Skip to main content

Aerodynamic behavior and flow visualization on canonical NACA airfoils at low Reynolds number


Some unmanned aerial vehicles, micro-air vehicles, and small-scale wind turbines operate at Reynolds number values less than \(5 \times 10^5\) based on chord length. However, there are limited data sets characterizing the airfoil performance at Reynolds number spanning \(2\times 10^4 \le Re_c \le 5\times 10^4\). The objective of this study is to investigate the impact of airfoil thickness and camber for canonical NACA airfoils at Reynolds numbers in this range and to correlate the observed aerodynamic behavior with the flow patterns. For this purpose, NACA-0009, 0012, 0021, and 6409 airfoils were used, and all experiments were performed in a water tunnel. A high-precision load cell was utilized to characterize the performance of the airfoils, and the hydrogen bubble flow visualization was used to assess the flow over the airfoils. The results showed that the airfoil thickness and camber significantly influence the aerodynamic performance and a strong dependence on the Reynolds number was observed. Symmetric NACA airfoils exhibited nonlinear lift behavior at Reynolds number below \(4\times 10^4\) as well as abrupt changes in lift values. The cambered airfoil showed some Reynolds number dependence but performed better than its symmetrical counterpart. The aerodynamic performance was correlated with the observed flow features around the airfoils.

Graphical abstract

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12
Fig. 13
Fig. 14


c :

Chord length

\(C_d\) :

Drag coefficient

\(C_l\) :

Lift coefficient

\(Re_c\) :

Reynolds number based on airfoil chord

\(\alpha\) :

Angle of attack


  • Alam MM, Zhou Y, Yang H, Guo H, Mi J (2010) The ultra-low Reynolds number airfoil wake. Exp Fluids 48(1):81–103

    Article  Google Scholar 

  • Anyoji M, Wakui S, Hamada D, Aono H (2018) Experimental study of owl-like airfoil aerodynamics at low Reynolds numbers. J Flow Control Meas Vis 6(03):185

    Google Scholar 

  • Boutilier MSH (2011) Experimental investigation of transition over a NACA 0018 airfoil at a low Reynolds number. Master’s thesis

  • Boutilier MS, Yarusevych S (2012) Separated shear layer transition over an airfoil at a low Reynolds number. Phys Fluids 24(8):084105

    Article  Google Scholar 

  • Burgmann S, Schröder W (2008) Investigation of the vortex induced unsteadiness of a separation bubble via time-resolved and scanning PIV measurements. Exp Fluids 45(4):675–691

    Article  Google Scholar 

  • Burgmann S, Dannemann J, Schröder W (2008) Time-resolved and volumetric PIV measurements of a transitional separation bubble on an sd7003 airfoil. Exp Fluids 44(4):609–622

    Article  Google Scholar 

  • Carmichael B (1981) Low Reynolds number airfoil survey, vol. 1 (NASA-CR-165803)

  • Chitta V, Walters DK, Dhakal TP (2012) Prediction of aerodynamic characteristics for elliptic airfoils in unmanned aerial vehicle applications. Prediction of Aerodynamic Characteristics for Elliptic Airfoils in Unmanned Aerial Vehicle Applications, New York

    Book  Google Scholar 

  • Choudhry A, Arjomandi M, Kelso R (2015) A study of long separation bubble on thick airfoils and its consequent effects. Int J Heat Fluid Flow 52:84–96

    Article  Google Scholar 

  • Demir H, Genç MS (2017) An experimental investigation of laminar separation bubble formation on flexible membrane wing. Eur J Mech- B Fluids 65:326–338.

    Article  Google Scholar 

  • Fitzgerald EJ, Mueller TJ (1990) Measurements in a separation bubble on an airfoil using laser velocimetry. AIAA J 28(4):584–592

    Article  Google Scholar 

  • Gaster M (1969) The structure and behaviour of laminar separation bubbles. Citeseer, Princeton

    Google Scholar 

  • Genç MS, Karasu I, Açıkel HH (2012) An experimental study on aerodynamics of naca2415 aerofoil at low Re numbers. Exp Thermal Fluid Sci 39:252–264

    Article  Google Scholar 

  • Hu H, Yang Z (2008) An experimental study of the laminar flow separation on a low-Reynolds-number airfoil. J Fluids Eng.

