Research Papers: Flows in Complex Systems

Experimental and Numerical Aerodynamic Analysis of a Passenger Car: Influence of the Blockage Ratio on Drag Coefficient

[+] Author and Article Information
Armagan Altinisik

TOFAS—FIAT (Turkish Automotive
Factory Incorporated Company),
Yeni Yalova Yolu Cad. No: 574,
Bursa 16369, Turkey
e-mail: armagan.altinisik@tofas.com.tr

Emre Kutukceken

Kemalpaşa Mahallesi Şehit Yüzbaşı
Adem Kutlu Sokak No: 21 Elmadağ,
Ankara 06780, Turkey

Habib Umur

Mechanical Engineering Department,
Faculty of Engineering and Architecture,
Uludag University,
Gorukle Campus,
Bursa 16059, Turkey

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received June 5, 2014; final manuscript received March 22, 2015; published online April 29, 2015. Assoc. Editor: Francine Battaglia.

J. Fluids Eng 137(8), 081104 (Aug 01, 2015) (14 pages) Paper No: FE-14-1288; doi: 10.1115/1.4030183 History: Received June 05, 2014; Revised March 22, 2015; Online April 29, 2015

Experimental and numerical investigations were performed to determine the pressure distributions and the drag forces on a passenger car model. Experiments were carried out with 1/5th scale model FIAT Linea for 20% and ~ 1% blockage ratios in the Uludag University Wind Tunnel (UURT) and in the Ankara Wind Tunnel (ART), respectively. Computational fluid dynamics (CFD) analysis for 1/5th scale model with 0%, 5%, and 20% blockage ratios was performed to validate various blockage correction methods supplementary to the experimental results. Three-dimensional, incompressible, and steady governing equations were solved by STAR-CCM+ code with realizable k–ε two-layer turbulence model. The calculated drag coefficients were in good agreement with the experimental results within 6%. Pressure coefficients on the model surfaces have shown similar trends in the experimental and numerical studies. Some of the existing blockage correction methods were successfully compared in this study and predicted drag coefficients were within ± 5%. The authors propose the continuity and the Sykes blockage correction methods for passenger car models because they are very simple and practical and they can be used economically for engineering applications.

Copyright © 2015 by ASME
Your Session has timed out. Please sign back in to continue.


