Analysis of three‐dimensional acoustic scattering from doubly periodic structures using a source model

1992 ◽  
Vol 91 (2) ◽  
pp. 572-580 ◽  
Author(s):  
Amir Boag ◽  
Yehuda Leviatan ◽  
Alona Boag
Keyword(s):  
Periodic Structures ◽  
Three Dimensional ◽  
Acoustic Scattering ◽  
Source Model ◽  
Doubly Periodic Structures

An acoustic liner design methodology based on a statistical source model

2021 ◽  
pp. 1475472X2110238
Author(s):  
Douglas M Nark ◽  
Michael G Jones
Keyword(s):  
Design Methodology ◽  
Three Dimensional ◽  
Aircraft Engine ◽  
Flight Test ◽  
Source Model ◽  
Practical Implementation ◽  
Source Information ◽  
Fan Noise ◽  
Future Design ◽  
Acoustic Liner

The attenuation of fan tones remains an important aspect of fan noise reduction for high bypass ratio turbofan engines. However, as fan design considerations have evolved, the simultaneous reduction of broadband fan noise levels has gained interest. Advanced manufacturing techniques have also opened new possibilities for the practical implementation of broadband liner concepts. To effectively address these elements, practical acoustic liner design methodologies must provide the capability to efficiently predict the acoustic benefits of novel liner configurations. This paper describes such a methodology to design and evaluate multiple candidate liner configurations using realistic, three dimensional geometries for which minimal source information is available. The development of the design methodology has been guided by a series of studies culminating in the design and flight test of a low drag, broadband inlet liner. The excellent component and system noise benefits obtained in this test demonstrate the effectiveness of the broadband liner design process. They also illustrate the value of the approach in concurrently evaluating multiple liner designs and their application to various locations within the aircraft engine nacelle. Thus, the design methodology may be utilized with increased confidence to investigate novel liner configurations in future design studies.

scholarly journals Imaging of bi-anisotropic periodic structures from electromagnetic near-field data

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Dinh-Liem Nguyen ◽  
Trung Truong
Keyword(s):  
Inverse Scattering ◽  
Maxwell Equations ◽  
Field Data ◽  
Periodic Structures ◽  
Near Field ◽  
Scattering Problem ◽  
Three Dimensional ◽  
Inverse Scattering Problem ◽  
Factorization Method ◽  
Unique Determination

AbstractThis paper is concerned with the inverse scattering problem for the three-dimensional Maxwell equations in bi-anisotropic periodic structures. The inverse scattering problem aims to determine the shape of bi-anisotropic periodic scatterers from electromagnetic near-field data at a fixed frequency. The factorization method is studied as an analytical and numerical tool for solving the inverse problem. We provide a rigorous justification of the factorization method which results in the unique determination and a fast imaging algorithm for the periodic scatterer. Numerical examples for imaging three-dimensional periodic structures are presented to examine the efficiency of the method.

FEA of SAW penetration of Ramor 500 steel

2020 ◽  
Vol 62 (12) ◽  
pp. 1192-1198
Author(s):  
Ali Kaya Gur ◽  
Semih Taskaya ◽  
Subramaniam Shankar ◽  
Thangamuthu Mohanraj
Keyword(s):  
Three Dimensional ◽  
Welding Process ◽  
Source Model ◽  
Strength Properties ◽  
Steel Plates ◽  
Constant Current ◽  
Welding Seam ◽  
Depth Increase ◽  
Thermal Cooling ◽  
Submerged Arc

Abstract Ramor 500 steel plates are used as a ballistic material due to their greater hardness and strength properties. This steel can be produced with a 2-30 mm thickness sheet which may attain 505-590 HV hardness. In the present work, Ramor 500 steel pairs are joined using a submerged arc welding (SAW) process and taking various parameters into consideration. An austenitic additional wire is used for the welding process which contains Cr, Ni, and Mn. The source model prototype was developed using ANSYS software and considering a time-dependent three dimensional thermal model with source cooling. The highest tensile stress voltage value was determined in the sample applying a constant current of 250 A, 25 V and 30 cm × min-1welding speed. It was observed that the welding seam width increases as welding tension grows and that welding height and depth increase and decrease more or less in tandem. A ANSYS thermal cooling analysis revealed that welding tension grows with heat transfer which increases 15 mm from the main center of the welding area.

