A numerical study of the acoustic radiation due to eddy current-cryostat interactions

2017 ◽  
Vol 44 (6) ◽  
pp. 2196-2206 ◽  
Author(s):  
Yaohui Wang ◽  
Feng Liu ◽  
Xiaorong Zhou ◽  
Yu Li ◽  
Stuart Crozier
Keyword(s):  
Eddy Current ◽  
Acoustic Radiation ◽  
Numerical Study

scholarly journals A numerical study of microparticle acoustophoresis driven by acoustic radiation forces and streaming-induced drag forces

Lab on a Chip ◽  
2012 ◽  
Vol 12 (22) ◽  
pp. 4617 ◽  
Author(s):  
Peter Barkholt Muller ◽  
Rune Barnkob ◽  
Mads Jakob Herring Jensen ◽  
Henrik Bruus
Keyword(s):  
Acoustic Radiation ◽  
Numerical Study ◽  
Drag Forces ◽  
Induced Drag ◽  
Radiation Forces

Numerical study on corrosion profile estimation of a corroded steel plate using eddy current

2019 ◽  
Vol 15 (9) ◽  
pp. 1151-1164 ◽  
Author(s):  
Sanjeema Bajracharya ◽  
Eiichi Sasaki ◽  
Hiroshi Tamura
Keyword(s):  
Eddy Current ◽  
Steel Plate ◽  
Numerical Study ◽  
Profile Estimation

Experimental and Numerical Study on Dynamic Behavior of Eddy Current Damping with Frequency Dependence

2020 ◽  
Vol 146 (10) ◽  
pp. 04020116
Author(s):  
Zhiguo Shi ◽  
Jiazeng Shan ◽  
Cheng Ning Loong ◽  
Weichao Wu ◽  
Chih-Chen Chang ◽  
...  
Keyword(s):  
Frequency Dependence ◽  
Dynamic Behavior ◽  
Eddy Current ◽  
Numerical Study ◽  
Eddy Current Damping

Numerical Study on the Influence of Microchannel’s Geometry on Sub-Micron Particles Separation Using Acoustophoresis

2020 ◽  
Author(s):  
Tsz Wai Lai ◽  
Sau Chung Fu ◽  
Ka Chung Chan ◽  
Christopher Yu Hang Chao ◽  
Anthony Kwok Yung Law
Keyword(s):  
Acoustic Radiation ◽  
Numerical Study ◽  
Acoustic Streaming ◽  
Particle Separation ◽  
Radiation Force ◽  
Rectangular Microchannel ◽  
Cross Sectional ◽  
Fluid Medium ◽  
Particle Sorting ◽  
Micron Particle

Abstract Application of acoustophoresis to cell and particle separation in microchannel filled with fluid medium has been drawing increasing attention in many disciplines in the past decades due to its high precision and minimum damage to the matters of interest. Previous studies on particle separation often rely on the size-dependent feature of the acoustic radiation force (ARF), while the acoustic streaming effect (ASE) is a hurdle as the particle size goes down. Sub-micron particles circulate according to the streaming vortices and become inseparable from the particles settled on the pressure node. Instead of suppressing the ASE, this study intends to utilize the combined effect of ARF and ASE on sub-micron particle sorting by altering the microchannel’s cross-sectional shapes. The roles of ARF and ASE on particles with 0.2um and 2um in radius in various cross-sectional shapes are studied numerically. The studied geometries include 1. rectangular, 2. trapezoidal, and 3. triangular. The results show that changing the cross-sectional shapes affects the acoustic field’s magnitude and distribution, the streaming patterns, the magnitude of streaming velocity, and the movement of sub-micron particles. In non-rectangular microchannel, sub-micron particles circulate towards and settle at the center of the streaming vortices. This phenomenon shows the potential to manipulate the streaming-dominant particles, thereby enhancing the acoustophoretic particle sorting performance.

A numerical study on eddy current signal characteristics of imitative stress corrosion cracks

2017 ◽  
Vol 55 (2) ◽  
pp. 257-269 ◽  
Author(s):  
Cherdpong Jomdecha ◽  
Wenlu Cai ◽  
Shejuan Xie ◽  
Zhenmao Chen ◽  
Peng Li
Keyword(s):  
Stress Corrosion ◽  
Eddy Current ◽  
Numerical Study ◽  
Current Signal ◽  
Signal Characteristics

Numerical study of acoustic radiation due to a supersonic turbulent boundary layer

2014 ◽  
Vol 746 ◽  
pp. 165-192 ◽  
Author(s):  
Lian Duan ◽  
Meelan M. Choudhari ◽  
Minwei Wu
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Numerical Simulations ◽  
Surface Pressure ◽  
Free Stream ◽  
Acoustic Radiation ◽  
Numerical Study ◽  
Near Field ◽  
Pressure Fluctuations ◽  
Spatial Coherence

AbstractDirect numerical simulations are used to examine the pressure fluctuations generated by fully developed turbulence in a Mach 2.5 turbulent boundary layer, with an emphasis on the acoustic fluctuations radiated into the free stream. Single- and multi-point statistics of computed surface pressure fluctuations show good agreement with measurements and numerical simulations at similar flow conditions. Consistent with spark shadowgraphs obtained in free flight, the quasi-homogeneous acoustic near field in the free-stream region consists of randomly spaced wavepackets with a finite spatial coherence. The free-stream pressure fluctuations exhibit important differences from the surface pressure fluctuations in amplitude, frequency content and convection speeds. Such information can be applied towards improved modelling of boundary layer receptivity in conventional supersonic facilities and, hence, enable a better utilization of transition data acquired in such wind tunnels. The predicted acoustic characteristics are compared with the limited available measurements. Finally, the numerical database is used to understand the acoustic source mechanisms, with the finding that the supersonically convecting eddies that can directly radiate to the free stream are confined to the buffer zone within the boundary layer.