Yang, Z., Schenkel, M., and Fadler, G. J., 2003,” Corrections for the Pressure Gradient Effect on Vehicle Aerodynamic Drag,” SAE Paper No. 2003-01-0935. [CrossRef]
Aider, J., Franc, J., Beaudoin, O., and Wesfreid, J. E., 2010, “Drag and Lift Reduction of a 3D Bluff-Body Using Active Vortex Generators,” Exp. Fluids, 48(5), pp. 771–789. [CrossRef]
Gustavsson, T., and Melin, T., 2006, “Application of Vortex Generators to a Blunt Body,” TRITA-AVE 13, KTH Engineering Sciences, Stockholm.
Koike, M., Nagayoshi, T., and Hamamoto, N., 2004, “Research on Aerodynamic Drag Reduction by Vortex Generators,” Technical Review No. 16, Mitsubishi Motors Research and Development Office.
Kourta, A., and Gillieron, P., 2009, “Impact of the Automotive Aerodynamic Control on the Economic Issues,” J. Appl. Fluid Mech., 2(2), pp. 69–75.
Kumar, C. R., Chowdary, J. U., and Reddy, K. A., 2011, “Study of Aerodynamic Drag Reduction Using Vortex Generators,” IJAEST, 7(10), pp. 181–183.
Ahmed, S. R., and Ramm, G., 1984, “Salient Features of the Time-Averaged Ground Vehicle Wake,” SAE Paper No. 840300. [CrossRef]
Cogotti, A., 1998, “A Parametric Study of the Ground Effect of a Simplified Car Model,” SAE Technical Paper No. 980031. [CrossRef]
Heft, I. A., Indinger, T., and Adams, A. N., 2012, “Introduction of a New Realistic Generic Car Model for Aerodynamic Investigations,” SAE Paper No. 2012-01-0168. [CrossRef]
Strangfeld, C., Wieser, D., Schmidt, H.-J., Woszidlo, R., Nayeri, C., and Paschereit, C., 2013, “Experimental Study of Baseline Flow Characteristics for the Realistic Car Model DrivAer,” SAE Paper No. 2013-01-1251. [CrossRef]
Cooper, K. R., 1993, “Bluff-Body Aerodynamics as Applied to Vehicles,” J. Wind Eng. Ind. Aerodyn., 49(1–3), pp. 1–21. [CrossRef]
Yang, Z., and Schenkel, M., 2004, “Assessment of Closed-Wall Wind Tunnel Blockage Using CFD,” SAE Paper No. 01-0672. [CrossRef]
Hucho,W.-H., 1998, Aerodynamics of Road Vehicles, 4th ed., SAE International, Warrendale, PA, p. 712.
Watkins, S., Saunders, J. W., and Hoffmann, P. H., 1995, “Turbulence Experienced by Moving Vehicles. Part I. Introduction and Turbulence Intensity,” J. Wind Eng. Ind. Aerodyn., 57(1), pp. 1–17. [CrossRef]
Saunders, J. W., and Mansour, B. R., 2000, “On-Road and Wind Tunnel Turbulence and Its Measurement Using a Four-Hole Dynamic Probe Ahead of Several Cars,” SAE Paper No. 2000-01-0350. [CrossRef]
Cogotti, A., 2008, “Evolution of Performance of an Automotive Wind Tunnel,” J. Wind Eng. Ind., 96(7), pp. 667–700. [CrossRef]
Katz, J., 2006, Race Car Aerodynamics, 2nd ed., Robert Bentley, Cambridge, MA.
Carr, G. W., 1971, “Wind Tunnel Blockage Corrections for Road Vehicle,” MIRA Report No. 1971/4.
Gleason, M. E., 2007, “Detailed Analysis of the Bluff Body Blockage Phenomenon in Closed Wall Wind Tunnels Utilizing CFD,” SAE Technical Paper No. 2007-01-1046. [CrossRef]
Sykes, D. M., 1973, Advances in Road Vehicle Aerodynamics, BHRA Fluid Engineering, Cranfield, UK, pp. 311–321.
Stafford, L. G., 1981, “A Streamline Wind-Tunnel Working Section for Testing at High Blockage Ratios,” J. Wind Eng. Ind. Aerodyn., 9(1–2), pp. 23–31. [CrossRef]
Cowdrey, F., 1968, “Two Topics of Interest in Experimental Industrial Aerodynamics—Part 1: Application of Maskell's Theory of Wind-Tunnel Blockage to Some Large Models, Part 2: Design of Velocity-Profile Grids,” NPL Aero Report No. 1268.
Maskell, E. C., 1965, “A Theory of the Blockage Effects on Bluff Bodies and Stalled Wings in a Closed Wind Tunnel,” ARC R&M, HMSO, London, Report No. 3400.
Hackett, J. E., and Cooper, K. R., 2001, “Extensions to Maskell's Theory for Blockage Effects on Bluff Bodies in a Closed Wind Tunnel,” Aeronaut. J. R. Aero. Soc., 105(1041–1050), pp. 409–418.
Cooper, K. R., Mokry, M., and Gleason, M., 2008, “The Two-Variable Boundary-Interference Correction Applied to Automotive Aerodynamic Data,” SAE Paper No. 2008-01-1204. [CrossRef]
