A nonstandard wave equation, established by Galbrun in 1931, is used to study sound propagation in nonuniform flows. Galbrun's equation describes exactly the same physical phenomenon as the linearized Euler's equations (LEE) but is derived from an Eulerian-Lagrangian description and written only in term of the Lagrangian perturbation of the displacement. This equation has interesting properties and may be a good alternative to the LEE: only acoustic displacement is involved (even in nonhomentropic cases), it provides exact expressions of acoustic intensity and energy, and boundary conditions are easily expressed because acoustic displacement whose normal component is continuous appears explicitly. In this paper, Galbrun's equation is solved using a finite element method in the axisymmetric case. With standard finite elements, the direct displacement-based variational formulation gives some corrupted results. Instead, a mixed finite element satisfying the inf-sup condition is proposed to avoid this problem. A first set of results is compared with semianalytical solutions for a straight duct containing a sheared flow (obtained from Pridmore-Brown's equation). A second set of results concerns a more complex duct geometry with a potential flow and is compared to results obtained from a multiple-scale method (which is an adaptation for the incompressible case of Rienstra's recent work).
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1121/1.1534837 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Bending behavior and influence parameter optimization of connection joints of disc-buckle type formwork support.
Sci Rep
January 2025
China Construction Fifth Engineering Division Corp., Ltd., Changsha, 410004, China.
In order to systematically study the bending behavior of the connection joints of the disc-buckle type formwork support, the accurate numerical model of the disc-buckle type connection joints was obtained through the experimental on the bending behavior of the connection joints of the disc-buckle type, and the bending moment-rotation curve of the joints was verified. The analysis of the failure mode and stress distribution of the joints reveals the importance of the bending behavior of each component. By establishing an accurate numerical model of the joint, the accuracy of the bending experiment of the joint was verified, and the parametric analysis of the influence factors such as the depth of the wedge insertion the disk-plate, the initial position of the wedge insertion the disk-plate, the thickness of the wedge, material constitutive of the wedge and the thickness of the disk-plate was carried out to grasp the influence of the relevant parameters on the bending behavior of the joint.
View Article and Find Full Text PDFRotating radial injection pattern for highly sensitive electrical impedance tomography of human lung anomalies.
Physiol Meas
January 2025
Chair of Measurements and Sensor Technology, Technische Universitat Chemnitz, Reichenhainerstrasse 70, Chemnitz, 09111, GERMANY.
Objective: Electrical Impedance Tomography (EIT) is a non-invasive technique used for lung imaging. A significant challenge in EIT is reconstructing images of deeper thoracic regions due to the low sensitivity of boundary voltages to internal conductivity variations. The current injection pattern is decisive as it influences the current path, boundary voltages, and their sensitivity to tissue changes.
View Article and Find Full Text PDFTowards constructing a generalized structural 3D breathing human lung model based on experimental volumes, pressures, and strains.
PLoS Comput Biol
January 2025
Department of Mechanical Engineering, University of California Riverside, Riverside, California, United States of America.
Respiratory diseases represent a significant healthcare burden, as evidenced by the devastating impact of COVID-19. Biophysical models offer the possibility to anticipate system behavior and provide insights into physiological functions, advancements which are comparatively and notably nascent when it comes to pulmonary mechanics research. In this context, an Inverse Finite Element Analysis (IFEA) pipeline is developed to construct the first continuously ventilated three-dimensional structurally representative pulmonary model informed by both organ- and tissue-level breathing experiments from a cadaveric human lung.
View Article and Find Full Text PDFRadiation efficiency varying equivalent radiated power.
J Acoust Soc Am
January 2025
Grundfos A/S, Bjerringbro, 8550, Denmark.
In this paper, an improved version of the classical equivalent radiated power (ERP) approximation is proposed based on principled physical arguments. A geometry-, frequency-, and vibration pattern-dependent approximation of radiation efficiency is developed and used as a corrective factor for the classical ERP approximation. The proposed method called "radiation efficiency varying equivalent radiated power" (revERP), is shown to greatly improve the accuracy of classical ERP at low Helmholtz numbers, while attaining the accuracy of classical ERP at high Helmholtz numbers.
View Article and Find Full Text PDFFree convection investigation for a Casson-based - nanofluid in semi parabolic enclosure with corrugated cylinder.
Heliyon
January 2025
Biomedical Engineering Department, College of Engineering and Technologies, Al-Mustaqbal University, Hillah, Iraq.
The optimization of heat transfer in various engineering applications, such as thermal management systems and energy storage devices, remains a crucial challenge. This study aims to investigate the potential of Casson-based Cu-HO nanofluids in enhancing free convection heat transfer within complex geometries. The research examines the free convection heat transfer and fluid flow characteristics of a Casson-based Cu-HO nanofluid within a semi-parabolic enclosure that includes a wavy corrugated cylinder.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!