نتایج جستجو برای: acoustic analogy

تعداد نتایج: 103148  

2012
Yiping Wang Zhengqi Gu Weiping Li Xiaohui Lin

The aerodynamic noise radiation from a side view mirror (SVM) in the high-speed airflow is calculated by the combination of unsteady incompressible fluid flow analysis and acoustic analysis. The transient flow past the generic SVM is simulated with variable turbulence model, namely DES Detached Eddy Simulation and LES (Large Eddy Simulation). Detailed velocity vectors and contour plots of the t...

Journal: :Physics of Fluids 2022

We present a physical model and numerical method based on space- time-dependent Galilean-type coordinate transformation to simulate acoustic waves in the presence of an accelerating background flow field with sonic transition. Kinematically, is designed so as maintain well-posedness transformed wave equation, which solved fixed computational domain using standard finite differences. Considering...

2006
A. Wixforth Ch. Strobl Ch. Gauer A. Toegl J. Scriba

Surface acoustic waves are used to actuate and process smallest amounts of fluids on the planar surface of a piezoelectric chip. Chemical modification of the chip surface is employed to create virtual wells and tubes to confine the liquids. Lithographically modulated wetting properties of the surface define a fluidic network, in analogy to the wiring of an electronic circuit. Acoustic radiation...

Journal: :Analytical and bioanalytical chemistry 2004
Achim Wixforth Christoph Strobl Ch Gauer A Toegl J Scriba Z v Guttenberg

Surface acoustic waves are used to actuate and process smallest amounts of fluids on the planar surface of a piezoelectric chip. Chemical modification of the chip surface is employed to create virtual wells and tubes to confine the liquids. Lithographically modulated wetting properties of the surface define a fluidic network, in analogy to the wiring of an electronic circuit. Acoustic radiation...

2015
Vasily A. Semiletov Sergey A. Karabasov

The Adjoint Linearised Euler Solver of Karabasov and Hynes (2006), which includes an efficient iterative solution of linearised Euler equations in the frequency domain, has been extended to a 3D framework. Numerical tests performed for the problem of sound scattering from an axi-symmetric Gaussian jet flow show a very good performance of the method for a range of frequencies and observer angles...

The current study presents the results of the aerodynamic noise prediction of the flow field around a NACA 0012 airfoil at a chord-based Reynolds number of 100,000 and at 8.4 degree angle of attack. An incompressible Large Eddy Simulation (LES) turbulence model is applied to obtain the instantaneous turbulent flow field. The noise prediction is performed by the Ffowcs Williams and Hawkings (FW-...

2014
Dimitri Papamoschou Juntao Xiong Feng Liu

The Lighthill acoustic analogy indicates that substantial noise reduction is possible in high-speed jets by reducing the radiation efficiency. This entails reducing the convective Mach number of the eddies whose footprint is sensed in the near pressure field. In dualstream jets, local reduction in convective Mach number is possible by inducing asymmetry in the plume that redistributes the most ...

1999
DAVID P. LOCKARD

The use of computational techniques in the area of acoustics is known as computational aeroacoustics and has shown great promise in recent years. Although an ultimate goal is to use computational simulations as a virtual wind tunnel, the problem is so complex that blind applications of traditional algorithms are typically unable to produce acceptable results. The phenomena of interest are inher...

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