Barlow, J. B., Rae, W. H., and Pope, A., 1999, Low-Speed Wind Tunnel Testing, 3rd ed., Wiley, New York.
Moffat, R. J., 1988, “Describing the Uncertainty in Experimental Results,” Exp. Therm. Fluid Sci., 1(1), pp. 3–17. [CrossRef]
Iaccarino, G., 2001, “Predictions of a Turbulent Separated Flow Using Commercial CFD Codes,” ASME J. Fluids Eng., 123(4), pp. 819–828. [CrossRef]
Williams, J., Quinlan, W. J., Hacket, J. E., Thompson, S. A., Marinaccio, T., and Robertson, A., 1994, “A Calibration Study of CFD for Automotive Shapes and CD,” SAE Technical Paper No. 940323. [CrossRef]
Gaylard, A. P., Baxendale, A. J., and Howell, J. P., 1998, “The Use of CFD to Predict the Aerodynamic Characteristics of Simple Automotive Shapes,” SAE Technical Paper No. 980036. [CrossRef]
Connor, C., Kharazi, A., Walter, J., and Martindale, B., 2006, “Comparison of Wind Tunnel Configurations for Testing Closed-Wheel Race Cars: A CFD Study,” SAE Paper No. 2006-01-3620. [CrossRef]
Mokhtar, W. A., 2008, “Aerodynamics of High-Lift Wings With Ground Effect for Racecars,” SAE Technical Paper No. 2008-01-0656. [CrossRef]
Ahmad, N. E., Abo-Serie, E., and Gaylard, A., 2010, “Mesh Optimization for Ground Vehicle Aerodynamics,” CFD Lett., 2(1), p. 54.
Heinzelmann, B., Indinger, T., Adams, N., and Blanke, R., 2012, “Experimental and Numerical Investigation of the Under Hood Flow With Heat Transfer for a Scaled Tractor-Trailer,” SAE Paper No. 2012-01-0107. [CrossRef]
Regin, F. A., Manimanoharan, M., Reddy, A. B., and Nigam, P., 2013, “Aerodynamic Analysis of Cabriolet Passenger Car: A Design Approach,” SAE Paper No. 2013-01-0037. [CrossRef]
Zhang, Y., Ding, W., and Zhang, Y., 2014, “Aerodynamic Shape Optimization Based on the MIRA Reference Car Model,” SAE Paper No. 2014-01-0603. [CrossRef]
Hanjalic, K., 2005, “Will RANS Survive LES? A View of Perspectives,” ASME J. Fluids Eng., 127(5), pp. 831–839. [CrossRef]
Roy, J. C., Payne, J., and Payne, M. M., 2006, “RANS Simulations of a Simplified Tractor/Trailer Geometry,” ASME J. Fluids Eng., 128(5), pp. 1083–1089. [CrossRef]
Makowski, F. T., and Kim, S.-U., 2000, “Advances in External-Aero Simulation of Ground Vehicles Using the Steady RANS Equations,” SAE Paper No. 2000-01-0484. [CrossRef]
Jakirlic, S., Kutej, L., Basara, B., and Tropea, C., 2014, “Computational Study of the Aerodynamics of a Realistic Car Model by Means of RANS and Hybrid RANS/LES Approaches,” SAE Paper No. 2014-01-0594. [CrossRef]
Cilies, J. A., Issakhanian, E., Jimenez, J., and Iaccarino, G., 2012, “An Aerodynamic Investigation of an Isolated Stationary Formula 1 Wheel Assembly,” ASME J. Fluids Eng., 134(12), p. 021101. [CrossRef]
Veluri, P. S., Roy, C. J., Ahmed, A., Rifki, R., Worley, J. C., and Rectenwald, B., 2009, “Joint Computational/Experimental Aerodynamic Study of a Simplified Tractor/Trailer Geometry,” ASME J. Fluids Eng., 131(8), p. 081201. [CrossRef]
Patankar, S. V., 1980, Numerical Heat Transfer and Fluid Flow, McGraw-Hill , New York.
Shih, T.-H., Liou, W. W., Shabbir, A., Yang, Z., and Zhu, J., 1994, “A New k-ɛ Eddy Viscosity Model for High Reynolds Number Turbulent Flows—Model Development and Validation,” NASA TM Report No. 106721, ICOMP 94-21, CMOTT-94-6.
Shih, T., Liou, W. W., Shabbir, A., Yang, Z., and Zhu, J., 1995, “A New k-ε Eddy Viscosity Model for High Reynolds Number Turbulent Flows,” Comput. Fluids, 24(3), pp. 227–238. [CrossRef]
Mokry, M., 1995, “Wall Interference Correction to Drag Measurements in Automotive Wind Tunnels,” J. Wind Eng. Ind. Aerodyn., 56(2–3), pp. 107–122. [CrossRef]
Yang, Z., Nastov, A., and Schenkel, M., 2005, “Further Assessment of Closed-Wall Wind Tunnel Blockage Using CFD,” SAE Paper No. 2005-01-0868. [CrossRef]
Kang, S. O., Jun, S. O., Park, H. I., Song, K. S., Kee, J. D., Kim, K. H., and Lee, D. H., 2012, “Actively Translating Rear Diffuser Device for the Aerodynamic Drag Reduction of a Passenger Car,” Int. J. Autom.Technol., 13(4), pp. 583–592. [CrossRef]
