Active acoustic cloaking in a convected flow field

Eggler, Daniel; Karimi, Mahmoud; Kessissoglou, Nicole

doi:10.1121/1.5119225

Cited by 11 publications

(4 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The derivation of the source coefficient in the form (34) involves expanding the Green's function in the integrand of ( 22) using the first case of the addition formula (26), which holds only for x ∈ R 3 \ D with D defined in (33). From (20), the Kirchhoff-Helmholtz integral equation is identically zero for x ∈ R 3 \ C. For multipolar sources of sufficiently high order, one can thus deduce that u d (x), in the form ( 2) and ( 35), vanishes identically for x ∈ R 3 \(C ∪ D), which is the region exterior to the imaginary spheres centred at the active sources. The radiation-free condition (26) to expand the wavefunctions as one centred at the source at x (the green dot).…”

Section: Supplementary Materialsmentioning

confidence: 96%

See 1 more Smart Citation

Silence is bliss in a Platonic relationship

Yeung¹,

Shearer²,

Parnell³

2021

Preprint

View full text Add to dashboard Cite

We describe an effective active cloaking strategy for the scalar Helmholtz equation in three dimensions where multipole active sources are located at the vertices of the Platonic solids. A "silent zone" is created interior to the imaginary Platonic solid and only the incident field remains in a defined region exterior to the silent zone and active source configuration. This distribution of the sources ensures that the implementation of the cloaking strategy is extremely efficient. In particular, once the multipole source amplitudes required at a single source location are determined, the other source amplitudes can be calculated by simple post-processing involving multiplication of the multipole source vector by a rotation matrix. The general nature of the problem means that the technique is relevant to any scalar wave field, including both acoustics and electromagnetism.

show abstract

Section: Supplementary Materialsmentioning

confidence: 96%

“…An illustration of the relation between various methods in acoustics was provided by Cheer [16]. Specific choices of sources can ensure quiet zones and illusions [11,17] and recent work has optimised control sources to reduce the scattered field in passive scenarios and cases with flow for the cloaking of specific objects [18][19][20][21].…”

mentioning

confidence: 99%

Silence is bliss in a Platonic relationship

Yeung¹,

Shearer²,

Parnell³

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…The current literature has significantly addressed the idea of the active control of Helmholtz scalar fields in broad applications. These include, but are not limited to, active noise control [2][3][4], personal sound zones or multizone sound reproduction [5][6][7], active acoustic cloaking [2,[8][9][10], remote sensing [11,12] and metamaterial design [13][14][15]. Active sound control techniques are becoming increasingly ubiquitous to enhance sound-based systems [16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Feasibility analysis for active near/far field acoustic pattern synthesis in free space and shallow water environments

Egarguin

Onofrei

et al. 2021

Acta Acust.

View full text Add to dashboard Cite

In this paper, a detailed sensitivity and feasibility analysis of the active manipulation scheme for scalar Helmholtz fields proposed in our previous works, in both free space and constant-depth homogeneous ocean environments, is presented. We apply the method of moments (MoM) together with Tikhonov regularization with the Morozov discrepancy principle to investigate the effects of varying the problem parameters to the accuracy and feasibility of the proposed active field control strategy. We discuss the feasibility of the active scheme (with respect to power budget, control accuracy and process error) as a function of the frequency, the distance between the control region and the source, the mutual distance between the control regions, and the size of the control region. Process error is considered as well to investigate the possibility of an accurate active control in the presence of manufacturing or feeding noise. The numerical simulations show the accuracy of the active field control scheme and indicate some challenges and limitations for its physical implementation.

show abstract

“…Several researchers have recently deliberated on the subject. For example, in a series of research papers, Eggler and coworkers theoretically studied active acoustic cloaking for a rigid cylinder in a convected flow field with circumferentially arranged monopole control sources and error sensors 55 , active optimal noise cloaking of rigid and elastic cylindrical shells with circumferentially arranged external monopole control sources or directly applied structural control forces and discrete error sensors 56 , and active optimal acoustic cloaking and illusions of 3D sound-hard bodies (e.g., rigid spheres and cubes) with spherically arranged external discrete monopole control sources and error sensors 57 . It was demonstrated that overlooking the flow effects can cause amplification of the controlled acoustic field due to the constructive interference between the secondary and primary scattered fields.…”

mentioning

confidence: 99%

A novel smart hybrid multimorph piezoelectric spherical shell cloak for broadband near-perfect underwater acoustic camouflage applications

Hasheminejad,

Kasaeisani

2024

Sci Rep

View full text Add to dashboard Cite

Non-visual auditory camouflage plays a major role in the art of underwater deception. In this work, a hybrid active/semi-active omnidirectional cloaking shell structure composed of alternate complementary piezoelectric and smart viscoelastic (PZT/SVE) actuator layers is proposed that can effectively conceal a three dimensional underwater macroscopic object from broadband incident sound waves. The smart hybrid structure incorporates a finite sequence of fully active parallel-connected multimorph PZT constraining layers inter-stacked with semi-active SVE core layers both of which are collaboratively operative in the framework of a Particle Swarm Optimized (PSO) multiple-input multiple-output active damping control (MIMO-ADC) scheme. The elasto-acoustic modeling of the problem is conducted by coupling the spatial state space methodology based on the classical three-dimensional exact piezoelasticity theory with the wave equations for the inner and outer acoustic domains. The acoustic cloaking performance of proposed configuration is evaluated for four distinct classes of highly functional SVE interlayer materials with tunable (field-dependent) rheological properties, namely, magnetorheological elastomer (MRE), shape memory polymer (SMP), electrorheological fluid (ERF), and magnetorheological shear thickening polishing fluid (MRSTPF). Extensive numerical results reveal significant broadband reductions of the far-field backscattering amplitude in the ($$\left|{f}_{\infty }\left(\theta =\pi ,{k}_{\text{ex}}{R}_{\text{ex }}\right)\right|)$$ f ∞ θ = π , k ex R ex ) as well as the percentage error of external cloaked field $$(\%\text{Err})$$ ( % Err ) by incorporating a sufficient number of smart multimorph PZT/SVE material layers. Furthermore, it is concluded that comparable low frequency acoustic cloaking effects is possible without expenditure of any external energy just by employing the entirely inactive MRSTPF-based cloak as an alternative to the semiactive or fully active multimorph PZT/SVE cloaks. The outcome of proposed study can advantageously serve as the first step towards practical development and experimental implementation of future high performance smart acoustic cloaking devices with expanded broadband near-perfect omnidirectional invisibility for three dimensional objects of diverse geometries.

show abstract

Active acoustic cloaking in a convected flow field

Cited by 11 publications

References 51 publications

Silence is bliss in a Platonic relationship

Silence is bliss in a Platonic relationship

Feasibility analysis for active near/far field acoustic pattern synthesis in free space and shallow water environments

A novel smart hybrid multimorph piezoelectric spherical shell cloak for broadband near-perfect underwater acoustic camouflage applications

Contact Info

Product

Resources

About