Advanced Computational Dissipative Structural Acoustics and Fluid-Structure Interaction in Low-and Medium-Frequency Domains. Reduced-Order Models and Uncertainty Quantification

R. Ohayon,C. Soize 한국항공우주학회 2012 International Journal of Aeronautical and Space Sc Vol.13 No.2

This paper presents an advanced computational method for the prediction of the responses in the frequency domain of general linear dissipative structural-acoustic and fluid-structure systems, in the low-and medium-frequency do mains and this includes uncertainty quantification. The system under consideration is constituted of a deformable dissipative structure that is coupled with an internal dissipative acoustic fluid. This includes wall acoustic impedances and it is surrounded by an infinite acoustic fluid. The system is submitted to given internal and external acoustic sources and to the prescribed mechanical forces. An efficient reduced-order computational model is constructed by using a finite element discretization for the structure and an internal acoustic fluid. The external acoustic fluid is treated by using an appropriate boundary element method in the frequency domain. All the required modeling aspects for the analysis of the medium-frequency domain have been introduced namely, a viscoelastic behavior for the structure, an appropriate dissipative model for the internal acoustic fluid that includes wall acoustic impedance and a model of uncertainty in particular for the modeling errors. This advanced computational formulation, corresponding to new extensions and complements with respect to the state-of-the-art are well adapted for the development of a new generation of software, in particular for parallel computers.

비적합 유한요소망에 적용가능한 유체-구조물 연결 요소

조정래,이진호,조근희,윤혜진 한국지진공학회 2023 한국지진공학회논문집 Vol.27 No.4

In the fluid-structure interaction analysis, the finite element formulation is performed for the wave equation for dynamic fluid pressure, and the dynamic pressure is defined as a degree of freedom at the fluid nodes. Therefore, to connect the fluid to the structure, it is necessary to connect the degree of freedom of fluid dynamic pressure and the degree of freedom of structure displacement through an interface element derived from the relationship between dynamic pressure and displacement. The previously proposed fluid-structure interface elements use conformal finite element meshes in which the fluid and structure match. However, it is challenging to construct conformal meshes when complex models, such as water purification plants and wastewater treatment facilities, are models. Therefore, to increase modeling convenience, a method is required to model the fluid and structure domains by independent finite element meshes and then connect them. In this study, two fluid-structure interface elements, one based on constraints and the other based on the integration of nonsmooth functions, are proposed in nonconformal finite element meshes for structures and fluids, and their accuracy is verified.

Fluid-structure interaction system predicting both internal pore pressure and outside hydrodynamic pressure

Hadzalic, Emina,Ibrahimbegovic, Adnan,Dolarevic, Samir Techno-Press 2018 Coupled systems mechanics Vol.7 No.6

In this paper, we present a numerical model for fluid-structure interaction between structure built of porous media and acoustic fluid, which provides both pore pressure inside porous media and hydrodynamic pressures and hydrodynamic forces exerted on the upstream face of the structure in an unified manner and simplifies fluid-structure interaction problems. The first original feature of the proposed model concerns the structure built of saturated porous medium whose response is obtained with coupled discrete beam lattice model, which is based on Voronoi cell representation with cohesive links as linear elastic Timoshenko beam finite elements. The motion of the pore fluid is governed by Darcy's law, and the coupling between the solid phase and the pore fluid is introduced in the model through Biot's porous media theory. The pore pressure field is discretized with CST (Constant Strain Triangle) finite elements, which coincide with Delaunay triangles. By exploiting Hammer quadrature rule for numerical integration on CST elements, and duality property between Voronoi diagram and Delaunay triangulation, the numerical implementation of the coupling results with an additional pore pressure degree of freedom placed at each node of a Timoshenko beam finite element. The second original point of the model concerns the motion of the outside fluid which is modeled with mixed displacement/pressure based formulation. The chosen finite element representations of the structure response and the outside fluid motion ensures for the structure and fluid finite elements to be connected directly at the common nodes at the fluid-structure interface, because they share both the displacement and the pressure degrees of freedom. Numerical simulations presented in this paper show an excellent agreement between the numerically obtained results and the analytical solutions.