Singh, S. N., Rai, L., Puri, P., and Bhatnagar, A., 2005, “Effect of Moving Surface on the Aerodynamic Drag of Road Vehicles,” Proc. IMechE Part D: J. Autom. Eng., 219(2), pp. 127–134. [CrossRef]
Rodi, W., 1991, “Experience With Two-Layer Models Combining the k–ε Model With a One-Equation Model Near the Wall,” AIAA Paper No. 91-0216.
CD-Adapco, 2011, StarCCM+ User Guide (Version 6.06.011).
Suria, O. V., Testa, E., Repici, G., Peraudo, P., and Maggiore, P., 2011, “A PEM Fuel Cell Laminar and Turbulent Models Comparison, Aiming at Identifying Small-Scale Plate Channel Phenomena: A Mesh Independent Configuration,” SAE Paper No. 2011-01-1177. [CrossRef]
Marklund, J., and Lofdahl, L., 2012, “Influence of a Diffuser to the Wake Flow of a Passenger Car,” ASME Paper No. FEDSM2012-72353. [CrossRef]
Bagal, V., and Mulemane, A., 2010, “Aerodynamic Drag Simulation and Validation of a Crossover,” SAE Paper No. 2010-01-0757. [CrossRef]
Friedl, C., and Watts, M., 2013, “Drag Coefficient Measurement, CFD Simulation and Validation of an Automotive Body,” SAE Paper No. 2013-01-1363. [CrossRef]
Tsubokura, M., Nakashima, T., Kitayama, M., Ikawa, Y., Doh, D. H., and Kobayashi, T., 2010, “Large Eddy Simulation on the Unsteady Aerodynamic Response of a Road Vehicle in Transient Crosswinds,” Int. J. Heat Fluid Flow, 31(6), pp. 1075–1086. [CrossRef]
Akasaka, K., and Ono, K., 2010, “Development of Rapid Simulation Method for Automotive Aerodynamics,” ASME Paper No. FEDSM-ICNMM2010-30625. [CrossRef]
Chu, C.-R., Chang, C.-Y., Huang, C.-J., Wu, T.-R., Wang, C.-Y., and Liu, M.-Y., 2013,” Windbreak Protection for Road Vehicles Against Crosswind,” J. Wind Eng. Ind. Aerodyn., 116, pp. 61–69. [CrossRef]
Guilmineau, E., Deng, G., and Wackers, J., 2011, “Numerical Simulation With a DES Approach for Automotive Flows,” J. Fluids Struct., 27(5–6), pp. 807–816. [CrossRef]
Guilmineau, E., Chikhaoui, O., Deng, G., and Visonneau, M., 2013, “Cross Wind Effects on a Simplified Car Model by a DES Approach,” Comput. Fluids, 78(2013), pp. 29–40. [CrossRef]
Jindal, S., Khalighi, B., and Laccarino, G., 2005, “Numerical Investigation of Road Vehicle Aerodynamics Using Immersed Boundary RANS Approach,” SAE Paper No. 2005-01-0546. [CrossRef]
Gohlke, M., Beaudoin, J. F., Amielh, M., and Anselmet, F., 2010, “Shape Influence on Mean Forces Applied on a Ground Vehicle Under Steady Cross-Wind,” J. Wind Eng. Ind. Aerodyn., 98(8–9), pp. 386–391. [CrossRef]
Cheng, S. Y., Tsubokura, M., Nakashima, T., Okada, Y., and Nouzawa, T., 2012, “Numerical Quantification of Aerodynamic Damping on Pitching of Vehicle-Inspired Bluff Body,” J. Fluids Struct., 30(2012), pp. 188–204. [CrossRef]
Cheng, S. Y., Tsubokura, M., Okada, Y., Nouzawa, T., Nakashima, T., and Doh, D. H., 2013, “Aerodynamic Stability of Road Vehicles in Dynamic Pitching Motion,” J. Wind Eng Ind. Aerodyn., 122(2013), pp. 146–156. [CrossRef]
Song, K. S., Kang, S. O., Jun, S. O., Park, H. I., Kee, J. D., Kim, K. H., and Lee, D. H., 2012, “Aerodynamic Design Optimization of Rear Body Shapes of a Sedan for Drag Reduction,” Int. J. Automot. Technol., 13(6), pp. 905–914. [CrossRef]
Basara, B., Przulj, V., and Tibaut, P., 2001, “On the Calculation of External Aerodynamics: Industrial Benchmarks,” SAE Paper No. 2001-01-0701. [CrossRef]
Gopal, P., and Senthilkumar, T., 2012, “Aerodynamic Drag Reduction in a Passenger Vehicle Using Vortex Generators With Varying Yaw Angles,” ARPN J. Eng. Appl. Sci., 7(9), pp. 1180–1186.
Jenkins, N. L., 2000, “An Experimental Investigation of the Flow Over the Rear End of a Notchback Automobile Configuration,” SAE Paper No. 2000-01-0489. [CrossRef]
Islam, F., Deker, F., Villiers, E., Jackson, A., Gines, J., Grahs, T., Gehrke, G. A., and Font, J. C., 2009, “Application of Detached-Eddy Simulation for Automotive Aerodynamics Development,” SAE Paper No. 2009-01-0333. [CrossRef]


