Effect of biomimetic fish forms on minibus aerodynamics: CFD and wind tunnel comparison

Abstract

This research explores the aerodynamic benefits of incorporating biomimetic design principles into commercial minibus bodies by mimicking the cranial morphology of select aquatic species. Inspired by the pronounced head structures and maneuverability of the hump head wrasse, green hump head parrotfish, and flowerhorn fish, three alternative vehicle geometries were developed and compared to a conventional reference model. Computational fluid dynamics (CFD) analyses were performed using the k–ω SST turbulence model, and experimental validation was conducted via wind tunnel testing on a 1:28 scale prototype. Among the configurations, the hump head wrasse-based model exhibited the most favorable aerodynamic behavior, achieving a 16.03% reduction in drag coefficient relative to the baseline. This improvement corresponds to an estimated 8% decrease in fuel consumption, translating to approximately 324 liters of annual savings for a vehicle operating over 45,000 km, and a projected reduction of 748 kg of CO₂ emissions. The results demonstrate that biologically derived shapes can contribute meaningfully to the aerodynamic refinement of ground vehicles, with direct implications for environmental sustainability and energy efficiency.

Keywords

• Biomimetic vehicle design
• Minibus aerodynamics
• CFD simulation
• Wind tunnel testing
• Drag reduction

References

1. [1] Wijegunawardana ID, de Mel WR. Biomimetic designs for automobile engineering: A review. International Journal of Automotive and Mechanical Engineering 2021; 18: 9029-9041.
2. [2] Benyus JM. Biomimicry: Innovation inspired by nature. Perennial, New York, US, 2002.
3. [3] Van Wassenbergh S, Van Manen K, Marcroft TA, Alfaro ME, Stamhuis EJ. Boxfish swimming paradox resolved: Forces by the flow of water around the body promote manoeuvrability. Journal of the Royal Society Interface 2015; 12(103): 20141146.
4. [4] Airbus. Biomimicry: Imitating nature’s best-kept secrets. Airbus. https://www.airbus.com/en/innovation/disruptive-concepts/biomimicry Access date: 15 February 2025.
5. [5] Muthuramalingam M, Puckert DK, Rist U, Bruecker C. Transition delay using biomimetic fish scale arrays. Scientific Reports 2020; 10: 14534.
6. [6] Muthuramalingam M, Villemin LS, Bruecker C. Streak formation in flow over biomimetic fish scale arrays. Journal of Experimental Biology 2019; 222: jeb205963.
7. [7] EarthSky. A kingfisher inspired a bullet train. EarthSky. https://earthsky.org/earth/sunni-robertson-on-how-a-kingfisher-inspired-a-bullet-train/ Access date: 15 February 2025.
8. [8] Turner JS, Soar RC. Beyond biomimicry: What termites can tell us about realizing the living building. Proceedings of the First International Conference on Industrialized Intelligent Construction (I3CON), Loughborough University, Loughborough, UK, 2008.