Advanced Computational Dissipative Structural Acoustics and Fluid-Structure Interaction in Low-and Medium-Frequency Domains. Reduced-Order Models and Uncertainty Quantification

Ohayon, R.,Soize, C. The Korean Society for Aeronautical and Space Scie 2012 International Journal of Aeronautical and Space Sc Vol.13 No.2

This paper presents an advanced computational method for the prediction of the responses in the frequency domain of general linear dissipative structural-acoustic and fluid-structure systems, in the low-and medium-frequency domains and this includes uncertainty quantification. The system under consideration is constituted of a deformable dissipative structure that is coupled with an internal dissipative acoustic fluid. This includes wall acoustic impedances and it is surrounded by an infinite acoustic fluid. The system is submitted to given internal and external acoustic sources and to the prescribed mechanical forces. An efficient reduced-order computational model is constructed by using a finite element discretization for the structure and an internal acoustic fluid. The external acoustic fluid is treated by using an appropriate boundary element method in the frequency domain. All the required modeling aspects for the analysis of the medium-frequency domain have been introduced namely, a viscoelastic behavior for the structure, an appropriate dissipative model for the internal acoustic fluid that includes wall acoustic impedance and a model of uncertainty in particular for the modeling errors. This advanced computational formulation, corresponding to new extensions and complements with respect to the state-of-the-art are well adapted for the development of a new generation of software, in particular for parallel computers.

Comparing of Loose and Strong Finite Element Partitioned Coupling Methods of Acoustic Fluid-Structure Interaction: Concrete Dam-Reservoir System

Farhoud Kalateh,Ali Koosheh 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.3

The objective of this paper deals with some new features of partitioned solution techniques of three-dimensional acoustic fluidstructure dynamic interaction including, concrete dam- reservoir systems. The equation of motion of the fluid, considered inviscid and compressible, is expressed in terms of the pressure variable alone. Structure equation of motion is discretized using standard displacement-base finite element method and assumed structure behaves linearly throughout analysis. Explicit staggered and iterative partition schemes are two different partitioned solution methods that are developed to time integration of fluid and structure dynamic equations. Solution procedures are explained in detail followed by various examples. Their computational costs as well as their computational efficiency are compared. Finally, the article gives some hints about the performance of proposed coupled partitioned solution schemes.

Finite Element Vibration Analysis of Cylindrical Shells Conveying Fluid with Considering Acoustic-Structure Interactions

JEONG, Weui Bong,SEO, Young Soo,AHN, Se Jin,YOO, Wan Suk Japan Society of Mechanical Engineers 2006 JSME international journal Mechanical systems, mac Vol.49 No.2

<P>The dynamic behavior of the cylindrical shell with uniform flow is formulated by the finite element method. The dynamics of the shell is based on Donnell’s theory and the fluid in cylindrical shell is considered satisfying the Helmholtz equation. The effective thickness of fluid is calculated according to the circumferential modes and the frequencies. An estimation of the FRF (frequency response function) of the shell with taking into consideration of the coupled effects of the internal fluid is presented. These results are compared with the results considering fluid satisfying Laplace equation. The influence of fluid velocity on the FRF is also discussed.</P>

이중저 형상 구조물의 음향방사효율과 수중방사소음 해석

최성원,김국현,조대승,서규열 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.11

In general, fluid-structure interaction analysis techniques are applied to accurately predict underwater radiated noise (URN) from a ship structure, particularly in low frequency range (below 500Hz). In this paper, URN from a double bottom-shaped structure of a ship has been numerically investigated based on a traditional fluid-structure interaction analysis techniques. For this purpose, a coupling method of finite element and boundary element method (FE/BEM) has been presented. A numerical model has generated referring to a double bottom structure arrangement of a general ship. Acoustic radiation efficiency and URN transfer function, by harmonically and vertically excited forces on the top plate of the double bottom, have been evaluated. The results are compared with those of an empirical formula and a simple equation which are usually adopted for URN assessment in design stage, respectively. It has been concluded that the empirical formula of acoustics radiation efficiency needs to be modified in low frequency range for more precise estimation of ship URN in low frequency ranges.