Grahic Jump Location
Fig. 1

(a) Dimensions of 1/5th scale model (in mm) and (b) Positions and quantities of the pressure holes

Grahic Jump Location
Fig. 2

Scaled view of 1/5th scale model in UURT/ART wind tunnels

Grahic Jump Location
Fig. 8

(a) Streamwise wake velocity profiles at 3 and 30 m/s and (b) comparison of the CFD and the experimental velocity profiles in rear wake

Grahic Jump Location
Fig. 5

Flow patterns: (a) 1/5th model tuft test at UURT (30 m/s) and (b) CFD skin friction distribution

Grahic Jump Location
Fig. 6

(a) Velocity profiles on the model at 30 m/s, (b) comparison of the velocity profiles at 3 m/s and 30 m/s, and (c) comparison of the experimental and CFD velocity profiles

Grahic Jump Location
Fig. 7

Comparison of the boundary layer velocity profiles: (a) with the study of Koike et al. [4] and (b) with the study of Jenkins [68]

Grahic Jump Location
Fig. 3

The y+ distributions on the model wall surfaces (this study)

Grahic Jump Location
Fig. 4

Section of domains for various blockage ratios and sample midsection of the computational domain

Grahic Jump Location
Fig. 12

CFD surface pressure contours and distributions with increasing blockage effect

Grahic Jump Location
Fig. 13

Comparison of 1/5th scale FIAT Linea centerline Cp distributions with various models in the literature

Grahic Jump Location
Fig. 9

Comparison of Cp distributions on model surfaces at different blockage ratios

Grahic Jump Location
Fig. 10

Comparison of the CFD Cp distributions with UURT and ART experimental results

Grahic Jump Location
Fig. 11

Comparison of centerline pressure distribution at rear part of the models with the study of (b) Akasaka and Ono [57] and (a) present study



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In