9. [9] Swim-Swam SSPC. Why is the Speedo Fastskin based on shark skin. Swim-Swam. https://swimswam.com/sspc-why-is-the-speedo-fastskin-based-on-shark-skin/ Access date: 15 February 2025.
10. [10] Morales AT, Tamayo Fajardo JA, González-García H. High-speed swimsuits and their historical development in competitive swimming. Frontiers in Psychology 2019; 10: 2639.
11. [11] Yan YY. Recent advances in computational simulation of macro, meso and micro-scale biomimetics related fluid flow problems. Journal of Bionic Engineering 2007; 4(2): 97-107.
12. [12] Fish FE, Weber PW, Murray MM, Howle LE. The tubercles on humpback whales’ flippers: Application of bio-inspired technology. Integrative and Comparative Biology 2011; 51(1): 203-213.
13. [13] Mercedes Benz. Mercedes Benz media document. Mercedes Benz. https://mercedes-benz-media.co.uk/assets/documents/original/5971-064759700_1218104423.doc Access date: 15 February 2025.
14. [14] Chowdhury H, Islam R, Hussein M, Zaid M, Loganathan B, Alam F. Design of an energy efficient car by biomimicry of a boxfish. Energy Procedia 2019; 160: 40-44.
15. [15] Peng S, Liu X, Li Z, Jiang F. Application of bionics of tiger beetle to aerodynamic optimization of MIRA fastback model. DEStech Transactions on Computer Science and Engineering 2018.
16. [16] Arabacı SK, Pakdemirli M. Aerodynamic improvements of buses inspired by beluga whales. Journal of Applied Fluid Mechanics 2023; 16(12): 2569-2580.
17. [17] Chowdhury H, Loganathan B, Ahmed T, Mustary I, Sonyy SM, Alam F. Aerodynamic design of an energy-efficient light truck by biomimicry. AIP Conference Proceedings 2022; 2681: 020101.
18. [18] Kim JJ, Hong J, Lee SJ. Bio-inspired cab-roof fairing of heavy vehicles for enhancing drag reduction and driving stability. International Journal of Mechanical Sciences 2017; 131-132: 868-879.
19. [19] Ghaffar H, Yusoff H, Ibrahim D, Budin S, Razak MRA. A simulation study of tubercles effect of aerodynamics performance on car rear spoiler. Journal of Physics: Conference Series 2019; 1349: 3-9.
20. [20] Fish FE. Biomimetics: Determining engineering opportunities from nature. Proceedings of the SPIE NanoScience + Engineering, San Diego, CA, US, 2009.
21. [21] Venegas I, Oñate A, Pierart FG, Valenzuela M, Narayan S, Tuninetti V. Efficient mako shark-inspired aerodynamic design for concept car bodies in underground road tunnel conditions. Biomimetics 2024; 9: 448.
22. [22] Kozlov A, Chowdhury H, Mustary I, Loganathan B, Alam F. Bio-inspired design: Aerodynamics of boxfish. Procedia Engineering 2015; 105: 323-328.
23. [23] Vogel S. Life in moving fluids: The physical biology of flow. Princeton University Press, Princeton, New Jersey, US, 1994.
24. [24] Domenici P. Habitat, body design and the swimming performance of fish. Vertebrate biomechanics and evolution. BIOS Scientific Publishers Ltd., Oxford, UK, 2003.
25. [25] Blake RW. Fish functional design and swimming performance. Journal of Fish Biology 2004; 65: 1193-1222.
26. [26] Fulton CJ, Bellwood DR, Wainwright PC. Wave energy and swimming performance shape coral reef fish assemblages. Proceedings of the Royal Society B 2005; 272: 827-832.
27. [27] Alben S, Miller LA, Peng J. Efficient kinematics for jet-propelled swimming. Journal of Fluid Mechanics 2013; 733: 100-133.
28. [28] McLaughlin RL, Grant JWA. Morphological and behavioural differences among brook charr. Environmental Biology of Fishes 1994; 39: 289-300.
29. [29] Thorsen DH, Westneat MW. Diversity of pectoral fin structure and function in fishes. Journal of Morphology 2005; 263: 133-150.
30. [30] Fulton CJ, Johansen JL, Steffensen JF. Energetic extremes in aquatic locomotion by coral reef fishes. PLoS ONE 2013; 8: e54033.
31. [31] Bellwood DR, Wainwright PC. Locomotion in labrid fishes. Coral Reefs 2001; 20: 139-150.
32. [32] Fulton CJ, Bellwood DR, Wainwright PC. The relationship between swimming ability and habitat use in wrasses. Marine Biology 2001; 139: 25-33.
33. [33] Wilcox DC. Formulation of the k–ω turbulence model revisited. AIAA Journal 2008; 46(11): 2823-2838.
34. [34] Camarillo H, Muñoz MM. Weak relationships between swimming morphology and water depth in wrasses and parrotfish. Integrative and Comparative Biology 2020; 60(5): 1309-1319.
35. [35] Sun L, Liao L, Chen M, Li J, An R. Relation between fish morphological differentiation and pressure drag difference. Ecological Indicators 2023; 156: 111071.
