Radiation and Outflow Boundary Conditions for Direct Computation of Acoustic and Flow Disturbances in a Nonuniform Mean Flow

Tam, Christopher K. W.; Dong, Zhong

doi:10.1142/s0218396x96000040

Cited by 293 publications

(149 citation statements)

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“…II.B. The radiation boundary conditions of Tam and Dong [23] are implemented at the other boundaries. They are applied to the last three rows at each boundary point.…”

Section: A Linearized Euler Equations Solvermentioning

confidence: 99%

Time-Domain Simulations of Outdoor Sound Propagation with Suitable Impedance Boundary Conditions

et al. 2011

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Finite difference time-domain methods are attractive for the study of broadband outdoor noise propagation, because they can accurately take into account both atmospheric and ground effects. Moreover, these methods allow moving sound sources to be modeled, which can be interesting in the context of transportation noise. A recently proposed method to obtain an impedance boundary condition is implemented in a linearized Euler equations solver. A long-range propagation configuration in a two-dimensional geometry is studied in homogeneous conditions and in downward-refracting conditions with an impedance ground over a distance of 500 m. Two impedance models corresponding to a grassy ground and to a snow-covered ground are considered. Numerical results are compared in the time domain to an analytical solution in homogeneous conditions and to results from a ray-tracing code in downward-refracting conditions. Near the ground, surface waves are detected in the two cases and are the dominant arrivals in the homogeneous case.

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“…II.B. The radiation boundary conditions of Tam and Dong [23] are implemented at the other boundaries. They are applied to the last three rows at each boundary point.…”

Section: A Linearized Euler Equations Solvermentioning

confidence: 99%

Time-Domain Simulations of Outdoor Sound Propagation with Suitable Impedance Boundary Conditions

et al. 2011

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“…The boundary condition in the spanwise direction is periodic and is implemented in such a way as to allow the use of the 11-point differencing and filter stencils up to the lateral boundaries. At the lateral radiation boundaries in the and directions, a three-dimensional generalization of Tam and Dong's [26] 2-D far-field radiation condition is used. Details on the 3-D formulation can be found in Bogey and Bailly [27].…”

Section: Numerical Aspectsmentioning

confidence: 99%

Direct Noise Computation of the Turbulent Flow Around a Zero-Incidence Airfoil

2008

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A large eddy simulation of the flow around a NACA 0012 airfoil at zero incidence is performed at a chord-based Reynolds number of 500,000 and a Mach number of 0.22. The aim is to show that high-order numerical schemes can successfully be used to perform direct acoustic computations of compressible transitional flow on curvilinear grids. At a Reynolds number of 500,000, the boundary layers around the airfoil transition from an initially laminar state to a turbulent state before reaching the trailing edge. Results obtained in the large eddy simulation show a well-placed transition zone and turbulence levels in the boundary layers that are in agreement with experimental data. Furthermore, the radiated acoustic field is determined directly by the large eddy simulation, without the use of an acoustic analogy. Third-octave acoustic spectra are compared favorably with experimental data.

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“…An 11-point fourth-order spatial filtering is applied as well. Tam and Dong's [51] radiation boundary condition is set at the inlet of the computational domain, while outflow boundary conditions are imposed at the outlets.…”

Section: B Computational Setupmentioning

confidence: 99%

Turbulence Generation from a Sweeping-Based Stochastic Model

et al. 2014

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Stochastic methods are widely used because they constitute a low-cost computational-fluid-dynamics approach to synthesize a turbulent velocity field from time-averaged variables of a flowfield. A new combined stochastic method based on the sweeping hypothesis is introduced in this paper. This phenomenon, stating that inertial range structures are advected by the energy containing eddies, is known to be an important mechanism of the turbulent velocity field decorrelation process. The proposed method presents the advantage of being easily implementable and applicable to any three-dimensional configuration as long as a steady Reynolds-averaged Navier-Stokes computation of the flow is available and assuming that the considered turbulence physics is compatible with the hypotheses made to build the current numerical model. The developed method is applied on a subsonic round cold free jet. The validation study shows that the synthesized turbulent velocity fields reproduce statistical features of the flow, such as two-point twotime velocity correlation functions, comparable to those found experimentally and integrates shear effects of the mean flow. The mean convection velocity of the turbulent structures is also correctly modeled. In addition, the turbulent kinetic energy spatial distribution is preserved by the stochastic method.

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Radiation and Outflow Boundary Conditions for Direct Computation of Acoustic and Flow Disturbances in a Nonuniform Mean Flow

Cited by 293 publications

References 0 publications

Time-Domain Simulations of Outdoor Sound Propagation with Suitable Impedance Boundary Conditions

Time-Domain Simulations of Outdoor Sound Propagation with Suitable Impedance Boundary Conditions

Direct Noise Computation of the Turbulent Flow Around a Zero-Incidence Airfoil

Turbulence Generation from a Sweeping-Based Stochastic Model

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