Acoustic Finite Element Analysis of Duct Boundaries

Bernhard, Robert J.

doi:10.1121/1.388419

“…Taking into account that the main focus of the proposed FE-Ritz method is to study the propagation of acoustic waves in duct-like domains, it is important to mention the physical characteristics of the internal surfaces. In acoustic studies, it is often desired to describe boundary conditions in terms of acoustic impedance (Bernhard, 1982). Acoustic impedance is defined as the ratio of the acoustic pressure to the normal acoustic velocity at the boundary…”

Section: Acoustic Boundary Conditions and Equations Of Wavesmentioning

confidence: 99%

Development of a Combined-Ritz Method for Modeling 3D Acoustics in Candu Fuel Sub-Channels

Villero¹

2021

Preprint

0

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A combined finite element-Ritz method is developed to effectively model the 3D lowfrequency acoustics in CANDU fuel sub-channels. The complex acoustic behavior of CANDU fuel sub-channels in the cross section is captured using the six-node isoparametric triangular elements; and the acoustic wave propagation in the axial direction is modeled using the polynomials of order n. The Lagrange equations are utilized to formulate the system equations of motion. The acoustic system considered in this study consists of pipe-like medium (water) with rigid and smooth walls. At the inlet of the fuel channel acoustic system, an acoustic pressure wave is prescribed to simulate the pulsation induced by the main feeder pumps. At the outlet, the acoustic system is assumed to interact with a reacting and absorbing material with prescribed acoustic impedance. The method was tested for several scenarios of interest. Numerical results obtained are in excellent agreement with the analytical and ANSYS solutions.

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“…Taking into account that the main focus of the proposed FE-Ritz method is to study the propagation of acoustic waves in duct-like domains, it is important to mention the physical characteristics of the internal surfaces. In acoustic studies, it is often desired to describe boundary conditions in terms of acoustic impedance (Bernhard, 1982). Acoustic impedance is defined as the ratio of the acoustic pressure to the normal acoustic velocity at the boundary…”

Section: Acoustic Boundary Conditions and Equations Of Wavesmentioning

confidence: 99%

Development of a Combined-Ritz Method for Modeling 3D Acoustics in Candu Fuel Sub-Channels

Villero¹

2021

Preprint

0

View full text Add to dashboard Cite

A combined finite element-Ritz method is developed to effectively model the 3D lowfrequency acoustics in CANDU fuel sub-channels. The complex acoustic behavior of CANDU fuel sub-channels in the cross section is captured using the six-node isoparametric triangular elements; and the acoustic wave propagation in the axial direction is modeled using the polynomials of order n. The Lagrange equations are utilized to formulate the system equations of motion. The acoustic system considered in this study consists of pipe-like medium (water) with rigid and smooth walls. At the inlet of the fuel channel acoustic system, an acoustic pressure wave is prescribed to simulate the pulsation induced by the main feeder pumps. At the outlet, the acoustic system is assumed to interact with a reacting and absorbing material with prescribed acoustic impedance. The method was tested for several scenarios of interest. Numerical results obtained are in excellent agreement with the analytical and ANSYS solutions.

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Evaluation of ‘specia’ finite elements with non‐conventional Gaussian quadratures

Bernhard

¹

,

Holger

²

1985

Numerical Meth Engineering

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SUMMARYFinite elements with 'special' basis functions have been proposed to develop better approximations for problems where the behaviour is known to be non-polynomial. This paper discusses extension of Gaussian quadrature integration procedures of non-conventional form to the evaluation of the finite element matrices for 'special' elements. Algorithms for general 'special' elements are discussed. The techniques are applied to 'special' one-and two-dimensional elements for spherically symmetric potential flow. The accuracy of the new 'special' element is shown to be superior to linear and quadratic elements for spherically symmetric potential flow problems.

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Acoustic Finite Element Analysis of Duct Boundaries

Cited by 4 publications

References 16 publications

Development of a Combined-Ritz Method for Modeling 3D Acoustics in Candu Fuel Sub-Channels

Development of a Combined-Ritz Method for Modeling 3D Acoustics in Candu Fuel Sub-Channels

Development of a Combined-Ritz Method for Modeling 3D Acoustics in Candu Fuel Sub-Channels

Evaluation of ‘specia’ finite elements with non‐conventional Gaussian quadratures

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