Physical
Hydrodynamics

Guyon, E.; Hulin, Jean-Pierre; Petit, Lionel; Mitescu, CD; Jankowski, D. F.

doi:10.1115/1.1497485

Cited by 51 publications

(46 citation statements)

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“…This significantly simplifies the governing equations such as those describing the conservation of mass (Eqn 1) and momentum (Eqn 2) (e.g. Anderson, 1991;White, 1991;Guyon et al, 2001;Tritton, 2005):…”

Section: Materials and Methods Ns Equation Of A Fly In Forward Flappimentioning

confidence: 99%

“…Its original context was as a measure of dimensionless shedding frequency for a bluff body undergoing von Kármán shedding in a constant flow (e.g. Guyon et al, 2001), but is has additional uses in biological fluid dynamics (Triantafyllou et al, 1993;Taylor et al, 2003). For example, it is proportional to the tangent of maximal induced angle of attack by a flapping wing or fin when the stroke plane is perpendicular to the direction of motion (Taylor et al, 2003;Lentink et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Biofluiddynamic scaling of flapping, spinning and translating fins and wings

Lentink

Dickinson

2009

Journal of Experimental Biology

159

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SUMMARYOrganisms that swim or fly with fins or wings physically interact with the surrounding water and air. The interactions are governed by the morphology and kinematics of the locomotory system that form boundary conditions to the Navier-Stokes (NS) equations. These equations represent Newton's law of motion for the fluid surrounding the organism. Several dimensionless numbers, such as the Reynolds number and Strouhal number, measure the influence of morphology and kinematics on the fluid dynamics of swimming and flight. There exists, however, no coherent theoretical framework that shows how such dimensionless numbers of organisms are linked to the NS equation. Here we present an integrated approach to scale the biological fluid dynamics of a wing that flaps, spins or translates. Both the morphology and kinematics of the locomotory system are coupled to the NS equation through which we find dimensionless numbers that represent rotational accelerations in the flow due to wing kinematics and morphology. The three corresponding dimensionless numbers are (1) the angular acceleration number, (2) the centripetal acceleration number, and (3) the Rossby number, which measures Coriolis acceleration. These dimensionless numbers consist of length scale ratios, which facilitate their geometric interpretation. This approach gives fundamental insight into the physical mechanisms that explain the differences in performance among flapping, spinning and translating wings. Although we derived this new framework for the special case of a model fly wing, the method is general enough to make it applicable to other organisms that fly or swim using wings or fins.

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Section: Materials and Methods Ns Equation Of A Fly In Forward Flappimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Biofluiddynamic scaling of flapping, spinning and translating fins and wings

Lentink

Dickinson

2009

Journal of Experimental Biology

159

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“…As R(x) is constant all along the channel the pressure gradient in both fluids are equal: This set of equations is closed by defining the boundary conditions, namely: the velocity and the tangential components of the stress tensor are continuous at the interface and there is no slip at the walls for both fluids (Guyon et al 2001;Bird et al 2002). Note that the viscosity surface term is neglected in the shear stress tensor (Guillot et al 2006).…”

Section: Properties Of the Parallel Flowmentioning

confidence: 99%

Towards a continuous microfluidic rheometer

Guillot

Moulin

Kötitz

et al. 2008

Microfluid Nanofluid

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In a previous paper we presented a way to measure the rheological properties of complex fluids on a microfluidic chip (Guillot et al., Langmuir 22:6438, 2006). The principle of our method is to use parallel flows between two immiscible fluids as a pressure sensor. In fact, in a such flow, both fluids flow side by side and the size occupied by each fluid stream depends only on both flow rates and on both viscosities. We use this property to measure the viscosity of one fluid knowing the viscosity of the other one, both flow rates and the relative size of both streams in a cross-section. We showed that using a less viscous fluid as a reference fluid allows to define a mean shear rate with a low standard deviation in the other fluid. This method allows us to measure the flow curve of a fluid with less than 250 lL of fluid. In this paper we implement this principle in a fully automated set up which controls the flow rate, analyzes the picture and calculates the mean shear rate and the viscosity of the studied fluid. We present results obtained for Newtonian fluids and complex fluids using this set up and we compare our data with cone and plate rheometer measurements. By adding a mixing stage in the fluidic network we show how this set up can be used to characterize in a continuous way the evolution of the rheological properties as a function of the formulation composition. We illustrate this by measuring the rheological curve of four formulations of polyethylene oxide solution with only 1.3 mL of concentrated polyethylene oxide solution. This method could be very useful in screening processes where the viscosity range and the behavior of the fluid to an applied stress must be evaluated.

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“…Non-dimensionalization allowed us to objectively quantify the scale effects (Guyon et al, 2001) of a flapping foil. We followed an approach described in Lentink and Gerritsma (Lentink and Gerritsma, 2003) that is consistent from hovering fight, with zero dimensionless wavelength, to fast forward flight, for which the dimensionless wavelength approaches infinity.…”

Section: Parameterization Of the Flapping Foilmentioning

confidence: 99%

“…In three dimensions the vortex dynamic complexity is further increased (e.g. Buchholz and Smits, 2006;von Ellenrieder et al, 2003) by processes such as vortex stretching (Guyon et al, 2001). High Reynolds numbers also facilitate three-dimensional instabilities that can result, for example, in coherent vortices with a turbulent structure (e.g.…”

Section: Introductionmentioning

confidence: 99%

Vortex-wake interactions of a flapping foil that models animal swimming and flight

Lentink

Muijres

Donker-Duyvis

et al. 2008

Journal of Experimental Biology

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SummaryThe fluid dynamics of many swimming and flying animals involves the generation and shedding of vortices into the wake. Here we studied the dynamics of similar vortices shed by a simple two-dimensional flapping foil in a soap-film tunnel. The flapping foil models an animal wing, fin or tail in forward locomotion. The vortical flow induced by the foil is correlated to (the resulting) thickness variations in the soap film. We visualized these thickness variations through light diffraction and recorded it with a digital high speed camera. This set-up enabled us to study the influence of foil kinematics on vortex-wake interactions. We varied the dimensionless wavelength of the foil (*=4-24) at a constant dimensionless flapping amplitude (A*=1.5) and geometric angle of attack amplitude (A ␣,geo =15°). The corresponding Reynolds number was of the order of 1000. Such values are relevant for animal swimming and flight.We found that a significant leading edge vortex (LEV) was generated by the foil at low dimensionless wavelengths (*<10). The LEV separated from the foil for all dimensionless wavelengths. The relative time (compared with the flapping period) that the unstable LEV stayed above the flapping foil increased for decreasing dimensionless wavelengths. As the dimensionless wavelength decreased, the wake dynamics evolved from a wavy von Kármán-like vortex wake shed along the sinusoidal path of the foil into a wake densely packed with large interacting vortices. We found that strongly interacting vortices could change the wake topology abruptly. This occured when vortices were close enough to merge or tear each other apart. Our experiments show that relatively small changes in the kinematics of a flapping foil can alter the topology of the vortex wake drastically.

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Physical Hydrodynamics

Cited by 51 publications

References 0 publications

Biofluiddynamic scaling of flapping, spinning and translating fins and wings

Biofluiddynamic scaling of flapping, spinning and translating fins and wings

Towards a continuous microfluidic rheometer

Vortex-wake interactions of a flapping foil that models animal swimming and flight

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