36. [36] Mohamed EA, Radhwi MN, Abdel Gawad AF. Computational investigation of aerodynamic characteristics of a bus model. American Journal of Aerospace Engineering 2015; 2(1): 64-73.
37. [37] Ahmad NE, Aboserie E, Gaylard A. Mesh optimization for ground vehicle aerodynamics. CFD Letters 2010; 2(1): 54-65.
38. [38] Belzile M, Patten J, McAuliffe B, Mayda W, Tanguay B. Review of aerodynamic drag reduction devices for heavy trucks and buses. Technical Report, 2012.
39. [39] Hu X, Wong T. A numerical study on rear-spoiler of passenger vehicle. World Academy of Science Engineering and Technology 2011; 81: 636-641.
40. [40] European Automobile Industry Report 2009/2010. European Automobile Manufacturers Association. www.acea.be. Access date: 15 February 2025.
41. [41] Hucho WH. Aerodynamics of road vehicles. SAE International, USA, 1998.
42. [42] Peter S, Fiske JHKS. Lean, light and quiet: Advances in automotive energy efficiency through biomimetic design. SAE Technical Paper, SAE International, 2008.
43. [43] Chateau O, Wantiez L. Site fidelity and activity patterns of a humphead wrasse. Environmental Biology of Fishes 2007; 80(4): 503-508.
44. [44] Weng KC, Pedersen MW, Del Raye GA, Caselle JE, Gray AE. Umbrella species in marine systems. Endangered Species Research 2015; 27(1): 251-263.
45. [45] Sadovy Y, Kulbicki M, Labrosse P, Letourneur Y, Lokani P, Donaldson TJ. The humphead wrasse synopsis. Reviews in Fish Biology and Fisheries 2003; 13(3): 327-364.
46. [46] Froese R, Pauly D. Cheilinus undulatus. FishBase. https://www.fishbase.se/summary/5604 Access date: 15 February 2025.
47. [47] Chan T, Sadovy Y, Donaldson TJ. Bolbometopon muricatum. IUCN Red List of Threatened Species, 2012.
48. [48] Froese R, Pauly D. Bolbometopon muricatum. FishBase, 2006.
49. [49] Datz. The flowerhorn fish. ThinkQuest Library, 2005.
50. [50] Amphilophus trimaculatus. FishBase. https://www.fishbase.se/summary/4692 Access date: 15 February 2025.
51. [51] Mercedes-Benz. Sprinter minibüs. Mercedes-Benz. https://www.mercedes-benz.com.tr/vans/tr/sprinter/minibus Access date: 15 February 2025.
52. [52] Wang Y, Cheng W, Du R, Wang S. Bionic drag reduction for box girders. Energies 2020; 13(17): 4392.
53. [53] Kücüksariyildiz H, Canli E, Carman K. Aerodynamic drag coefficient of agricultural tractor form. Energy 2024; 296: 131167.
54. [54] Liao G, Xue M, Yue L, Yang H, Guo P, Hu X, Wang Z, Ma T. Passive drag reduction optimization. Journal of Applied Fluid Mechanics 2025; 18(6): 1639-1651.
55. [55] Levin J, Chen SH. Aerodynamic of a refrigerated truck. Proceedings of the Institution of Mechanical Engineers Part D 2023.
56. [56] Kim SH, Kim JJ. Study on drag reduction of commercial vehicle. Journal of the Korean Society of Visualization 2023; 21(2): 8-13.
57. [57] Farghaly MB, Sarhan HH, Abdelghany ES. Aerodynamic performance enhancement of heavy trucks. CFD Letters 2023; 15(3).
58. [58] Garcia-Ribeiro D, Bravo-Mosquera PD, Ayala-Zuluaga JA, Martinez-Castañeda DF, Valbuena-Aguilera JS, Cerón-Muñoz HD, Vaca-Rios JJ. Drag reduction of a commercial bus. Proceedings of the Institution of Mechanical Engineers Part D 2023; 237(7): 1623-1636.
59. [59] Jasak H. Error analysis and estimation for finite volume method with applications to fluid flow. PhD Thesis, Imperial College, London, UK, 1996.
60. [60] Ferziger JH, Peric M, Street RL. Computational methods for fluid dynamics. Springer Verlag, 2019.
61. [61] Barlow JB, Rae WH, Pope A. Low-speed wind tunnel testing. John Wiley & Sons, 1999.
62. [62] Fluent ANSYS. Ansys Fluent 14.5 User’s Guide. ANSYS Inc., Canonsburg, PA, US, 2012.
63. [63] Khalighi B, Zhang S, Koromilas C, Balkanyi SR, Bernal LP, Iaccarino G, Moin P. Unsteady wake flow behind a bluff body. SAE Transactions 2001; 1209-1222.
64. [64] Srinivas V. Biomimicry as a tool for aerodynamic drag reduction. Intersect: The Stanford Journal of Science, Technology, and Society 2023; 16(3).
65. [65] Yang CM, Hung JY, Wang YL, Lien YH. Analysis of Mercedes-Benz concept car using biomimicry design. International Journal of Innovation in Management 2019; 7(2): 49-56.
66. [66] Shams Taleghani A, Torabi F. Recent developments in aerodynamics. Frontiers in Mechanical Engineering 2025; 10: 1537383.
67. [67] Sareh P. Inspired by nature, refined by numbers: Formal–functional bioinspiration and intelligent computation in vehicle design. Royal Society Open Science 2025; 12(5).