Some New Results for the Study of Acoustic Radiation within a Uniform Subsonic Flow Using Boundary Integral Method

2012 ◽  
Vol 488-489 ◽  
pp. 383-395 ◽  
Author(s):  
M. Beldi ◽  
A. Maghrebi
Keyword(s):  
Green Function ◽  
Integral Representation ◽  
Singular Integrals ◽  
Subsonic Flow ◽  
Acoustic Radiation ◽  
Numerical Study ◽  
Integral Formula ◽  
Uniform Flow ◽  
Boundary Integral ◽  
Boundary Integral Method

In this paper, a reformulation of the Helmholtz integral equation for tridimesional acoustic radiation in a uniform subsonic flow is presented. An extension of the Sommerfeld radiation condition, for a free space in a uniform movement, makes possible the determination of the convected Green function, the elementary solution of the convected Helmholtz equation. The gradients of this convected Green function are, so, analyzed. Using these results, an integral representation for the acoustic pressure is established. This representation has the advantage of expressing itself in terms of new surface operators, which simplify the numerical study. For the case of a regular surface, the evaluation of the free term associated with the singular integrals shows that it is independent of the Mach number of the uniform flow. A physical interpretation of this result is offered. A numerical approximation method of the integral representation is developed. Furthermore, for a given mesh, an acoustic discretization criterion in a uniform flow is proposed. Finally, numerical examples are provided in order to validate the integral formula.

scholarly journals POD and Fourier analyses of a fluid-structure-acoustic interaction problem related to interior car noise

2017 ◽  
Vol 18 (2) ◽  
pp. 201
Author(s):  
Éric Gaudard ◽  
Philippe Druault ◽  
Régis Marchiano ◽  
François Van Herpe
Keyword(s):  
Pressure Field ◽  
Acoustic Radiation ◽  
Numerical Study ◽  
Low Frequency ◽  
Wall Pressure ◽  
Aerodynamic Noise ◽  
Frequency Noise ◽  
Post Processing ◽  
Fourier Decomposition ◽  
Frequency Decomposition

In order to approach a flow configuration revealing the aerodynamic noise contribution in the interior of road vehicles due to the A-pillar vortex, a numerical simulation of a Forward Facing Step (FFS) coupled with a vibrating structure is performed. This numerical study is based on a weak coupling of three solvers to compute (i) the flow field in interaction with the FFS, (ii) the vibration of the structure and (iii) the acoustic radiation in the open cavity. The purpose of this work is then to evaluate the ability of two different post-processing methods: Proper Orthogonal Decomposition and Fourier Decomposition to identify the origin of the noise radiated into a cavity surrounded by an unsteady flow. Fourier and POD decompositions are then successively performed to extract the part of the aeroacoustic wall pressure field impacting the upper part of an upward step mainly related to the radiated acoustic pressure in the cavity. It is observed that the acoustic part, extracted from the wavenumber frequency decomposition (Fourier analysis) of the wall pressure field generates a non-negligible part of the interior cavity noise. However, this contribution is of several orders smaller than the one related to the aerodynamic part of the pressure field. Moreover, it is shown that the most energetic part of the pressure field (POD analysis) is due to the shear flapping motion and mainly contributes to the low-frequency noise in the cavity. Such post-processing results are of particular interest for future analyzes related to the noise radiated inside a car.

A Symmetric Galerkin Formulation of the Boundary Element Method for Acoustic Radiation and Scattering

1997 ◽  
Vol 05 (02) ◽  
pp. 219-241 ◽  
Author(s):  
Z. S. Chen ◽  
G. Hofstetter ◽  
H. A. Mang
Keyword(s):  
Boundary Element Method ◽  
Numerical Solution ◽  
Boundary Element ◽  
Integral Equations ◽  
Acoustic Radiation ◽  
Numerical Study ◽  
Three Dimensional ◽  
Galerkin Formulation ◽  
Thin Walled ◽  
Element Method

A symmetric Galerkin formulation of the Boundary Element Method for acoustic radiation and scattering is presented. The basic integral equations for radiation and scattering of sound are derived for structures, which may consist of a combination of a three-dimensional closed part and thin-walled parts. For the numerical solution of these integral equations a Galerkin-type numerical solution scheme is proposed. The evaluation of the weakly-singular and the hypersingular integrals, occurring in this formulation, is addressed briefly. An improved CHIEF-method is employed in order to prevent the singularity of the coefficient matrix of the algebraic system of equations at so-called irregular frequencies. Subsequently, an algorithm for the automatic determination of the number of nodal unknowns at intersections of thin-walled parts of a structure, or of thin-walled parts and the three-dimensional closed part of a structure, is described. The numerical study contains comparisons of analytical solutions for simple academic examples with the numerical results. In addition, a comparison of measured and computed results is presented for a structure, consisting of both a three-dimensional closed part and a thin-walled part.

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