Turbulence in Fluids

Lesieur, M.; Mankbadi, Reda R.

doi:10.1115/1.3173656

Cited by 150 publications

(271 citation statements)

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“…This mechanism can contribute to the generation of spume in the form of streaks. Similar streak-like structures have previously been reported from experiments and numerical simulations near the rigid wall [Lesieur, 2008] and below the free surface [Dhanak and Si, 1999;Tsai, 2001].…”

Section: Numerical Experiments With Imposed Wavessupporting

confidence: 87%

Air‐sea interface in hurricane conditions

Soloviev¹,

Fujimura²,

Matt³

2012

J. Geophys. Res.

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[1] Improving hurricane prediction models requires better understanding of complex processes taking place at the air-sea interface at high wind speeds. The change of the air-sea interaction regime in hurricane conditions has been linked to the mechanism of direct disruption of the air-sea interface by pressure fluctuations working against the surface tension force. This can be achieved through the Kelvin-Helmholtz type instability. In order to investigate this mechanism, we have conducted a series of 3D numerical experiments using a volume of fluid multiphase model. The experiments were initialized with either a flat interface or short wavelets and wind stress applied at the upper boundary of the air layer. The direct disruption of the air-water interface and formation of two-phase transition layer were observed in the numerical model under hurricane force wind. The vertical profiles of density and velocity in the transition layer were consistent with the regime of marginal stability, which permitted estimation of the lower limit on the drag coefficient under hurricane conditions. This limit was appreciably lower than the wave resistance law; though, it was gradually increasing with wind speed. The numerical experiments with imposed short wavelets demonstrated the tearing of wave crests, formation of water sheets and spume ejected into the air, smoothing of the water surface, as well as quasiperiodic structures on the top of wave crests resembling the Tollmien-Schlichting instability. This study can help in developing a framework for combining the effects of the two-phase environment with the contribution to the drag from waves.

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Section: Numerical Experiments With Imposed Wavessupporting

confidence: 87%

Air‐sea interface in hurricane conditions

Soloviev¹,

Fujimura²,

Matt³

2012

J. Geophys. Res.

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“…To compare the relative effect of turbulence on feeding by common and redfin bullies, we set up a series of 12 still and 12 turbulent aquaria. Turbulence can be defined as variation in the direction and magnitude of velocity vectors with time (see Davidson 2004;Lesieur 2008), and using forced air, we created turbulent conditions in experimental aquaria. The 24 aquaria (internal dimension of 39 cm length by 29.5 cm width by 30 cm height) were filled to a depth of 13.5 cm with 18 l of fresh 5% filtered saltwater: 95% spring-water solution.…”

Section: Experimental Designmentioning

confidence: 99%

Feeding ability of a fluvial habitat‐specialist and habitat‐generalist fish in turbulent and still conditions

Vanderpham

Nakagawa

Closs

2013

Ecology of Freshwater Fish

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Species termed ‘habitat‐generalists’ are able to survive across a wide range of habitats, potentially enabled by the plastic behaviours and morphologies of individuals. This study aimed to compare habitat‐related adaptive specialisation in habitat‐generalists and specialists, by comparing feeding abilities of fish under varied hydrodynamic conditions. We compared the proportion of prey consumed by a New Zealand fluvial habitat‐specialist, the redfin bully, to a closely related habitat‐generalist found in fluvial and lacustrine habitats, the common bully, over a 6‐h period in either still or turbulent aquaria. We tested for intraspecific habitat‐specific adaptations by comparing feeding of common bullies from habitats with different hydrodynamic conditions. Within common bullies, previous research has documented a pattern of more lateral‐line system oculoscapular canal pores in fluvial habitats compared to lacustrine ones. By testing for a relationship between total pores and feeding success, we also aimed to identify the adaptive value of an increase in pores in turbulence. We identified decreased feeding (i.e., proportion of prey consumed) by both species in turbulence, but less so for redfin bullies. There was no clear indication of adaptation to habitat type by common bullies, with high variability in feeding by fish from all locations. We also found no statistical relationship between feeding and total oculoscapular canal pores. The results of this study suggest specialised adaptations of a habitat‐specialist to turbulent environments. The variability in feeding activity of common bullies also suggests the importance of behavioural plasticity in the survival of a habitat‐generalist across a wide range of conditions.

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“…To solve the system of eqs (17) and (18), we introduce a scalar potential χ (e.g. Everstine 1981; Kallivokas & Bielak 1993;Lesieur 1997) such that p = −∂ t χ.…”

Section: Outer Corementioning

confidence: 99%

Spectral-element simulations of global seismic wave propagation-I. Validation

Komatitsch¹,

Tromp²

2002

Geophysical Journal International

784

478

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Summary We use a spectral‐element method to simulate seismic wave propagation throughout the entire globe. The method is based upon a weak formulation of the equations of motion and combines the flexibility of a finite‐element method with the accuracy of a global pseudospectral method. The finite‐element mesh honours all first‐ and second‐order discontinuities in the earth model. To maintain a relatively constant resolution throughout the model in terms of the number of grid points per wavelength, the size of the elements is increased with depth in a conforming fashion, thus retaining a diagonal mass matrix. In the Earth's mantle and inner core we solve the wave equation in terms of displacement, whereas in the liquid outer core we use a formulation based upon a scalar potential. The three domains are matched at the inner core and core–mantle boundaries, honouring the continuity of traction and the normal component of velocity. The effects of attenuation and anisotropy are fully incorporated. The method is implemented on a parallel computer using a message passing technique. We benchmark spectral‐element synthetic seismograms against normal‐mode synthetics for a spherically symmetric reference model. The two methods are in excellent agreement for all body‐ and surface‐wave arrivals with periods greater than about 20 s.

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Turbulence in Fluids

Cited by 150 publications

References 0 publications

Air‐sea interface in hurricane conditions

Air‐sea interface in hurricane conditions

Feeding ability of a fluvial habitat‐specialist and habitat‐generalist fish in turbulent and still conditions

Spectral-element simulations of global seismic wave propagation-I. Validation

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