Hydro-elastic analysis of marine propellers based on a BEM-FEM coupled FSI algorithm

Lee, Hyoungsuk,Song, Min-Churl,Suh, Jung-Chun,Chang, Bong-Jun The Society of Naval Architects of Korea 2014 International Journal of Naval Architecture and Oc Vol.6 No.3

A reliable steady/transient hydro-elastic analysis is developed for flexible (composite) marine propeller blade design which deforms according to its environmental load (ship speed, revolution speed, wake distribution, etc.) Hydro-elastic analysis based on CFD and FEM has been widely used in the engineering field because of its accurate results however it takes large computation time to apply early propeller design stage. Therefore the analysis based on a boundary element method-Finite Element Method (BEM-FEM) Fluid-Structure Interaction (FSI) is introduced for computational efficiency and accuracy. The steady FSI analysis, and its application to reverse engineering, is designed for use regarding optimum geometry and ply stack design. A time domain two-way coupled transient FSI analysis is developed by considering the hydrodynamic damping ffects of added mass due to fluid around the propeller blade. The analysis makes possible to evaluate blade strength and also enable to do risk assessment by estimating the change in performance and the deformation depending on blade position in the ship's wake. To validate this hydro-elastic analysis methodology, published model test results of P5479 and P5475 are applied to verify the steady and the transient FSI analysis, respectively. As the results, the proposed steady and unsteady analysis methodology gives sufficient accuracy to apply flexible marine propeller design.

Hydro-elastic analysis of marine propellers based on a BEM-FEM coupled FSI algorithm

이형석,송민철,서정천,장봉준 대한조선학회 2014 International Journal of Naval Architecture and Oc Vol.6 No.3

A reliable steady/transient hydro-elastic analysis is developed for flexible (composite) marine propeller blade design which deforms according to its environmental load (ship speed, revolution speed, wake distribution, etc.) Hydro-elastic analysis based on CFD and FEM has been widely used in the engineering field because of its accurate results however it takes large computation time to apply early propeller design stage. Therefore the analysis based on a boundary element method-Finite Element Method (BEM-FEM) Fluid-Structure Interaction (FSI) is introduced for com-putational efficiency and accuracy. The steady FSI analysis, and its application to reverse engineering, is designed for use regarding optimum geometry and ply stack design. A time domain two-way coupled transient FSI analysis is dev-eloped by considering the hydrodynamic damping ffects of added mass due to fluid around the propeller blade. The analysis makes possible to evaluate blade strength and also enable to do risk assessment by estimating the change in performance and the deformation depending on blade position in the ship’s wake. To validate this hydro-elastic analysis methodology, published model test results of P5479 and P5475 are applied to verify the steady and the transient FSI analysis, respectively. As the results, the proposed steady and unsteady analysis methodology gives sufficient accuracy to apply flexible marine propeller design.

매설형 하이드로폰 시스템의 구조-음향 연성 해석

서희선(Seo, Hee-Seon),조요한(Cho, Yo-Han),조치영(Joh, Chee-Young) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.9

A study was carried out to investigate the fluid-structure interaction phenomena of buried hydrophone system that exposed complex loads due to handling, transportation and installation. The buried hydrophone system has necessarily neighborhood structures for installation. Because of the neighborhood structure, acoustic field is deformed. We analyze the piezoelectric-structural-acoustic coupled problem and the results to use a finite element analysis software, ANSYS, which has an coupled field analysis capability. The effect of the component of hydrophone system is revealed altogether in pressure distribution. So, we classify and analyze the problem by four different compositions for decomposition.