Turbulence

Bailly, Christophe; Comte-Bellot, Geneviève

doi:10.1007/978-3-319-16160-0

Cited by 54 publications

(23 citation statements)

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“…Hot wire anemometry is a well-established, accurate and reliable technique to measure the flow velocity [22]. The velocity distributions were measured with a home-made X-wire probe, connected to a constant temperature anemometer.…”

Section: Dual Hot-wire Anemometrymentioning

confidence: 99%

LES-based numerical prediction of the trailing edge noise in a small wind turbine airfoil at different angles of attack

et al. 2018

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In this paper, the aerodynamic field around a FX 63-137 airfoil for four angles of attack and low Reynolds numbers was simulated with a Large Eddy Simulation (LES). Following, an acoustic analogy method was employed to calculate the airfoil trailing edge (TE) noise. In this second scheme step, the far-field acoustic pressure was predicted from the LES source terms using two different methods based on Lighthill's analogy: Curle's surface approach and Ffowcs-Williams and Hall's volumetric analogy (FW-Hall). Numerical results have been validated with hot-wire anemometry for the aerodynamic fields, thus verifying the accuracy of the CFD simulation for the prediction of noise propagation to the far field. Additionally, aeroacoustic results were validated with experimental measurements carried out in an anechoic wind tunnel using a frequency analyzer. The FW-Hall formulation shows a better agreement with the experiments, especially in the range of frequencies corresponding to the trailing edge, whereas Curle's analogy overpredicts airfoil sound. An exhaustive analysis of the aerodynamic flow field has been performed in order to better understand the generation mechanisms of the TE noise. The aeroacoustic calculations presented in this work contribute to develop a more reliable and efficient prediction methodology based on the Computational Aeroacoustics Approach (CAA).

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Section: Dual Hot-wire Anemometrymentioning

confidence: 99%

LES-based numerical prediction of the trailing edge noise in a small wind turbine airfoil at different angles of attack

et al. 2018

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“…The target spectrum E tar (k) for the numerical spectrum E (k) is the von Kármán energy spectrum for two-dimensional homogeneous isotropic turbulence [26] which is given by…”

Section: Target Spectrum: Homogeneous and Isotropic Two-dimensionamentioning

confidence: 99%

Two-dimensional isotropic turbulent inflow conditions for vortex particle method

Sharma

Sarradj

2019

Phys. Rev. Fluids

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The unsteady loading on an airfoil due to the inflow turbulence is the primary source of broadband noise in turbomachinery, which makes the modeling of the inflow conditions a crucial task. This Rapid Communication presents an advanced method to model isotropic turbulent inflow conditions for a two-dimensional vortex particle method. The method relies on the classical view of turbulence as a superposition of random vortices convected with the mean flow. The fluctuating velocity is formulated using the scalar potential given by a convolution product which furnishes a solenoidal velocity field. The system is then optimized stochastically to create a realistic turbulence field based on a target energy spectra using an evolutionary optimization algorithm.

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“…These subgrid-scale terms represent the interactions with the missing scales and need to be modeled. Among all these terms, the velocity subgrid-scale tensor T u is dominant [17][18][19], and consequently only this term is considered thereafter. If U R denotes the unknown vector associated with resolved scales (see the sketch of the turbulent kinetic energy Ek in Fig.…”

Section: Variational Multiscale Approach For Large-eddy Simulationmentioning

confidence: 99%

“…The standard closure for T u is provided by the Smagorinsky model [17,19]. Dissipation effects are imposed through the introduction of a turbulent viscosity ν t , and the tensor T u is expressed from the deviatoric part S D of the strain tensor as 8 > < > :…”

Section: Variational Multiscale Approach For Large-eddy Simulationmentioning

confidence: 99%

“…where Δ m is a characteristic scale of the element, and the colon denotes the matrix product. The nominal value of the Smagorinsky constant is taken to be C S 0.18, but this turbulence model is known to be very dissipative [19][20][21]. Several models such as the selective Smagorinsky model [21,22] and the dynamic Smagorinsky model [23] have brought improvements by decreasing the value of this artificial viscosity ν t thanks to the local properties of the flow, without modifying the Laplacian functional form, and thus the large range of resolved scales affected by the subgrid-scale dissipation [24].…”

Section: Variational Multiscale Approach For Large-eddy Simulationmentioning

confidence: 99%

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High-Order Variational Multiscale Model in Finite Elements Applied to the LEISA-2 Configuration

Yser

Bailly

2018

AIAA Journal

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A variational multiscale sugbrid model including an explicit filtering is studied in the framework of an equal-order finite element formulation for solving compressible Navier-Stokes equations in entropy variables. The filtering is here achieved by considering embedded piecewise polynomials, whose implementation is made easier with the use of isoparametric and symmetric elements. A hybrid formulation combining a detached-eddy simulation near the walls is also proposed to be able to tackle realistic industrial configurations. The numerical developments are assessed with the Taylor-Green vortex, by comparison with a reference result provided by direct numerical simulation. Finally, new findings are reported with the direct noise computation of the LEISA-2 configuration, a three-element high-lift airfoil as part of the benchmark for airframe noise computation.

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Turbulence

Cited by 54 publications

References 0 publications

LES-based numerical prediction of the trailing edge noise in a small wind turbine airfoil at different angles of attack

LES-based numerical prediction of the trailing edge noise in a small wind turbine airfoil at different angles of attack

Two-dimensional isotropic turbulent inflow conditions for vortex particle method

High-Order Variational Multiscale Model in Finite Elements Applied to the LEISA-2 Configuration

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