Aerodynamics loads variations of wings with novel heating of top surface: Bioinspiration and experimental study

Hassanalian, Mostafa; Pellerito, Victoria; Sedaghat, Ahmad; Sabri, Farhad; Borvayeh, Leila; Sadeghi, Shiva

doi:10.1016/j.expthermflusci.2019.109884

Cited by 26 publications

(12 citation statements)

References 21 publications

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“…As expected, the temperature differential between dorsal wing and ambient air was greater in the uniformly darker wing of the juvenile gannet (electronic supplementary material, figure S4). Furthermore, supporting our hypothesis and previous work on aerofoils [22–27,30], we found a strong effect of increased dorsal surface temperature on wing flight efficiency. Lift and drag of both gannet wings decreased when heated, resulting in a greater lift-to-drag ratio caused by the steeper decline in drag relative to lift (figures 4 and 5).…”

Section: Resultssupporting

confidence: 92%

“…Yet, given the clear effect of temperature, and the known relationship between feather coloration and wing surface temperature [20–22], we expect a greater increase in flight efficiency for birds that have darker dorsal wings when flying under high solar irradiance. Since the lift-to-drag ratio, corresponding to the glide ratio, is directly related to the distance travelled divided by the altitude lost, a lift-to-drag ratio increase of more than five per cent on a dark wing may have far-reaching consequences for birds travelling over 120 000 km in one year [53].…”

Section: Resultsmentioning

confidence: 99%

“…Simulated flight conditions have shown that aerofoil heating persists even when the wing is in motion [21]. Interestingly, multiple studies on artificial aerofoils have shown that wing surface heating can have both a positive and negative effect on flight efficiency, through changes in both lift and drag [22][23][24][25][26][27][28][29][30]. However, these studies were conducted in flow regimes ranging from laminar to turbulent (Reynolds number Re = 3000-300 000 000), using different aerofoil shapes (symmetrical or non-symmetrical) and imposing different wing surface temperatures of up to 400 K. Whether radiative heating improves the ratio between lift and drag on real bird wings, under realistic flight conditions and wing surface temperatures, remains unknown.…”

Section: Introductionmentioning

confidence: 99%

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The evolution of darker wings in seabirds in relation to temperature-dependent flight efficiency

Rogalla

Nicolaï

Porchetta

et al. 2021

J. R. Soc. Interface.

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Seabirds have evolved numerous adaptations that allow them to thrive under hostile conditions. Many seabirds share similar colour patterns, often with dark wings, suggesting that their coloration might be adaptive. Interestingly, these darker wings become hotter when birds fly under high solar irradiance, and previous studies on aerofoils have provided evidence that aerofoil surface heating can affect the ratio between lift and drag, i.e. flight efficiency. However, whether this effect benefits birds remains unknown. Here, we first used phylogenetic analyses to show that strictly oceanic seabirds with a higher glide performance (optimized by reduced sink rates, i.e. the altitude lost over time) have evolved darker wings, potentially as an additional adaptation to improve flight. Using wind tunnel experiments, we then showed that radiative heating of bird wings indeed improves their flight efficiency. These results illustrate that seabirds may have evolved wing pigmentation in part through selection for flight performance under extreme ocean conditions. We suggest that other bird clades, particularly long-distance migrants, might also benefit from this effect and therefore might show similar evolutionary trajectories. These findings may also serve as a guide for bioinspired innovations in aerospace and aviation, especially in low-speed regimes.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The evolution of darker wings in seabirds in relation to temperature-dependent flight efficiency

Rogalla

Nicolaï

Porchetta

et al. 2021

J. R. Soc. Interface.

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“…Recent studies have suggested that wing surface heating under solar radiation could affect the lift‐to‐drag ratio of a flying bird and that this effect would be stronger in hotter, dark‐winged birds (Hassanalian et al . 2017, 2018a, 2018b, 2019, Rogalla et al . 2019).…”

Section: Thermal Effects Of Wing Coloration On Flight Performancementioning

confidence: 99%

“…Heating experiments on different aerofoil shapes resulted in efficiency increases for some, but not all, shapes (Hassanalian et al . 2019). However, birds morph their wings to stabilize their flight, so wing shape not only differs between species but can be further adjusted to different flight conditions (Lentink et al .…”

Section: Thermal Effects Of Wing Coloration On Flight Performancementioning

confidence: 99%

Thermal effects of plumage coloration

Rogalla

Shawkey

D’Alba

2022

Ibis

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Plumage coloration can have substantial effects on a bird's energy budget. This is because different colours reflect and absorb light differently, affecting the heat loads acquired from solar radiation. We examine the thermal effects of feather coloration on solar heat gain and flight performance and discuss the potential role of plumage colour on a bird's energy budget. Early investigations of the effects of plumage colour on thermoregulation revealed complex interactions between environmental conditions and physical properties of the plumage that may have led to diverse behavioural and physiological adaptations of birds to their thermal environment. While darker feather surfaces absorb more light, and heat more, than light‐coloured surfaces under exposure to the sun, this relationship is not always straightforward when considering heat transfer to the skin. Heat transfer through plumage varies depending on multiple factors, such as feather density and transmission of light. For instance, higher transmissivity of light‐coloured plumage can increase heat loads reaching skin level, while conduction and convection transfer heat from the surface of dark feathers to the skin. Solar heating can affect the metabolic costs of maintaining a constant body temperature, and depending on environmental conditions, colours can have either a positive or negative effect on a bird's energy budget. More specifically, solar heating can be advantageous in the cold but may increase the energetic costs associated with thermoregulation when ambient temperature is high. More recent studies have further suggested that the thermal properties of feather coloration might reduce the energetic costs of flight. This is because surface heating can affect the ratio between lift and drag on a wing. As concluding remarks, we provide future directions for new lines of research that will aid in improving our understanding of the thermal effects of feather coloration on a bird's energy budget, which can potentially explain factors driving colour evolution and distribution patterns in birds.

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Surface temperature effects of solar panels of fixed-wing drones on drag reduction and energy consumption

et al. 2020

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Aerodynamics loads variations of wings with novel heating of top surface: Bioinspiration and experimental study

Cited by 26 publications

References 21 publications

The evolution of darker wings in seabirds in relation to temperature-dependent flight efficiency

The evolution of darker wings in seabirds in relation to temperature-dependent flight efficiency

Thermal effects of plumage coloration

Surface temperature effects of solar panels of fixed-wing drones on drag reduction and energy consumption

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