力效率AE與空氣動力平衡AB，以此兩種指標，進行一般與高性能車之氣動力與穩定性比較，並且在最後進行High-Performance Drivaer model之氣動力裝置的調整，並探討調整後之變化。

This study first validates the simulation results from Ansys Fluent by comparing them with experimental data from the Fastback DrivAer model, developed by Heft et al. at the Technical University of Munich, and the High-Performance DrivAer model, developed by Soares and Rijns et al. at Cranfield University. This comparison enhances the credibility of the simulation data.
Subsequently, the aerodynamic and stability differences arising from geometry variations between the Fastback DrivAer model and the High-Performance DrivAer model are compared under identical flow conditions. Ansys Fluent is used as the CFD tool, with the SST k-ω turbulence model adopted for the simulations. A rectangular computational domain with adjustable inlet and outlet boundary conditions is constructed. Steady-state simulations are performed starting from straight-line motion (0-degree curvature), followed by cornering simulations from 5 to 15 degrees of curvature in 2.5-degree increments. These simulations provide numerical validation and in-depth analysis of the aerodynamic behavior of vehicles in cornering conditions. Based on the simulation data, the aerodynamic and stability characteristics of the Fastback model and the High-Performance model are analyzed. The primary evaluation metrics include the drag coefficient (C_D), downforce coefficient (C_L), aerodynamic efficiency (AE), and aerodynamic balance (AB). These indicators are used to compare the aerodynamic performance and stability between the two models. Finally, aerodynamic device modifications are applied to the High-Performance model, and the resulting effects are discussed.

[1]Howell, J. and Le Good, G., "The Influence of Aerodynamic Lift on High Speed Stability," SAE Technical Paper, 1999-01-0651, 1999.
[2]Ahmed, S., Ramm, G., and Faltin, G., "Some Salient Features of the Time-Averaged Ground Vehicle Wake," SAE Technical Paper, 840300, 1984.
[3]Cogotti, A., "A Parametric Study on the Ground Effect of a Simplified Car Model," SAE Technical Paper, 980031, 1998.
[4]Heft, T., Indinger, T., and Adams, N. A., "Investigation of Unsteady Flow Structures in the Wake of a Realistic Generic Car Model," 29th AIAA Applied Aerodynamics Conference, Paper AIAA 2011-3669, June 27-30, 2011, Honolulu, Hawaii, USA.
[5]Heft, T., Indinger, T., and Adams, N. A., "Experimental and Numerical Investigation of the DrivAer Model," ASME 2012, FEDSM2012-72272, July 8-12, 2012, Puerto Rico, USA.
[6]Soares, R. F., Knowles, A., Olives, S. G., Garry, K. et al., "On the Aerodynamics of an Enclosed-Wheel Racing Car: An Assessment and Proposal of Add-On Devices for a Fourth, High-Performance Configuration of the DrivAer Model," SAE Technical Paper, 2018-01-0725, 2018.
[7] Rijns, S., Teschner, T.-R., Blackburn, K., and Brighton, J., "Effects of cornering conditions on the aerodynamic characteristics of a high-performance vehicle and its rear wing" Physics of Fluids, Vol. 36, Article number 045119, 2024.
[8]Rijns, S., Teschner, T.-R., Blackburn, K., and Brighton, J., "Comparative Analysis of RANS and DDES Methods for Aerodynamic Performance Predictions for High Performance Vehicles at Low Ground Clearances," UKACM 2023 Conference (UK Association for Computational Mechanics), Presented 19-21 April 2023, Warwick University, Coventry, UK.
[9] Keogh, J., Barber, T., Diasinos, S., and Doig, G., "Techniques for Aerodynamic Analysis of Cornering Vehicles," SAE Technical Paper, 2015-01-0022, 2015.
[10] Menter, F. R., "Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications," AIAA Journal, Vol. 32, No. 8, pp. 1598-1605, 1994.
[11] Hellsten, A., "Some Improvements in Menter's k-omega SST Turbulence Model," 29th AIAA Fluid Dynamics Conference, June 15-18, 1998, Albuquerque, NM, USA.
[12] Singh, R., "CFD Simulation of NASCAR Racing Car Aerodynamics," SAE Technical Paper, 2008-01-0659, 2008.
[13] Wäschle, A., "The Influence of Rotating Wheels on Vehicle Aerodynamics - Numerical and Experimental Investigations," SAE Technical Paper, 2007-01-0107, 2007.
[14] Nara, K., Tsubokura, M., and Ikeda, J., "A Numerical Analysis of Unsteady Aerodynamics of Formula Car During Dynamic Cornering Motion," Published June 16, 2014.
[15] Hu, X., Zhang, R., Ye, J., Yan, X. et al., "Influence of Different Diffuser Angle on Sedan's Aerodynamic Characteristics," Physics Procedia, Vol. 22, pp. 239-245, 2011.
[16] Keogh, J., Barber, T., Diasinos, S., and Doig, G., "The Aerodynamic Effects on a Cornering Ahmed Body," Journal of Wind Engineering and Industrial Aerodynamics, Vol. 154, pp. 34-46, 2016.
[17] Cooper, K. R. et al., "The Aerodynamic Performance of Automotive Underbody Diffusers," SAE Technical Paper, 980030, 1998.
[18] Katz, J. and Cain, K. P., "Rapid, Low-Cost, Aerodynamic Development of a High-Performance Sports Car," SAE Technical Paper, 2011-01-2821, 2011.
[19] Fukuda, H. et al., "Improvement of Vehicle Aerodynamics by Wake Control," JSAE Review, Vol. 16, No. 2, pp. 151-155, 1995.
[20] Rodi, W.，Comparison of LES and RANS Calculations of the Flow Around Bluff Bodies，1997。
[21] Katz, Joseph，AERODYNAMICS OF RACE CARS，Annual Review of Fluid Mechanics，Vol. 38，No. 1，pp. 27–63，2006。
[22] Jowsey, L., Passmore, M.，Experimental Study of Multiple-Channel Automotive Underbody Diffusers，Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering，Vol. 224，No. 7，pp. 865–879，2010。
[23] Alfonsi, Giancarlo，Reynolds-Averaged Navier–Stokes Equations for Turbulence Modeling，2009。
[24] Hellman, S., et al.，PIV Analysis Comparing Flow Past NASCAR COT Rear Wing and Spoiler Traveling Forward and Backwards，SAE Technical Paper，No. 2011-01-1432，2011。
[25] Rijns, S., Teschner, T.-R., Blackburn, K., and Brighton, J., "Performance Analyses of Active Aerodynamic Load Balancing Designs on High-Performance Vehicles in Cornering Conditions," Physics of Fluids, Vol. 36, Issue 8, Article number 085199, 2024.