Adaptivity and Three Dimensional Hierarchical Boundary Elements for Rigid Acoustic Scattering Problems

1995 ◽  
Author(s):  
Steven J. Newhouse ◽  
Ian C. Mathews
Keyword(s):  
Boundary Element ◽  
Acoustic Analysis ◽  
Three Dimensional ◽  
Acoustic Scattering ◽  
Error Estimator ◽  
Infinite Domain ◽  
Scattering Problems ◽  
Effective Form ◽  
Mesh Density ◽  
Acoustic Scattering Problems

Abstract The boundary element method is an established numerical tool for the analysis of acoustic pressure fields in an infinite domain. There is currently no well established method of estimating the surface pressure error distribution for an arbitrary three dimensional body. Hierarchical shape functions have been used as a highly effective form of p refinement in many finite and boundary element applications. Their ability to be used as an error estimator in acoustic analysis has never been fully exploited. This paper studies the influence of mesh density and interpolation order on several acoustic scattering problems. A hierarchical error estimator is implemented and its effectiveness verified against the spherical problem. A coarse cylindrical mesh is then refined using the new error estimator until the solution has converged. The effectiveness of this analysis is shown by comparing the error indicators derived during the analysis to the solution generated from a very fine cylindrical mesh.

scholarly journals A 3D In Vitro Model for Burn Wounds: Monitoring of Regeneration on the Epidermal Level

Biomedicines ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1153
Author(s):  
Verena Schneider ◽  
Daniel Kruse ◽  
Ives Bernardelli de Mattos ◽  
Saskia Zöphel ◽  
Kendra-Kathrin Tiltmann ◽  
...  
Keyword(s):  
Wound Healing ◽  
Inflammatory Response ◽  
Healing Process ◽  
Three Dimensional ◽  
Source Model ◽  
Burn Wound ◽  
Thermal Burn ◽  
Burn Wounds

Burns affect millions every year and a model to mimic the pathophysiology of such injuries in detail is required to better understand regeneration. The current gold standard for studying burn wounds are animal models, which are under criticism due to ethical considerations and a limited predictiveness. Here, we present a three-dimensional burn model, based on an open-source model, to monitor wound healing on the epidermal level. Skin equivalents were burned, using a preheated metal cylinder. The healing process was monitored regarding histomorphology, metabolic changes, inflammatory response and reepithelialization for 14 days. During this time, the wound size decreased from 25% to 5% of the model area and the inflammatory response (IL-1β, IL-6 and IL-8) showed a comparable course to wounding and healing in vivo. Additionally, the topical application of 5% dexpanthenol enhanced tissue morphology and the number of proliferative keratinocytes in the newly formed epidermis, but did not influence the overall reepithelialization rate. In summary, the model showed a comparable healing process to in vivo, and thus, offers the opportunity to better understand the physiology of thermal burn wound healing on the keratinocyte level.

scholarly journals A General Expression for the Stagnant Thermal Conductivity of Stochastic and Periodic Structures

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
X. Bai ◽  
C. Hasan ◽  
M. Mobedi ◽  
A. Nakayama
Keyword(s):  
Thermal Conductivity ◽  
General Expression ◽  
Metal Foam ◽  
Solid Angle ◽  
Periodic Structures ◽  
Three Dimensional ◽  
High Thermal Conductivity ◽  
Numerical Calculations ◽  
The One ◽  
Good Agreement

A general expression has been obtained to estimate thermal conductivities of both stochastic and periodic structures with high-solid thermal conductivity. An air layer partially occupied by slanted circular rods of high-thermal conductivity was considered to derive the general expression. The thermal conductivity based on this general expression was compared against that obtained from detailed three-dimensional numerical calculations. A good agreement between two sets of results substantiates the validity of the general expression for evaluating the stagnant thermal conductivity of the periodic structures. Subsequently, this expression was averaged over a hemispherical solid angle to estimate the stagnant thermal conductivity for stochastic structures such as a metal foam. The resulting expression was found identical to the one obtained by Hsu et al., Krishnan et al., and Yang and Nakayama. Thus, the general expression can be used for both stochastic and periodic structures.

Sign in / Sign up

Export Citation Format

Share Document