Numerical prediction of turbulent boundary layer noise from a sharp‐edged flat plate

Karimi, Mahmoud; Croaker, Paul; Skvortsov, Alex; Moreau, Danielle; Kessissoglou, Nicole

doi:10.1002/fld.4733

Cited by 16 publications

(6 citation statements)

References 50 publications

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“…Different realizations of the random WPF are generated, where each realization is an input to an acoustic solver based on the BEM. The WPF for the l-th realization can be represented by a set of UWPWs at a node of the boundary element mesh as follows [16,57] p (l) inc (x, ω) =…”

Section: Global Krylov Subspace Solvermentioning

confidence: 99%

“…A total of m = 30 realizations need to be taken into account to achieve an average error of the scattered acoustic pressure of less than 1 dB [16,57]. The solution of the acoustic system with 60 and 90 realizations has also been considered in order to investigate the complexity of the linear solvers with respect to different numbers of right-hand sides.…”

Section: Aeroacoustic Prediction Of An Airfoil In Turbulent Flowmentioning

confidence: 99%

“…Karimi et al [12] found that applying the BEM to periodic structures leads to the formation of a block Toeplitz matrix due to the translational invariance of the free-space Green's function. The method is termed the periodic boundary element method and has been applied to problems with multi-directional periodicity [13], problems involving rotational symmetry [14] and aeroacoustic predictions of airfoils [15,16]. In the latter case, sequences of linear block Toeplitz systems are considered which are block Toeplitz systems with many right-hand sides.…”

Section: Introductionmentioning

confidence: 99%

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Efficient solution of block Toeplitz systems with multiple right-hand sides arising from a periodic boundary element formulation

Jelich¹,

Karimi²,

Kessissoglou³

et al. 2021

Engineering Analysis with Boundary Elements

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Block Toeplitz matrices are a special class of matrices that exhibit reduced memory requirements and a reduced complexity of matrix-vector multiplications. We herein present an efficient computational approach to solve a sequence of block Toeplitz systems arising from a block Toeplitz system with multiple right-hand sides. Two different numerical schemes are implemented for the solution of the sequence of block Toeplitz systems based on global and block variants of the generalized minimal residual (GMRES) method. The performance of the schemes is assessed in terms of the wall clock time of the iterative solution process, the number of multiplications with the block Toeplitz system matrix and the peak memory usage. To demonstrate the method, two numerical examples are presented. In the first case study, aeroacoustic prediction of an airfoil in turbulent flow is examined, which requires multiple solutions of the wall pressure field beneath the turbulent boundary layer. The fluctuating pressure on the surface of the airfoil is synthesized in terms of uncorrelated wall plane waves, whereby each realization of the wall pressure field is an input to the acoustic solver based on the boundary element method (BEM). The total acoustic response from the airfoil in turbulent flow is then obtained from an ensemble average for the number of realizations considered. The number of realizations to yield a converged solution for the wall pressure field leads to a sequence of block Toeplitz systems. The second case study examines the nonlinear eigenvalue analysis of a sonic crystal barrier composed of locally resonant C-shaped sound-hard scatterers. The periodicity of the sound barrier leads to a block Toeplitz system matrix whereas the nonlinear eigenvalue problem requires the solution of sequences of linear systems. The combined technique to solve the sequences of block Toeplitz systems using the proposed variants of the GMRES is shown to yield a computationally efficient approach for flow noise prediction and nonlinear eigenvalue analysis.

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Section: Global Krylov Subspace Solvermentioning

confidence: 99%

Section: Aeroacoustic Prediction Of An Airfoil In Turbulent Flowmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Efficient solution of block Toeplitz systems with multiple right-hand sides arising from a periodic boundary element formulation

Jelich¹,

Karimi²,

Kessissoglou³

et al. 2021

Engineering Analysis with Boundary Elements

Self Cite

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show abstract

“…Correlations between roughness dipoles and surface pressure fluctuations are investigated. Karimi et al 22 employed RANS to estimate turbulent boundary layer parameters such as wall shear stress and so on. And BEM is employed to compute the acoustic scattered from the synthesized wall pressure field.…”

Section: Introductionmentioning

confidence: 99%

Effect of sleeve orifices ratio on flow performance and hydrodynamic noise in the two-stage sleeve control valve

Chen

Qiu

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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Two-stage sleeve control valve has been widely implemented in high-pressure difference hydraulic system, whose function is to reduce hydrodynamic noise. The sleeve with orifices plays a significant role in reducing the hydrodynamic noise. The ratio of orifices diameter between outer sleeve and inner sleeve, Ri is investigated in this paper. The coupling effect of Ri on the flow field and hydrodynamic noise is analyzed deeply by URANS and FW-H model. Furthermore, the pressure, velocity, turbulent kinetic energy and sound pressure level of the flow field are monitored. The results indicate that higher Ri will restrict the flow velocity in the orifices, and the distributed pressure drop of two sleeves will be even. The velocity of flow in the outer sleeve reduces from 130 m/s to 90m/s with the increase of Ri. In addition, larger Ri can reduce the hydrodynamic noise and obtain higher flow capacity. When the Ri is 1.2, the sound power level distributes evenly in the gap, and the radiation intensity of the sound source is the smallest. The study can provide a reference for the design of sleeves in high-pressure control valves.

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“…Stochastic excitations such as turbulent boundary layer (TBL) and acoustic diffuse field (ADF) are widely encountered in transportation systems [21][22][23]. For example, aircraft, satellite, marine vessels, high speed trains and cars are subject to random and non-deterministic excitations throughout their operations.…”

Section: Introductionmentioning

confidence: 99%

Non-negative intensity for planar structures under stochastic excitation

Karimi

Maxit

Meyer

et al. 2020

Journal of Sound and Vibration

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Identification of regions on a vibrating structure which radiate energy to the far field is critical in many areas of engineering. Non-negative intensity is a means to visualize contributions of local surface regions to sound power from vibrating structures. Whilst the non-negative intensity has been used for structures under deterministic excitation due to structural forces or harmonic incident acoustic pressure excitation, it has not been considered for analyzing a structure under stochastic excitation. This work analytically formulates non-negative intensity in the wavenumber domain to investigate the surface areas on a vibrating planar structure that are contributing to the radiated sound power in the far field. The non-negative intensity is derived in terms of the cross spectrum density function of the stochastic field and the sensitivity functions of either the acoustic pressure or normal fluid particle velocity. The proposed formulation can be used for both infinite planar structure and finite plate in an infinite baffle. To demonstrate the technique, a simply supported baffled panel excited by a turbulent boundary layer as well as an acoustic diffuse field is considered and those regions contributing to the radiated sound power are identified. It is demonstrated that the nonnegative intensity distribution is dependent on the stochastic excitation. It is also found that for a panel under stochastic excitation the more the nonnegative intensity distribution is concentrated within the panel surface, the

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Numerical prediction of turbulent boundary layer noise from a sharp‐edged flat plate

Cited by 16 publications

References 50 publications

Efficient solution of block Toeplitz systems with multiple right-hand sides arising from a periodic boundary element formulation

Efficient solution of block Toeplitz systems with multiple right-hand sides arising from a periodic boundary element formulation

Effect of sleeve orifices ratio on flow performance and hydrodynamic noise in the two-stage sleeve control valve

Non-negative intensity for planar structures under stochastic excitation

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