    Article  Google Scholar 

  • Jacobs EN (1932) The aerodynamic characteristics of eight very thick airfoils from tests in the variable density wind tunnel (No. NACA-TR-391)

  • Laitone E (1997) Wind tunnel tests of wings at Reynolds numbers below 70 000. Exp Fluids 23(5):405–409

    Article  Google Scholar 

  • Lian Y, Shyy W (2007) Laminar-turbulent transition of a low Reynolds number rigid or flexible airfoil. AIAA J 45(7):1501–1513

    Article  Google Scholar 

  • Lin JM, Pauley LL (1996) Low-Reynolds-number separation on an airfoil. AIAA J 34(8):1570–1577

    Article  MATH  Google Scholar 

  • Menon K, Mittal R (2020) Aerodynamic characteristics of canonical airfoils at low Reynolds numbers. AIAA J 58(2):977–980

    Article  Google Scholar 

  • Miley SJ (1982) Catalog of low-Reynolds-number airfoil data for wind-turbine applications. Tech. rep., Rockwell International Corp., Golden, CO (USA). Rocky Flats Plant

  • Mueller TJ (1985) The influence of laminar separation and transition on low Reynolds number airfoil hysteresis. J Aircr 22(9):763–770

    Article  Google Scholar 

  • Mueller TJ (2000) Aerodynamic measurements at low Reynolds numbers for fixed wing micro-air vehicles. Tech rep, Notre Dame Univ Dept Aerosp Mech Eng

  • O’Meara M, Mueller T (1987) Laminar separation bubble characteristics on an airfoil at low Reynolds numbers. AIAA J 25(8):1033–1041

    Article  Google Scholar 

  • Olson DA, Katz AW, Naguib AM, Koochesfahani MM, Rizzetta DP, Visbal MR (2013) On the challenges in experimental characterization of flow separation over airfoils at low Reynolds number. Exp Fluids 54(2):1–11

    Article  Google Scholar 

  • Ol MV, McAuliffe BR, Hanff ES, Scholz U, Kähler C (2005) Comparison of laminar separation bubble measurements on a low Reynolds number airfoil in three facilities. AIAA paper 5149(1):2005

    Google Scholar 

  • Pope A, John JH (1966) Low-speed wind tunnel testing. Wiley, Hoboken

    Google Scholar 

  • Radespiel RE, Windte J, Scholz U (2007) Numerical and experimental flow analysis of moving airfoils with laminar separation bubbles. AIAA J 45(6):1346–1356

    Article  Google Scholar 

  • Ravi S, Watkins S, Watmuff J, Massey K, Peterson P, Marino M (2012) Influence of large-scale freestream turbulence on the performance of a thin airfoil. AIAA J 50(11):2448–2459

    Article  Google Scholar 

  • Selig MS (1995) Summary of Low-Speed Airfoil Data: Low-Speed Airfoil Test, University of Illinois at Urbana-Champaign. Virginia Beach, Va. SoarTech

  • Seshagiri A, Cooper E, Traub LW (2009) Effects of vortex generators on an airfoil at low Reynolds numbers. J Aircr 46(1):116–122

    Article  Google Scholar 

  • Smits AJ, Lim T (2012) Flow Visualization, Techniques and Examples. World Scientific, Singapore

    Book  Google Scholar 

  • Spedding G, Hedenström A, McArthur J, Rosén M (2008) The implications of low-speed fixed-wing Aerofoil measurements on the analysis and performance of flapping bird wings. J Exp Biol 211(2):215–223

    Article  Google Scholar 

  • Tani I (1964) Low-speed flows involving bubble separations. Prog Aerosp Sci 5:70–103

    Article  Google Scholar 

  • Tank J, Smith L, Spedding G (2017) On the possibility (or lack thereof) of agreement between experiment and computation of flows over wings at moderate Reynolds number. Interface focus 7(1):20160076

    Article  Google Scholar 

  • Traub LW, Coffman C (2019) Efficient low-reynolds-number airfoils. J Aircr 56(5):1987–2003

    Article  Google Scholar 

  • Wang S, Zhou Y, Alam MM, Yang H (2014) Turbulent intensity and Reynolds number effects on an airfoil at low Reynolds numbers. Phys Fluids 26(11):115107

    Article  Google Scholar 

  • Winslow J, Otsuka H, Govindarajan B, Chopra I (2018) Basic understanding of airfoil characteristics at low Reynolds numbers (104–105). J Aircr 55(3):1050–1061.

    Article  Google Scholar 

  • Xia T, Dong H, Yang L, Liu S, Jin Z (2021) Investigation on flow structure and aerodynamic characteristics over an airfoil at low Reynolds number-a review. AIP Adv 11(5):050701

    Article  Google Scholar 

  • Yang Z, Haan F, Hu H, Ma H (2007) An experimental investigation on the flow separation on a low-Reynolds-number airfoil. In 45th AIAA aerospace sciences meeting and exhibit, p 275

  • Yarusevych S, Sullivan PE, Kawall JG (2009) On vortex shedding from an airfoil in low-Reynolds-number flows. J Fluid Mech 632:245–271

    Article  MATH  Google Scholar 

  • Zhang Y, Zhou Z, Wang K, Li X (2020) Aerodynamic characteristics of different airfoils under varied turbulence intensities at low Reynolds numbers. Appl Sci.

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Vibhav Durgesh.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Durgesh, V., Johari, H. & Garcia, E. Aerodynamic behavior and flow visualization on canonical NACA airfoils at low Reynolds number. J Vis (2023).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • DOI:


  • Low Reynolds number
  • Flow visualization
  • Laminar separation bubble
  • NACA Airfoil